STS066-157-192 The Bosporus, Turkey November 1994

The Bosporus (near the center of the photograph), a strait that connects the Black Sea to the north with the Sea of Marmara to the south, stands out in this low-oblique, north-looking photograph. One of the world’s most strategic waterways, the strait separates European Turkey to the west with Asiatic Turkey to the east. Structurally the Bosporus is an inundated valley that follows an irregular northeast-southwest course 19 miles (30 kilometers) long, with widths varying from approximately 2 miles (4 kilometers) at its northern mouth to 800 yards (730 meters) at Rumelihasari, midway of the strait. The current flows north to south; however, a strong subsurface countercurrent with numerous points and coves sets up swirls and eddies that make navigation dangerous to the inexperienced. Istanbul (formerly Constantinople), one of the great historic cities of the world, sits near the Bosporus entrance to the Sea of Marmara. A city of more than 3 million people, Istanbul is Turkey’s major seaport as well as its commercial, financial, and cultural center. The city, like Rome, is built on seven hills. Major industries include shipbuilding, tobacco, textiles, glass products, leather goods (especially shoes), cement, and tourism. The European (western) side of Istanbul is the terminus of an international rail service formerly called the Orient Express. The Bosporus Bridge, connecting the European and Asian sections of the city, was opened in 1973 and is one of the longest suspension bridges in the world [3524 feet (1074 meters)].

Leatherback Sea Turtle (Dermochelys coriacea) at the National Museum of Natural History in Washington, DC on April-9th-2022.

It

is the largest of all living turtles and the heaviest non-crocodilian reptile, reaching lengths of up to 2 metres and weights of 600 kg.t is the only living species in the genus Dermochelys and family Dermochelyidae. It can easily be differentiated from other modern sea turtles by its lack of a bony shell; instead, its carapace is covered by oily flesh and flexible, leather-like skin, for which it is named.

 

Leatherback turtles have the most hydrodynamic body of any sea turtle, with a large, teardrop-shaped body. A large pair of front flippers powers the turtles through the water. Like other sea turtles, the leatherback has flattened forelimbs adapted for swimming in the open ocean. Claws are absent from both pairs of flippers. The leatherback's flippers are the largest in proportion to its body among extant sea turtles. Leatherback's front flippers can grow up to 2.7 m (8.9 ft) in large specimens, the largest flippers (even in comparison to its body) of any sea turtle.

 

The leatherback has several characteristics that distinguish it from other sea turtles. Its most notable feature is the lack of a bony carapace. Instead of scutes, it has thick, leathery skin with embedded minuscule osteoderms. Seven distinct ridges rise from the carapace, crossing from the cranial to caudal margin of the turtle's back. Leatherbacks are unique among reptiles in that their scales lack β-keratin. The entire turtle's dorsal surface is colored dark grey to black, with a scattering of white blotches and spots. Demonstrating countershading, the turtle's underside is lightly colored.[21] Instead of teeth, the leatherback turtle has points on the tomium of its upper lip, with backwards spines in its throat (esophagus) to help it swallow food and to stop its prey from escaping once caught.

  

Esophagus of a leatherback sea turtle showing spines to retain prey

D. coriacea adults average 1–1.75 m (3.3–5.7 ft) in curved carapace length (CCL), 1.83–2.2 m (6.0–7.2 ft) in total length, and 250 to 700 kg (550 to 1,540 lb) in weight.In the Caribbean, the mean size of adults was reported at 384 kg (847 lb) in weight and 1.55 m (5.1 ft) in CCL. Similarly, those nesting in French Guiana, weighed an average of 339.3 kg (748 lb) and measured 1.54 m (5.1 ft) in CCL.[24][25] The largest verified specimen ever found was discovered on the Pakistani beach of Sandspit and measured 213 cm (6.99 ft) in CCL and 650 kg (1,433 lb) in weight. A previous contender, the "Harlech turtle", was purportedly 256.5 cm (8.42 ft) in CCL and 916 kg (2,019 lb) in weight,however recent inspection of its remains housed at the National Museum Cardiff have found that its true CCL is closer to 1.5 m (4.9 ft), casting doubt on the accuracy of the claimed weight, as well. On the other hand, one scientific paper has claimed that the species can weigh up to 1,000 kg (2,200 lb) without providing more verifiable detail.The leatherback turtle is scarcely larger than any other sea turtle upon hatching, as they average 61.3 mm (2.41 in) in carapace length and weigh around 46 g (1.6 oz) when freshly hatched.

 

D. coriacea exhibits several anatomical characteristics believed to be associated with a life in cold waters, including an extensive covering of brown adipose tissue, temperature-independent swimming muscles,countercurrent heat exchangers between the large front flippers and the core body, and an extensive network of countercurrent heat exchangers surrounding the trachea.

  

Leatherbacks have been viewed as unique among extant reptiles for their ability to maintain high body temperatures using metabolically generated heat, or endothermy. Initial studies on their metabolic rates found leatherbacks had resting metabolisms around three times higher than expected for reptiles of their size. However, recent studies using reptile representatives encompassing all the size ranges leatherbacks pass through during ontogeny discovered the resting metabolic rate of a large D. coriacea is not significantly different from predicted results based on allometry.

 

Rather than using a high resting metabolism, leatherbacks appear to take advantage of a high activity rate. Studies on wild D. coriacea discovered individuals may spend as little as 0.1% of the day resting.This constant swimming creates muscle-derived heat. Coupled with their countercurrent heat exchangers, insulating fat covering, and large size, leatherbacks are able to maintain high temperature differentials compared to the surrounding water. Adult leatherbacks have been found with core body temperatures that were 18 °C (32 °F) above the water in which they were swimming.

 

Leatherback turtles are one of the deepest-diving marine animals. Individuals have been recorded diving to depths as great as 1,280 m (4,200 ft).[37][38] Typical dive durations are between 3 and 8 minutes, with dives of 30–70 minutes occurring infrequently.

 

They are also the fastest-moving non-avian reptiles. The 1992 edition of the Guinness Book of World Records lists the leatherback turtle moving at 35.28 km/h (21.92 mph) in the water. More typically, they swim at 1.80–10.08 km/h (1.12–6.26 mph

 

Leatherback sea turtles can be found primarily in the open ocean. Scientists tracked a leatherback turtle that swam from Jen Womom beach of Tambrauw Regency in West Papua of Indonesia to the U.S. in a 20,000 km (12,000 mi) foraging journey over a period of 647 days.[20][54] Leatherbacks follow their jellyfish prey throughout the day, resulting in turtles "preferring" deeper water in the daytime, and shallower water at night (when the jellyfish rise up the water column).[35] This hunting strategy often places turtles in very frigid waters. One individual was found actively hunting in waters where temperatures were as low as 0.4 °C (32.7 °F). Following each foraging dive, the leatherback would return to warmer (17.5 °C (63.5 °F)) surface waters to regain body heat before continuing to dive into near freezing waters.[55] Leatherback turtles are known to pursue prey deeper than 1000 m—beyond the physiological limits of all other diving tetrapods except for beaked whales and sperm whales.[56]

 

Their favored breeding beaches are mainland sites facing the deep water, and they seem to avoid those sites protected by coral reefs.[57]

 

Adult D. coriacea turtles subsist almost entirely on jellyfish.Due to their obligate feeding nature, leatherbacks help control jellyfish populations.[5] Leatherbacks also feed on other soft-bodied organisms, such as tunicates and cephalopods.

 

Pacific leatherbacks migrate about 6,000 mi (9,700 km) across the Pacific from their nesting sites in Indonesia to eat California jellyfish. One cause for their endangered state is plastic bags floating in the ocean. Pacific leatherback sea turtles mistake these plastic bags for jellyfish; an estimated one-third of adults have ingested plastic. Plastic enters the oceans along the west coast of urban areas, where leatherbacks forage, with Californians using upward of 19 billion plastic bags every year.

 

Several species of sea turtles commonly ingest plastic marine debris, and even small quantities of debris can kill sea turtles by obstructing their digestive tracts.Nutrient dilution, which occurs when plastics displace food in the gut, affects the nutrient gain and consequently the growth of sea turtles.[ Ingestion of marine debris and slowed nutrient gain leads to increased time for sexual maturation that may affect future reproductive behaviors.[63] These turtles have the highest risk of encountering and ingesting plastic bags offshore of San Francisco Bay, the Columbia River mouth, and Puget Sound.

  

The leatherback turtle is a species with a cosmopolitan global range. Of all the extant sea turtle species, D. coriacea has the widest distribution, reaching as far north as Alaska and Norway and as far south as Cape Agulhas in Africa and the southernmost tip of New Zealand.[20] The leatherback is found in all tropical and subtropical oceans, and its range extends well into the Arctic Circle.

 

The three major, genetically distinct populations occur in the Atlantic, eastern Pacific, and western Pacific Oceans.[ While nesting beaches have been identified in the region, leatherback populations in the Indian Ocean remain generally unassessed and unevaluated.

 

Recent estimates of global nesting populations are that 26,000 to 43,000 females nest annually, which is a dramatic decline from the 115,000 estimated in 1980.

 

Atlantic subpopulation

The leatherback turtle population in the Atlantic Ocean ranges across the entire region. They range as far north as the North Sea and to the Cape of Good Hope in the south. Unlike other sea turtles, leatherback feeding areas are in colder waters, where an abundance of their jellyfish prey is found, which broadens their range. However, only a few beaches on both sides of the Atlantic provide nesting sites.

 

Off the Atlantic coast of Canada, leatherback turtles feed in the Gulf of Saint Lawrence near Quebec and as far north as Newfoundland and Labrador.[47] The most significant Atlantic nesting sites are in Suriname, Guyana, French Guiana in South America, Antigua and Barbuda, and Trinidad and Tobago in the Caribbean, and Gabon in Central Africa. The beaches of Mayumba National Park in Mayumba, Gabon, host the largest nesting population on the African continent and possibly worldwide, with nearly 30,000 turtles visiting its beaches each year between October and April. Off the northeastern coast of the South American continent, a few select beaches between French Guiana and Suriname are primary nesting sites of several species of sea turtles, the majority being leatherbacks. A few hundred nest annually on the eastern coast of Florida.[6] In Costa Rica, the beaches of Gandoca and Parismina provide nesting grounds.

 

Pacific subpopulation

Pacific leatherbacks divide into two populations. One population nests on beaches in Papua, Indonesia, and the Solomon Islands, and forages across the Pacific in the Northern Hemisphere, along the coasts of California, Oregon, and Washington in North America. The eastern Pacific population forages in the Southern Hemisphere, in waters along the western coast of South America, nesting in Mexico, Panama, El Salvador, Nicaragua, and Costa Rica,as well as eastern Australia.

 

The continental United States offers two major Pacific leatherback feeding areas. One well-studied area is just off the northwestern coast near the mouth of the Columbia River. The other American area is located in California.[50] Further north, off the Pacific coast of Canada, leatherbacks visit the beaches of British Columbia.

 

Estimates by the WWF suggest only 2,300 adult females of the Pacific leatherback remain, making it the most endangered marine turtle subpopulation.

 

South China Sea subpopulation

A third possible Pacific subpopulation has been proposed, those that nest in Malaysia. This subpopulation, however, has effectively been eradicated. The beach of Rantau Abang in Terengganu, Malaysia, once had the largest nesting population in the world, hosting 10,000 nests per year. The major cause of the decline was egg consumption by humans. Conservation efforts initiated in the 1960s were ineffective because they involved excavating and incubating eggs at artificial sites which inadvertently exposed the eggs to high temperatures. It only became known in the 1980s that sea turtles undergo temperature-dependent sex determination; it is suspected that nearly all the artificially incubated hatchlings were female.[53] In 2008, two turtles nested at Rantau Abang, and unfortunately, the eggs were infertile. Additionally, there are small nesting sites in southern Thailand where 18 turtles nested in 2021

 

Indian Ocean subpopulation

While little research has been done on Dermochelys populations in the Indian Ocean, nesting populations are known from Sri Lanka and the Nicobar Islands. These turtles are proposed to form a separate, genetically distinct Indian Ocean subpopulation.[

  

Lifespan

Very little is known of the species' lifespan. Some reports claim "30 years or more", while others state "50 years or more".Upper estimates exceed 100 years.

 

Death and decomposition

Dead leatherbacks that wash ashore are microecosystems while decomposing. In 1996, a drowned carcass held sarcophagid and calliphorid flies after being picked open by a pair of Coragyps atratus vultures. Infestation by carrion-eating beetles of the families Scarabaeidae, Carabidae, and Tenebrionidae soon followed. After days of decomposition, beetles from the families Histeridae and Staphylinidae and anthomyiid flies invaded the corpse, as well. Organisms from more than a dozen families took part in consuming the carcass.

  

Leatherback turtles face many predators in their early lives. Eggs may be preyed on by a diversity of coastal predators, including ghost crabs, monitor lizards, raccoons, coatis, dogs, coyotes, genets, mongooses, and shorebirds ranging from small plovers to large gulls. Many of the same predators feed on baby turtles as they try to get to the ocean, as well as frigatebirds and varied raptors. Once in the ocean, young leatherbacks still face predation from cephalopods, requiem sharks, and various large fish. Despite their lack of a hard shell, the huge adults face fewer serious predators, though they are occasionally overwhelmed and preyed on by very large marine predators such as killer whales, great white sharks, and tiger sharks. Nesting females have been preyed upon by jaguars in the American tropics.

 

The adult leatherback has been observed aggressively defending itself at sea from predators. A medium-sized adult was observed chasing a shark that had attempted to bite it and then turned its aggression and attacked the boat containing the humans observing the prior interaction.Dermochelys juveniles spend more of their time in tropical waters than do adults.

 

Adults are prone to long-distance migration. Migration occurs between the cold waters where mature leatherbacks feed, to the tropical and subtropical beaches in the regions where they hatch. In the Atlantic, females tagged in French Guiana have been recaptured on the other side of the ocean in Morocco and Spain.

  

Mating takes place at sea. Males never leave the water once they enter it, unlike females, which nest on land. After encountering a female (which possibly exudes a pheromone to signal her reproductive status), the male uses head movements, nuzzling, biting, or flipper movements to determine her receptiveness. Males can mate every year but the females mate every two to three years. Fertilization is internal, and multiple males usually mate with a single female. This polyandry does not provide the offspring with any special advantages. Female leatherbacks are known to nest up to 10 times in a single nesting season giving them the shortest internesting interval of all sea turtles.

   

Leatherback Sea Turtle (Dermochelys coriacea) at the National Museum of Natural History in Washington, DC on April-9th-2022.

It

is the largest of all living turtles and the heaviest non-crocodilian reptile, reaching lengths of up to 2 metres and weights of 600 kg.t is the only living species in the genus Dermochelys and family Dermochelyidae. It can easily be differentiated from other modern sea turtles by its lack of a bony shell; instead, its carapace is covered by oily flesh and flexible, leather-like skin, for which it is named.

 

Leatherback turtles have the most hydrodynamic body of any sea turtle, with a large, teardrop-shaped body. A large pair of front flippers powers the turtles through the water. Like other sea turtles, the leatherback has flattened forelimbs adapted for swimming in the open ocean. Claws are absent from both pairs of flippers. The leatherback's flippers are the largest in proportion to its body among extant sea turtles. Leatherback's front flippers can grow up to 2.7 m (8.9 ft) in large specimens, the largest flippers (even in comparison to its body) of any sea turtle.

 

The leatherback has several characteristics that distinguish it from other sea turtles. Its most notable feature is the lack of a bony carapace. Instead of scutes, it has thick, leathery skin with embedded minuscule osteoderms. Seven distinct ridges rise from the carapace, crossing from the cranial to caudal margin of the turtle's back. Leatherbacks are unique among reptiles in that their scales lack β-keratin. The entire turtle's dorsal surface is colored dark grey to black, with a scattering of white blotches and spots. Demonstrating countershading, the turtle's underside is lightly colored.[21] Instead of teeth, the leatherback turtle has points on the tomium of its upper lip, with backwards spines in its throat (esophagus) to help it swallow food and to stop its prey from escaping once caught.

  

Esophagus of a leatherback sea turtle showing spines to retain prey

D. coriacea adults average 1–1.75 m (3.3–5.7 ft) in curved carapace length (CCL), 1.83–2.2 m (6.0–7.2 ft) in total length, and 250 to 700 kg (550 to 1,540 lb) in weight.In the Caribbean, the mean size of adults was reported at 384 kg (847 lb) in weight and 1.55 m (5.1 ft) in CCL. Similarly, those nesting in French Guiana, weighed an average of 339.3 kg (748 lb) and measured 1.54 m (5.1 ft) in CCL.[24][25] The largest verified specimen ever found was discovered on the Pakistani beach of Sandspit and measured 213 cm (6.99 ft) in CCL and 650 kg (1,433 lb) in weight. A previous contender, the "Harlech turtle", was purportedly 256.5 cm (8.42 ft) in CCL and 916 kg (2,019 lb) in weight,however recent inspection of its remains housed at the National Museum Cardiff have found that its true CCL is closer to 1.5 m (4.9 ft), casting doubt on the accuracy of the claimed weight, as well. On the other hand, one scientific paper has claimed that the species can weigh up to 1,000 kg (2,200 lb) without providing more verifiable detail.The leatherback turtle is scarcely larger than any other sea turtle upon hatching, as they average 61.3 mm (2.41 in) in carapace length and weigh around 46 g (1.6 oz) when freshly hatched.

 

D. coriacea exhibits several anatomical characteristics believed to be associated with a life in cold waters, including an extensive covering of brown adipose tissue, temperature-independent swimming muscles,countercurrent heat exchangers between the large front flippers and the core body, and an extensive network of countercurrent heat exchangers surrounding the trachea.

  

Leatherbacks have been viewed as unique among extant reptiles for their ability to maintain high body temperatures using metabolically generated heat, or endothermy. Initial studies on their metabolic rates found leatherbacks had resting metabolisms around three times higher than expected for reptiles of their size. However, recent studies using reptile representatives encompassing all the size ranges leatherbacks pass through during ontogeny discovered the resting metabolic rate of a large D. coriacea is not significantly different from predicted results based on allometry.

 

Rather than using a high resting metabolism, leatherbacks appear to take advantage of a high activity rate. Studies on wild D. coriacea discovered individuals may spend as little as 0.1% of the day resting.This constant swimming creates muscle-derived heat. Coupled with their countercurrent heat exchangers, insulating fat covering, and large size, leatherbacks are able to maintain high temperature differentials compared to the surrounding water. Adult leatherbacks have been found with core body temperatures that were 18 °C (32 °F) above the water in which they were swimming.

 

Leatherback turtles are one of the deepest-diving marine animals. Individuals have been recorded diving to depths as great as 1,280 m (4,200 ft).[37][38] Typical dive durations are between 3 and 8 minutes, with dives of 30–70 minutes occurring infrequently.

 

They are also the fastest-moving non-avian reptiles. The 1992 edition of the Guinness Book of World Records lists the leatherback turtle moving at 35.28 km/h (21.92 mph) in the water. More typically, they swim at 1.80–10.08 km/h (1.12–6.26 mph

 

Leatherback sea turtles can be found primarily in the open ocean. Scientists tracked a leatherback turtle that swam from Jen Womom beach of Tambrauw Regency in West Papua of Indonesia to the U.S. in a 20,000 km (12,000 mi) foraging journey over a period of 647 days.[20][54] Leatherbacks follow their jellyfish prey throughout the day, resulting in turtles "preferring" deeper water in the daytime, and shallower water at night (when the jellyfish rise up the water column).[35] This hunting strategy often places turtles in very frigid waters. One individual was found actively hunting in waters where temperatures were as low as 0.4 °C (32.7 °F). Following each foraging dive, the leatherback would return to warmer (17.5 °C (63.5 °F)) surface waters to regain body heat before continuing to dive into near freezing waters.[55] Leatherback turtles are known to pursue prey deeper than 1000 m—beyond the physiological limits of all other diving tetrapods except for beaked whales and sperm whales.[56]

 

Their favored breeding beaches are mainland sites facing the deep water, and they seem to avoid those sites protected by coral reefs.[57]

 

Adult D. coriacea turtles subsist almost entirely on jellyfish.Due to their obligate feeding nature, leatherbacks help control jellyfish populations.[5] Leatherbacks also feed on other soft-bodied organisms, such as tunicates and cephalopods.

 

Pacific leatherbacks migrate about 6,000 mi (9,700 km) across the Pacific from their nesting sites in Indonesia to eat California jellyfish. One cause for their endangered state is plastic bags floating in the ocean. Pacific leatherback sea turtles mistake these plastic bags for jellyfish; an estimated one-third of adults have ingested plastic. Plastic enters the oceans along the west coast of urban areas, where leatherbacks forage, with Californians using upward of 19 billion plastic bags every year.

 

Several species of sea turtles commonly ingest plastic marine debris, and even small quantities of debris can kill sea turtles by obstructing their digestive tracts.Nutrient dilution, which occurs when plastics displace food in the gut, affects the nutrient gain and consequently the growth of sea turtles.[ Ingestion of marine debris and slowed nutrient gain leads to increased time for sexual maturation that may affect future reproductive behaviors.[63] These turtles have the highest risk of encountering and ingesting plastic bags offshore of San Francisco Bay, the Columbia River mouth, and Puget Sound.

  

The leatherback turtle is a species with a cosmopolitan global range. Of all the extant sea turtle species, D. coriacea has the widest distribution, reaching as far north as Alaska and Norway and as far south as Cape Agulhas in Africa and the southernmost tip of New Zealand.[20] The leatherback is found in all tropical and subtropical oceans, and its range extends well into the Arctic Circle.

 

The three major, genetically distinct populations occur in the Atlantic, eastern Pacific, and western Pacific Oceans.[ While nesting beaches have been identified in the region, leatherback populations in the Indian Ocean remain generally unassessed and unevaluated.

 

Recent estimates of global nesting populations are that 26,000 to 43,000 females nest annually, which is a dramatic decline from the 115,000 estimated in 1980.

 

Atlantic subpopulation

The leatherback turtle population in the Atlantic Ocean ranges across the entire region. They range as far north as the North Sea and to the Cape of Good Hope in the south. Unlike other sea turtles, leatherback feeding areas are in colder waters, where an abundance of their jellyfish prey is found, which broadens their range. However, only a few beaches on both sides of the Atlantic provide nesting sites.

 

Off the Atlantic coast of Canada, leatherback turtles feed in the Gulf of Saint Lawrence near Quebec and as far north as Newfoundland and Labrador.[47] The most significant Atlantic nesting sites are in Suriname, Guyana, French Guiana in South America, Antigua and Barbuda, and Trinidad and Tobago in the Caribbean, and Gabon in Central Africa. The beaches of Mayumba National Park in Mayumba, Gabon, host the largest nesting population on the African continent and possibly worldwide, with nearly 30,000 turtles visiting its beaches each year between October and April. Off the northeastern coast of the South American continent, a few select beaches between French Guiana and Suriname are primary nesting sites of several species of sea turtles, the majority being leatherbacks. A few hundred nest annually on the eastern coast of Florida.[6] In Costa Rica, the beaches of Gandoca and Parismina provide nesting grounds.

 

Pacific subpopulation

Pacific leatherbacks divide into two populations. One population nests on beaches in Papua, Indonesia, and the Solomon Islands, and forages across the Pacific in the Northern Hemisphere, along the coasts of California, Oregon, and Washington in North America. The eastern Pacific population forages in the Southern Hemisphere, in waters along the western coast of South America, nesting in Mexico, Panama, El Salvador, Nicaragua, and Costa Rica,as well as eastern Australia.

 

The continental United States offers two major Pacific leatherback feeding areas. One well-studied area is just off the northwestern coast near the mouth of the Columbia River. The other American area is located in California.[50] Further north, off the Pacific coast of Canada, leatherbacks visit the beaches of British Columbia.

 

Estimates by the WWF suggest only 2,300 adult females of the Pacific leatherback remain, making it the most endangered marine turtle subpopulation.

 

South China Sea subpopulation

A third possible Pacific subpopulation has been proposed, those that nest in Malaysia. This subpopulation, however, has effectively been eradicated. The beach of Rantau Abang in Terengganu, Malaysia, once had the largest nesting population in the world, hosting 10,000 nests per year. The major cause of the decline was egg consumption by humans. Conservation efforts initiated in the 1960s were ineffective because they involved excavating and incubating eggs at artificial sites which inadvertently exposed the eggs to high temperatures. It only became known in the 1980s that sea turtles undergo temperature-dependent sex determination; it is suspected that nearly all the artificially incubated hatchlings were female.[53] In 2008, two turtles nested at Rantau Abang, and unfortunately, the eggs were infertile. Additionally, there are small nesting sites in southern Thailand where 18 turtles nested in 2021

 

Indian Ocean subpopulation

While little research has been done on Dermochelys populations in the Indian Ocean, nesting populations are known from Sri Lanka and the Nicobar Islands. These turtles are proposed to form a separate, genetically distinct Indian Ocean subpopulation.[

  

Lifespan

Very little is known of the species' lifespan. Some reports claim "30 years or more", while others state "50 years or more".Upper estimates exceed 100 years.

 

Death and decomposition

Dead leatherbacks that wash ashore are microecosystems while decomposing. In 1996, a drowned carcass held sarcophagid and calliphorid flies after being picked open by a pair of Coragyps atratus vultures. Infestation by carrion-eating beetles of the families Scarabaeidae, Carabidae, and Tenebrionidae soon followed. After days of decomposition, beetles from the families Histeridae and Staphylinidae and anthomyiid flies invaded the corpse, as well. Organisms from more than a dozen families took part in consuming the carcass.

  

Leatherback turtles face many predators in their early lives. Eggs may be preyed on by a diversity of coastal predators, including ghost crabs, monitor lizards, raccoons, coatis, dogs, coyotes, genets, mongooses, and shorebirds ranging from small plovers to large gulls. Many of the same predators feed on baby turtles as they try to get to the ocean, as well as frigatebirds and varied raptors. Once in the ocean, young leatherbacks still face predation from cephalopods, requiem sharks, and various large fish. Despite their lack of a hard shell, the huge adults face fewer serious predators, though they are occasionally overwhelmed and preyed on by very large marine predators such as killer whales, great white sharks, and tiger sharks. Nesting females have been preyed upon by jaguars in the American tropics.

 

The adult leatherback has been observed aggressively defending itself at sea from predators. A medium-sized adult was observed chasing a shark that had attempted to bite it and then turned its aggression and attacked the boat containing the humans observing the prior interaction.Dermochelys juveniles spend more of their time in tropical waters than do adults.

 

Adults are prone to long-distance migration. Migration occurs between the cold waters where mature leatherbacks feed, to the tropical and subtropical beaches in the regions where they hatch. In the Atlantic, females tagged in French Guiana have been recaptured on the other side of the ocean in Morocco and Spain.

  

Mating takes place at sea. Males never leave the water once they enter it, unlike females, which nest on land. After encountering a female (which possibly exudes a pheromone to signal her reproductive status), the male uses head movements, nuzzling, biting, or flipper movements to determine her receptiveness. Males can mate every year but the females mate every two to three years. Fertilization is internal, and multiple males usually mate with a single female. This polyandry does not provide the offspring with any special advantages. Female leatherbacks are known to nest up to 10 times in a single nesting season giving them the shortest internesting interval of all sea turtles.

   

One Day Pathétique (1.3 x 2.9 metres) is painted on doubly primed canvas in acrylic. The geometrical scaffolding is double Golden Rectangle between upper and lower strips as in Pablo PIcasso's "Guernica&quot, this being superimposed upon a Mediaeval . Muslim TiIe Art pattern (e.g. as in the Alhambra, Spain). Using naked female forms the painting reveals a joyful hopeful, dawn to night, "one day in the life of Pyotr Tchaikovsky" interpretation of his so-called Pathétique Symphony number 6 (he died several weeks after its first performance). Tchaikovsky was very happy with this symphony and the "one day" interpretation explains why - from the dreamy awaking in the morning to the gentle slide into sleep at the end of a happy day spent in Russian forests and meadows.

 

The nude female figures make a nice variation to the intrinsically .blob-and-line elements of Jackson Pollock's abstract expressionism. For detailed description and discussion of the "One Day Pathétique” painting see Gideon Polya, ““One Day Pathétique” Symphony Painting. HOPE – Best Renewables Now Cost Same as Coal Power”. For details of related paintings by Gideon Polya see "Art for Peace, Planet, Mother & Child": sites.google.com/site/artforpeaceplanetmotherchild/home .

 

I chanced upon the One Day" interpretation of Tchaikovsky's last Symphony number 6, the so-called Pathétique Symphony, while listening to the music as the sun rose over the beautiful Yarra River Valley, Meobourne, Australia. The soft opening was consitent with gentle awakrening and the memorable close when you struggle to hear thelast note was accordingly gently going off to sleep after a lovely day. - and in between the music variously describes sweeping grasslands, noon-day brilliance, the travails of our daily activities, late afternoon shadows, the brilliance of the stars ...

 

This optimistic interpretation has been used to garner optimism for our World threatened by man-made global warming. The technical solutions are already available - all that is lacking to save Humanity and the bIosphere is political will (see "Climate Crisis Facts & Required actions" c/- the Yarra Valley Climate Action Group : sites.google.com/site/yarravalleyclimateactiongroup/clima....

 

Thus Climate Emergency Actions URGENTLY Required are:

 

1. Change of societal philosophy to one of scientific risk management and biological sustainability with complete cessation of species extinctions and zero tolerance for lying.

 

2. Urgent reduction of atmospheric CO2 to a safe level of about 300 ppm as recommended by leading climate and biological scientists.

 

3. Rapid switch to the best non-carbon and renewable energy (solar, wind, geothermal, wave, tide and hydro options that are currently roughly the same market cost as coal-based power, and indeed much cheaper than the true cost, of coal burning-based power ) and to energy efficiency, public transport, needs-based production, re-afforestation and return of carbon as biochar to soils coupled with correspondingly rapid cessation of fossil fuel burning, deforestation, methanogenic livestock production and population growth (the latter cessations being driven by Carbon Taxes that demand payment from polluters of the real cost of GHG pollution).

 

For a recent expert and optimistic statement by top US climate scientist Professor James Hansen (Columbia University, NASA's GISS) see “It’s possible to avert the climate crisis”, Countercurrents, 29 November 2009: www.countercurrents.org ./hansen291109.htm .

Rock Pigeon or Rock Dove (Columba livia)

 

The rock dove (Columba livia) or rock pigeon is a member of the bird family Columbidae (doves and pigeons). In common usage, this bird is often simply referred to as the "pigeon".

 

The species includes the domestic pigeon (including the fancy pigeon), and escaped domestic pigeons have given rise to feral populations around the world.

 

Wild rock doves are pale grey with two black bars on each wing, while domestic and feral pigeons are very variable in colour and pattern. There are few visible differences between males and females. The species is generally monogamous, with two squabs (young) per brood. Both parents care for the young for a time.

 

Habitats include various open and semi-open environments. Cliffs and rock ledges are used for roosting and breeding in the wild. Originally found wild in Europe, North Africa, and western Asia, feral pigeons have become established in cities around the world. The species is abundant, with an estimated population of 17 to 28 million feral and wild birds in Europe.

  

Taxonomy and naming

 

The rock dove was first described by Gmelin in 1789.[8] The genus name Columba is the Latin word meaning "pigeon, dove", whose older etymology comes from the Ancient Greek κόλυμβος (kolumbos), "a diver", from κολυμβάω (kolumbao), "dive, plunge headlong, swim". Aristophanes (Birds, 304) and others use the word κολυμβίς (kolumbis), "diver", for the name of the bird, because of its swimming motion in the air. The specific epithet is derived from the Latin livor, "bluish". Its closest relative in the Columba genus is the hill pigeon, followed by the other rock pigeons: the snow, speckled and white-collared pigeons.

 

The species is also known as the rock pigeon or blue rock dove, the former being the official name from 2004 to 2011, at which point the IOC changed their official listing to its original British name of rock dove (styled as Rock Dove). In common usage, this bird is still often simply referred to as the "pigeon". Pigeon chicks are called squabs.

  

Subspecies[edit]

 

There are 12 subspecies recognised by Gibbs (2000); some of these may be derived from feral stock.

 

- C. l. livia, the nominate subspecies, occurs in western and southern Europe, northern Africa, and Asia to western Kazakhstan, the northern Caucasus, Georgia, Cyprus, Turkey, Iran, and Iraq.

 

- C. l. atlantis (Bannerman, 1931) of Madeira, the Azores and Cape Verde, is a very variable population with chequered upperparts obscuring the black wingbars, and is almost certainly derived from feral pigeons.

 

- C. l. canariensis (Bannerman, 1914) of the Canary Islands, is smaller and averages darker than the nominate subspecies.

 

- C. l. gymnocyclus (Gray, 1856) from Senegal and Guinea to Ghana, Benin and Nigeria is smaller and very much darker than nominate C. l. livia. It is almost blackish on the head, rump and underparts with a white back and the iridescence of the nape extending onto the head.

 

- C. l. targia (Geyr von Schweppenburg, 1916) breeds in the mountains of the Sahara east to Sudan. It is slightly smaller than the nominate form, with similar plumage, but the back is concolorous with the mantle instead of white.

 

- C. l. dakhlae (Richard Meinertzhagen, 1928) is confined to the two oases in central Egypt. It is smaller and much paler than the nominate subspecies.

 

- C. l. schimperi (Bonaparte, 1854) is found in the Nile Delta south to northern Sudan. It closely resembles C. l. targia, but has a distinctly paler mantle.

 

- C. l. palaestinae (Zedlitz, 1912) occurs from Syria to Sinai and Arabia. It is slightly larger than C. l. schimperi and has darker plumage.

 

- C. l. gaddi (Zarodney & Looudoni, 1906), breeds from Azerbaijan and Iran east to Uzbekistan is larger and paler than C. l. palaestinae with which it intergrades in the west. It also intergrades with the next subspecies to the east.

 

- C. l. neglecta (Hume, 1873), is found in the mountains of eastern Central Asia. It is similar to the nominate subspecies in size, but is darker with a stronger and more extensive iridescent sheen on the neck. It intergrades with the next race in the south.

 

- C. l. intermedia (Strickland, 1844) occurs in Sri Lanka and in India south of the Himalayan range of C. l. neglecta. It is similar to that subspecies, but darker with a less contrasting back.

 

- C. l. nigricans (Buturlin, 1908) in Mongolia and north China is variable and probably derived from feral stock.

  

Description

 

The adult of the nominate subspecies of the rock dove is 29 to 37 cm (11 to 15 in) long with a 62 to 72 cm (24 to 28 in) wingspan. Weight for wild or feral rock doves ranges from 238–380 g (8.4–13.4 oz), though overfed domestic and semi-domestic individuals can exceed normal weights. It has a dark bluish-gray head, neck, and chest with glossy yellowish, greenish, and reddish-purple iridescence along its neck and wing feathers. The iris is orange, red or golden with a paler inner ring, and the bare skin round the eye is bluish-grey. The bill is grey-black with a conspicuous off-white cere, and the feet are purplish-red. Among standard measurements, the wing chord is typically around 22.3 cm (8.8 in), the tail is 9.5 to 11 cm (3.7 to 4.3 in), the bill is around 1.8 cm (0.71 in) and the tarsus is 2.6 to 3.5 cm (1.0 to 1.4 in).

 

The adult female is almost identical to the male, but the iridescence on the neck is less intense and more restricted to the rear and sides, while that on the breast is often very obscure.

 

The white lower back of the pure rock dove is its best identification character; the two black bars on its pale grey wings are also distinctive. The tail has a black band on the end and the outer web of the tail feathers are margined with white. It is strong and quick on the wing, dashing out from sea caves, flying low over the water, its lighter grey rump showing well from above.

 

Young birds show little lustre and are duller. Eye colour of the pigeon is generally orange but a few pigeons may have white-grey eyes. The eyelids are orange in colour and are encapsulated in a grey-white eye ring. The feet are red to pink.

 

When circling overhead, the white underwing of the bird becomes conspicuous. In its flight, behaviour, and voice, which is more of a dovecot coo than the phrase of the wood pigeon, it is a typical pigeon. Although it is a relatively strong flier, it also glides frequently, holding its wings in a very pronounced V shape as it does. Though fields are visited for grain and green food, it is often not plentiful enough as to be a viewed as pest.

 

Pigeons feed on the ground in flocks or individually. They roost together in buildings or on walls or statues. When drinking, most birds take small sips and tilt their heads backwards to swallow the water. Pigeons are able to dip their bills into the water and drink continuously without having to tilt their heads back. When disturbed, a pigeon in a group will take off with a noisy clapping sound.

 

Pigeons, especially homing or carrier breeds, are well known for their ability to find their way home from long distances. Despite these demonstrated abilities, wild rock doves are sedentary and rarely leave their local areas.

  

Distribution and habitat

 

The rock dove has a restricted natural resident range in western and southern Europe, North Africa, and into South Asia. The rock dove is often found in pairs in the breeding season but is usually gregarious. The species (including ferals) has a large range, with an estimated global extent of occurrence of 10,000,000 km2 (3,900,000 sq mi). It has a large global population, including an estimated 17–28 million individuals in Europe. Fossil evidence suggests the rock dove originated in southern Asia and skeletal remains unearthed in Israel confirm their existence there for at least three hundred thousand years. However, this species has such a long history with humans that it is impossible to tell exactly where the species' original range was. Its habitat is natural cliffs, usually on coasts. Its domesticated form, the feral pigeon, has been widely introduced elsewhere, and is common, especially in cities, over much of the world. A rock pigeon's lifespan is anywhere from 3–5 years in the wild to 15 years in captivity, though longer-lived specimens have been reported. The main causes of mortality in the wild are predators and persecution by humans. The species was first introduced to North America in 1606 at Port Royal, Nova Scotia.

  

Reproduction

 

The rock dove breeds at any time of the year, but peak times are spring and summer. Nesting sites are along coastal cliff faces, as well as the artificial cliff faces created by apartment buildings with accessible ledges or roof spaces.

 

The nest is a flimsy platform of straw and sticks, laid on a ledge, under cover, often on the window ledges of buildings. Two white eggs are laid; incubation is shared by both parents lasting from seventeen to nineteen days. The newly hatched squab (nestling) has pale yellow down and a flesh-coloured bill with a dark band. For the first few days, the baby squab is tended and fed (through regurgitation) exclusively on "crop milk" (also called "pigeon milk" or "pigeon's milk"). The pigeon milk is produced in the crops of both parents in all species of pigeons and doves. The fledging period is about 30 days.

  

Predators

 

With only its flying abilities protecting it from predation, rock pigeons are a favorite almost around the world for a wide range of raptorial birds. In fact, with feral pigeons existing in almost every city in the world, they may form the majority of prey for several raptor species who live in urban areas. Peregrine falcons and Eurasian sparrowhawks are natural predators of pigeons that are quite adept at catching and feeding upon this species. Up to 80% of the diet of peregrine falcons in several cities that have breeding falcons is composed of feral pigeons. Some common predators of feral pigeons in North America are opossums, raccoons, red-tailed hawks, great horned owls, eastern screech owls and Accipiters. The birds that predate pigeons in North America can range in size from American kestrels to golden eagles and can even include gulls, crows, and ravens. On the ground the adults, their young and their eggs are at risk from feral and domestic cats. Doves and pigeons are considered to be game birds as many species have been hunted and used for food in many of the countries in which they are native.

  

Parasites

 

Pigeons may harbour a diverse parasite fauna. They often host the intestinal helminths Capillaria columbae and Ascaridia columbae. Their ectoparasites include the Ischnoceran lice Columbicola columbae, Campanulotes bidentatus compar, the Amblyceran lice Bonomiella columbae, Hohorstiella lata, Colpocephalum turbinatum, the mites Tinaminyssus melloi, Dermanyssus gallinae, Dermoglyphus columbae, Falculifer rostratus, and Diplaegidia columbae. The hippoboscid fly Pseudolynchia canariensis is a typical blood-sucking ectoparasite of pigeons, found only in tropical and sub-tropical regions.

  

Human health

 

Pigeons have been falsely associated with the spread of human diseases. Contact with pigeon droppings poses a minor risk of contracting histoplasmosis, cryptococcosis, and psittacosis, and exposure to both droppings and feathers can produce bird fancier's lung. Pigeons are not a major concern in the spread of West Nile virus; though they can contract it, they do not appear to be able to transmit it. Pigeons are, however, at potential risk for carrying and spreading avian influenza. One study has shown that adult pigeons are not clinically susceptible to the most dangerous strain of avian influenza, the H5N1, and that they did not transmit the virus to chickens. Other studies have presented evidence of clinical signs and neurological lesions resulting from infection, but found that the pigeons did not transmit the disease to chickens reared in direct contact with them. Pigeons were found to be "resistant or minimally susceptible" to other strains of avian influenza, such as the H7N7.

  

Domestication

 

Rock doves have been domesticated for several thousand years, giving rise to the domestic pigeon (Columba livia domestica). As well as food and pets, domesticated pigeons are used as homing pigeons. They were in the past also used as carrier pigeons, and so-called war pigeons have played significant roles during wartime, with many pigeons having received bravery awards and medals for their services in saving hundreds of human lives: including, notably, the British pigeon Cher Ami who received the Croix de Guerre for her heroic actions during World War I, and the Irish Paddy and the American G.I. Joe, who both received the Dickin Medal, amongst 32 pigeons to receive this medallion, for their gallant and brave actions during World War II. There are numerous breeds of fancy pigeons of all sizes, colours and types.

  

Feral pigeon

 

Many domestic birds have escaped or been released over the years, and have given rise to the feral pigeon. These show a variety of plumages, although some have the blue barred pattern as does the pure rock dove. Feral pigeons are found in large numbers in cities and towns all over the world. The scarcity of the pure wild species is partly due to interbreeding with feral birds.

  

Osmoregulation

 

Challenges

 

Water is taken in by the Columba livia directly by drinking water or indirectly from the food they ingest. They drink water through a process called double-suction mechanism. The daily diet of the Pigeon places many physiologically challenges it must over come through osmoregulation. Protein intake for example causes an excess toxins of amine groups when it is broken down for energy. To regulate this excess and secrete these unwanted toxins the Columba livia must remove the amine groups as uric acid. Nitrogen excretion through uric acid can be considered an advantage because it doesn't require a lot of water and isn't very soluble, but producing it takes more energy because of its complex molecular composition.

 

The danger of desiccation is a major threat to animals living on land. Water is lost in urine and feces, but evaporation is the principal route of water loss. Water lost must be replaced by drinking and water in food. Dehydration or salt-loading decreases the filtration rate primarily by the shut down of the nephrons, which is controlled by an antidiuretic hormone, arginine vasotocin. Pigeons adjust their drinking rates and food intake in parallel and when adequate water is unavailable for excretion, food intake is limited to maintain water balance. As Columbia livia inhabit arid environments, research attributes this to their strong flying capabilities to reach the available water sources, not because of exceptional potential for water conservation. Columba livia kidneys, like mammalian kidneys, are capable of producing urine hyperosmotic to the plasma utilizing the processes of filtration, reabsorption and secretion, which will be discussed later and explained through the Starling-Landis Hypothesis. The medullary cones function as countercurrent units that achieve the production of hyperosmotic urine. Hyperosmotic urine can be understood in light of the law of diffusion and osmolarity.

 

Organ of osmoregulation

 

Unlike a number other bird species which have the salt gland as the primary osmoregulatory organ, Columba livia does not use their salt gland even though it exists. Columba livia uses the function of their kidneys to maintain homeostatic balance of ions such as sodium and potassium while preserving water quantity in the body. Filtration of the blood, reabsorption of ions and water, and secretion of uric acid are all components of the kidney's process. The kidneys of Columba livia are located in its pelvic region. Columba livia has two kidneys that are coupled, each having three partially separate lobes; the posterior lobe is the largest in size. Like mammalian kidneys, the avian kidney contains a medullary region and a cortical region. Peripherally located around the cortical region, the collecting ducts gather into cone-like ducts, medullary cones, which converge into the ureters. There are two types of nephrons in the kidney; nephrons that are located in the cortex and do not contain the loop of Henle are called loopless nephrons, the other type are called looped or mammalian nephrons. Looped nephrons contain the loop of Henle that continue down into the medulla then enter the distal tubule drain towards the ureter. Mammals generally have a more vascularized glomeruli than the nephrons in birds. The nephrons of avian species can not produce urine that is hyperosmotic to the blood, but, the loop of Henle utilizes countercurrent multiplication which allows it to become hyperosmotic in the collecting duct. This alternation of permeability between different sections of the ascending and descending loop allows for the elevation of the urine osmotic pressure 2.5 times above the blood osmotic pressure.

  

Specialize cell types involved in osmoregulation

 

The integumentary system functions in osmoregulation by acting as a barrier between the extracellular compartment and the environment to regulate water gain and loss, as well as solute flux. The permeability of the integument to water and solutes varies from animal to animal.The excretory system is responsible for regulating water and solute levels in the body fluids. Pigeons can produce hyperosmotic urine but their renal system is different from other animals. They do not produce concentrated urine to reduce water loss but produce a whitish part called urate. It is considered as uric acid solid crystals and it is less toxic than urea. The wastes move from the blood of the peritubular capillaries passes through the tubule cells and into the collecting ducts and transported as urate (uric acid). Urate is then transported to the cloaca and from there to the large intestine where uric acid particle and water and solutes in the urine can be reabsorbed and balanced. Thus this allows them to save their body water instead of excreting large volume of dilute urea. Cells of the proximal tubule have numerous microvilli and mitochondria which provide surface area and energy to the proximal tubule cells.

 

The blood pH is regulated by the A and B types of cells located in distal tubule and collecting duct. The A type cells are acid secreting cells that have a proton ATPase in the apical membrane and a Cl-/ HCO3- exchange system in the basolateral membrane whereas, the B type cells are base secreting cells, which secrete bicarbonate into the lumen of the tubule in exchange for chloride ions. The regulation of pH in blood determines whether bicarbonate is reabsorbed or secreted.

 

Transport mechanisms of osmoregulation

 

The filtrate contains lots of important substances. In the proximal tubules of the Columbia livia kidney, substances that are needed, such as vitamins and glucose are reabsorbed into the blood. Their kidney has a variety of ion channels involved in salt and water transport. Water is reabsorbed through aquaporins which are present in the lumen of proximal tubule, basolateral membrane, and blood vessel near proximal tubule. Water flows from the epithelial cells into the blood via osmosis. Since osmosis occurs, the osmolarity of the filtrate remains isotonic. Sodium/Potassium/ATPase transporter is located in the basolateral membrane of the epithelial cell, which is opposite of the lumen of proximal tubule, and actively pumps sodium out of the cell into the blood.

  

Special adaptations

 

Eggshell's gas exchange and water loss

 

Gas exchange across eggshells results in water loss from the egg. However, the egg must retain enough water to hydrate the embryo. This results in the knowledge that changing temperatures and humidity can affect the eggshell's architecture. Behavioral adaptations in Columba livia and other birds, such as the incubation of their eggs, can help with the effects of these changing environments. It was found that eggshell architecture undergoes selection decoupled from behavioral effects, and that humidity may be a driving selective pressure. Low humidity requires enough water to keep the embryo from desiccation, and high humidity needs enough water loss to facilitate the initiation of pulmonary respiration. The water loss from the eggshell is directly linked to the growth rate of the species. The ability of the embryo to tolerate extreme water loss is due to the parental behavior in species colonizing in different environments. Studies have been done showing that wild habitats of Columba livia and other birds have a higher rate tolerance of various humidity levels, but Columba livia do prefer areas where the humidity closely matched their native breeding conditions. The pore areas of the shells allow water to diffuse in and out of the shell, preventing the possible harming of the embryo due to the high rates of water retention. If an eggshell is thinner, it can cause a decrease in pore length, and an increase in conductance and pore area. A thinner eggshell can also cause a decrease in mechanical restriction of the embryo.

  

Thermoregulation

 

Temperature changes

 

The Columbia Livia is habituated within many vast environments with varying degrees of temperatures. Like all vertebrates, Columbia Livia perspires heat through evaporation of water when temperatures are high in the environment. It’s preferred niche temperature ranges between +39 - +42 degrees Celsius.

 

Peripheral thermoreceptors of the Columbia Liva regulate its body’s response to the cold. During low temperatures, which put the Columbia Liva’s body under stress it accommodates extreme temperatures by increasing its internal temperatures within the core and spinal cord. Along with this increase, there is also a decrease in temperature within the legs, neck and back skin.

 

Physiological challenges placed on organism

 

Columba Livia stabilize their internal body temperature independent of alteration in ambient temperature. They are also able to withstand extreme climate conditions, such as ambient temperature range of +42 to -40 °C. The temperature regulation of Columba Livia is generally based on the principle of endotherms. Being endothermic they use metabolic heat to raise body temperature. Columba Livia are also homeotherms, meaning that they are thermoregulators and maintain a relatively constant body temperature. The heat exchange between animals and their surroundings occurs due to conduction, convection, radiation and evaporation. Fourier's Law of Heat Conduction describes the loss of heat experienced by animals through conduction. At low ambient temperatures the endothermic animals are able to reduce their heat loss by lowering the skin temperature and by increasing their peripheral insulation, which is discussed later.

 

Behavioral adaptations

 

Columba Livia does a few things to regulate its body temperature. Normally it will drink water after they have eaten, but when stressed by heat they can drink whenever needed to lower its body temperature. Another way it can regulate its heat is through Ptilomotor responses. Ptilomotor responses allow for better insulation of the body, because smooth muscle contractions make the feathers stand up straighter, which traps more air next to the skin. Columba Livia exhibits Ta (ambient temperature) selecting behavior. It will seek out its desired thermal neutral zone temperatures, in order to expend less energy heating and cooling its body.

 

Physiological changes to blood flow

 

Areas poorly or not insulated by feathers such as the beak, head, and feet have vasomotor responses. To reduce heat loss while in cold atmospheric temperatures, endothermic animals will lower the skin temperature by restricting the amount of blood that reaches it, called vasoconstriction. The sympathetic nervous system stimulates the constriction of the vascular beds at low temperatures. Vasodilation does the opposite; to increase the heat lost by convection after high muscular activity or from heat stress, Columba Livia increases its blood flow to the surface of its body. Cutaneous tissue of the beak, feet, and bends in the wings are dilated. To regulate brain temperature it uses the vascular vessels(plexus) in the eyes, in combination with vasomotion. Evaporation is usually controlled by sweat glands, however, birds use their breathing pattern to control heat dissipation. The frequency in breathing depends on body temperature, Tb; to increase respiratory evaporation the bird's breathing rate would increase. The most important thermoregulatory mechanism is called shivering thermogenesis. The skeletal muscles are used to generate heat through contractions when the surrounding air, Ta, is below its thermal neutral zone. As the temperature drops, the shivering increases to generate more heat. Non-shivering thermogenesis is used by Columba Livia, when exposed to cold to generate heat; an increase in Na+/K+-ATPase activity drives this mechanism in the liver.

 

Special adaptations

 

A study was done by Michael E. Rashotte, et al. (1998) comparing the vigilance states and body temperature is different within in fed and fasted pigeons (Columba Livia). Fasting induces nocturnal hypothermia in pigeons. There are different sleep patterns associated with heat production in pigeons, slow wave sleep (SWS) and paradoxical sleep (PS). An increase of SWS and PS was compared to the fasting-induced nocturnal hypothermia by comparing body temperature (Tb) and vigilance states when pigeons were fed and fasted. It was found that the Tb was decreasing near the beginning of the dark phase and that the time spent in SWS and PS was elevated in the fasting pigeons due to the increase of frequency and duration. When body temperature was low in the middle of the dark phase, it showed that SWS was elevated but it did not affect the PS stage. When the body temperature was high during the last hours of dark, SWS remained elevated in fasting-induced and that PS was relatively high. Rashotte, et al. (1998) suggests that more evidence is needed to confirm these results but he suggests that pigeons may be best viewed as an animal that has a shallow hypometabolic state that fall within (or very close to) their euthermic range. It is also seen that a pigeon’s vigilance stage can be compared similarly to mammals in hibernation.

 

Specialized organs or anatomy involved in thermoregulation

 

The purpose of thermoregulation is to maintain body temperature by producing heat through physiological and metabolic reactions. Heat gain should equal to rates of heat loss. If the body temperature is unbalanced, the animal becomes either warmer or colder. Heat production in birds is associated to shivering. The large flight muscles- pectoralis as well as the leg muscles generate heat by shivering.

 

Columba Livia have strong wings with flexible feathers which provide enough insulation to keep their body warm and dry. The fat layers and feathers reduce the flow of heat between an animal and its environment and lower the energy cost of keeping warm. In some birds the heat loss from the legs and feet is limited in cold weather because of a countercurrent mechanism that saves heat and in hot weather it can serve as heat radiators which increase blood flow.

 

Thermoregulation in birds requires cooling as well as warming. At low temperature birds can tuck head and neck under their wings to reduce heat loss. The heat is lost by the pigeons as an insensible heat by evaporation of water from the respiratory system and skin when temperature gradient is less and relative humidity is low. At the relatively high temperature birds increase their respiration rate to increase their cooling by evaporation. The panting is important in birds which involves gular flutter. The pouch richly supplied with blood vessels in the floor of the mouth; the rapid movement of the upper throat tissues - fluttering the pouch increases evaporation. Pigeons can use evaporative cooling to keep body temperature close to 40 °C in air temperatures as high as 60 °C, as long as they have sufficient water.

 

Also from previous studies experiment shows that a bird is capable of evaporating enough water from the cloaca for thermoregulation and results suggests that some birds’ cloacal evaporation can be controlled and could serve as an important maneuver for thermoregulation at high ambient temperatures.

 

Regulation of metabolism

 

Columba livia as homeothermic animals, are able to regulate heat production and external heat loss in autonomic ways, by a feedback control system. Negative feedback is the most important principle for regulation; a decrease of ambient temperature evoked by cold activates some thermoregulatory effector mechanisms, which reduce the heat loss and increase the internal heat production. The metabolic rate of resting Columba Livia at neutral ambient temperature, is reduced by a level of 5-10% during drowsiness, sleep and darkness. An increase follows every kind of muscle activity, such as flying, which increases metabolic rate by 10-12 times. Heat production throughout the day contributes to a high level of body temperature.

 

[Credit: en.wikipedia.org/]

 

legs? yes hummingbirds have legs.

They have a network of veins and arteries called a rete mirabile, a countercurrent mechanism that keeps much of the heat in the bird rather than losing it to the cold, providing just enough heat to keep the legs and feet from freezing.

 

this particular bird sent her legs to Brasil to get warm.

 

Rock Pigeon or Rock Dove (Columba livia) @ Taiwan

 

The rock dove (Columba livia) or rock pigeon is a member of the bird family Columbidae (doves and pigeons). In common usage, this bird is often simply referred to as the "pigeon".

 

The species includes the domestic pigeon (including the fancy pigeon), and escaped domestic pigeons have given rise to feral populations around the world.

 

Wild rock doves are pale grey with two black bars on each wing, while domestic and feral pigeons are very variable in colour and pattern. There are few visible differences between males and females. The species is generally monogamous, with two squabs (young) per brood. Both parents care for the young for a time.

 

Habitats include various open and semi-open environments. Cliffs and rock ledges are used for roosting and breeding in the wild. Originally found wild in Europe, North Africa, and western Asia, feral pigeons have become established in cities around the world. The species is abundant, with an estimated population of 17 to 28 million feral and wild birds in Europe.

  

Taxonomy and naming

 

The rock dove was first described by Gmelin in 1789.[8] The genus name Columba is the Latin word meaning "pigeon, dove", whose older etymology comes from the Ancient Greek κόλυμβος (kolumbos), "a diver", from κολυμβάω (kolumbao), "dive, plunge headlong, swim". Aristophanes (Birds, 304) and others use the word κολυμβίς (kolumbis), "diver", for the name of the bird, because of its swimming motion in the air. The specific epithet is derived from the Latin livor, "bluish". Its closest relative in the Columba genus is the hill pigeon, followed by the other rock pigeons: the snow, speckled and white-collared pigeons.

 

The species is also known as the rock pigeon or blue rock dove, the former being the official name from 2004 to 2011, at which point the IOC changed their official listing to its original British name of rock dove (styled as Rock Dove). In common usage, this bird is still often simply referred to as the "pigeon". Pigeon chicks are called squabs.

  

Subspecies[edit]

 

There are 12 subspecies recognised by Gibbs (2000); some of these may be derived from feral stock.

 

- C. l. livia, the nominate subspecies, occurs in western and southern Europe, northern Africa, and Asia to western Kazakhstan, the northern Caucasus, Georgia, Cyprus, Turkey, Iran, and Iraq.

 

- C. l. atlantis (Bannerman, 1931) of Madeira, the Azores and Cape Verde, is a very variable population with chequered upperparts obscuring the black wingbars, and is almost certainly derived from feral pigeons.

 

- C. l. canariensis (Bannerman, 1914) of the Canary Islands, is smaller and averages darker than the nominate subspecies.

 

- C. l. gymnocyclus (Gray, 1856) from Senegal and Guinea to Ghana, Benin and Nigeria is smaller and very much darker than nominate C. l. livia. It is almost blackish on the head, rump and underparts with a white back and the iridescence of the nape extending onto the head.

 

- C. l. targia (Geyr von Schweppenburg, 1916) breeds in the mountains of the Sahara east to Sudan. It is slightly smaller than the nominate form, with similar plumage, but the back is concolorous with the mantle instead of white.

 

- C. l. dakhlae (Richard Meinertzhagen, 1928) is confined to the two oases in central Egypt. It is smaller and much paler than the nominate subspecies.

 

- C. l. schimperi (Bonaparte, 1854) is found in the Nile Delta south to northern Sudan. It closely resembles C. l. targia, but has a distinctly paler mantle.

 

- C. l. palaestinae (Zedlitz, 1912) occurs from Syria to Sinai and Arabia. It is slightly larger than C. l. schimperi and has darker plumage.

 

- C. l. gaddi (Zarodney & Looudoni, 1906), breeds from Azerbaijan and Iran east to Uzbekistan is larger and paler than C. l. palaestinae with which it intergrades in the west. It also intergrades with the next subspecies to the east.

 

- C. l. neglecta (Hume, 1873), is found in the mountains of eastern Central Asia. It is similar to the nominate subspecies in size, but is darker with a stronger and more extensive iridescent sheen on the neck. It intergrades with the next race in the south.

 

- C. l. intermedia (Strickland, 1844) occurs in Sri Lanka and in India south of the Himalayan range of C. l. neglecta. It is similar to that subspecies, but darker with a less contrasting back.

 

- C. l. nigricans (Buturlin, 1908) in Mongolia and north China is variable and probably derived from feral stock.

  

Description

 

The adult of the nominate subspecies of the rock dove is 29 to 37 cm (11 to 15 in) long with a 62 to 72 cm (24 to 28 in) wingspan. Weight for wild or feral rock doves ranges from 238–380 g (8.4–13.4 oz), though overfed domestic and semi-domestic individuals can exceed normal weights. It has a dark bluish-gray head, neck, and chest with glossy yellowish, greenish, and reddish-purple iridescence along its neck and wing feathers. The iris is orange, red or golden with a paler inner ring, and the bare skin round the eye is bluish-grey. The bill is grey-black with a conspicuous off-white cere, and the feet are purplish-red. Among standard measurements, the wing chord is typically around 22.3 cm (8.8 in), the tail is 9.5 to 11 cm (3.7 to 4.3 in), the bill is around 1.8 cm (0.71 in) and the tarsus is 2.6 to 3.5 cm (1.0 to 1.4 in).

 

The adult female is almost identical to the male, but the iridescence on the neck is less intense and more restricted to the rear and sides, while that on the breast is often very obscure.

 

The white lower back of the pure rock dove is its best identification character; the two black bars on its pale grey wings are also distinctive. The tail has a black band on the end and the outer web of the tail feathers are margined with white. It is strong and quick on the wing, dashing out from sea caves, flying low over the water, its lighter grey rump showing well from above.

 

Young birds show little lustre and are duller. Eye colour of the pigeon is generally orange but a few pigeons may have white-grey eyes. The eyelids are orange in colour and are encapsulated in a grey-white eye ring. The feet are red to pink.

 

When circling overhead, the white underwing of the bird becomes conspicuous. In its flight, behaviour, and voice, which is more of a dovecot coo than the phrase of the wood pigeon, it is a typical pigeon. Although it is a relatively strong flier, it also glides frequently, holding its wings in a very pronounced V shape as it does. Though fields are visited for grain and green food, it is often not plentiful enough as to be a viewed as pest.

 

Pigeons feed on the ground in flocks or individually. They roost together in buildings or on walls or statues. When drinking, most birds take small sips and tilt their heads backwards to swallow the water. Pigeons are able to dip their bills into the water and drink continuously without having to tilt their heads back. When disturbed, a pigeon in a group will take off with a noisy clapping sound.

 

Pigeons, especially homing or carrier breeds, are well known for their ability to find their way home from long distances. Despite these demonstrated abilities, wild rock doves are sedentary and rarely leave their local areas.

  

Distribution and habitat

 

The rock dove has a restricted natural resident range in western and southern Europe, North Africa, and into South Asia. The rock dove is often found in pairs in the breeding season but is usually gregarious. The species (including ferals) has a large range, with an estimated global extent of occurrence of 10,000,000 km2 (3,900,000 sq mi). It has a large global population, including an estimated 17–28 million individuals in Europe. Fossil evidence suggests the rock dove originated in southern Asia and skeletal remains unearthed in Israel confirm their existence there for at least three hundred thousand years. However, this species has such a long history with humans that it is impossible to tell exactly where the species' original range was. Its habitat is natural cliffs, usually on coasts. Its domesticated form, the feral pigeon, has been widely introduced elsewhere, and is common, especially in cities, over much of the world. A rock pigeon's lifespan is anywhere from 3–5 years in the wild to 15 years in captivity, though longer-lived specimens have been reported. The main causes of mortality in the wild are predators and persecution by humans. The species was first introduced to North America in 1606 at Port Royal, Nova Scotia.

  

Reproduction

 

The rock dove breeds at any time of the year, but peak times are spring and summer. Nesting sites are along coastal cliff faces, as well as the artificial cliff faces created by apartment buildings with accessible ledges or roof spaces.

 

The nest is a flimsy platform of straw and sticks, laid on a ledge, under cover, often on the window ledges of buildings. Two white eggs are laid; incubation is shared by both parents lasting from seventeen to nineteen days. The newly hatched squab (nestling) has pale yellow down and a flesh-coloured bill with a dark band. For the first few days, the baby squab is tended and fed (through regurgitation) exclusively on "crop milk" (also called "pigeon milk" or "pigeon's milk"). The pigeon milk is produced in the crops of both parents in all species of pigeons and doves. The fledging period is about 30 days.

  

Predators

 

With only its flying abilities protecting it from predation, rock pigeons are a favorite almost around the world for a wide range of raptorial birds. In fact, with feral pigeons existing in almost every city in the world, they may form the majority of prey for several raptor species who live in urban areas. Peregrine falcons and Eurasian sparrowhawks are natural predators of pigeons that are quite adept at catching and feeding upon this species. Up to 80% of the diet of peregrine falcons in several cities that have breeding falcons is composed of feral pigeons. Some common predators of feral pigeons in North America are opossums, raccoons, red-tailed hawks, great horned owls, eastern screech owls and Accipiters. The birds that predate pigeons in North America can range in size from American kestrels to golden eagles and can even include gulls, crows, and ravens. On the ground the adults, their young and their eggs are at risk from feral and domestic cats. Doves and pigeons are considered to be game birds as many species have been hunted and used for food in many of the countries in which they are native.

  

Parasites

 

Pigeons may harbour a diverse parasite fauna. They often host the intestinal helminths Capillaria columbae and Ascaridia columbae. Their ectoparasites include the Ischnoceran lice Columbicola columbae, Campanulotes bidentatus compar, the Amblyceran lice Bonomiella columbae, Hohorstiella lata, Colpocephalum turbinatum, the mites Tinaminyssus melloi, Dermanyssus gallinae, Dermoglyphus columbae, Falculifer rostratus, and Diplaegidia columbae. The hippoboscid fly Pseudolynchia canariensis is a typical blood-sucking ectoparasite of pigeons, found only in tropical and sub-tropical regions.

  

Human health

 

Pigeons have been falsely associated with the spread of human diseases. Contact with pigeon droppings poses a minor risk of contracting histoplasmosis, cryptococcosis, and psittacosis, and exposure to both droppings and feathers can produce bird fancier's lung. Pigeons are not a major concern in the spread of West Nile virus; though they can contract it, they do not appear to be able to transmit it. Pigeons are, however, at potential risk for carrying and spreading avian influenza. One study has shown that adult pigeons are not clinically susceptible to the most dangerous strain of avian influenza, the H5N1, and that they did not transmit the virus to chickens. Other studies have presented evidence of clinical signs and neurological lesions resulting from infection, but found that the pigeons did not transmit the disease to chickens reared in direct contact with them. Pigeons were found to be "resistant or minimally susceptible" to other strains of avian influenza, such as the H7N7.

  

Domestication

 

Rock doves have been domesticated for several thousand years, giving rise to the domestic pigeon (Columba livia domestica). As well as food and pets, domesticated pigeons are used as homing pigeons. They were in the past also used as carrier pigeons, and so-called war pigeons have played significant roles during wartime, with many pigeons having received bravery awards and medals for their services in saving hundreds of human lives: including, notably, the British pigeon Cher Ami who received the Croix de Guerre for her heroic actions during World War I, and the Irish Paddy and the American G.I. Joe, who both received the Dickin Medal, amongst 32 pigeons to receive this medallion, for their gallant and brave actions during World War II. There are numerous breeds of fancy pigeons of all sizes, colours and types.

  

Feral pigeon

 

Many domestic birds have escaped or been released over the years, and have given rise to the feral pigeon. These show a variety of plumages, although some have the blue barred pattern as does the pure rock dove. Feral pigeons are found in large numbers in cities and towns all over the world. The scarcity of the pure wild species is partly due to interbreeding with feral birds.

  

Osmoregulation

 

Challenges

 

Water is taken in by the Columba livia directly by drinking water or indirectly from the food they ingest. They drink water through a process called double-suction mechanism. The daily diet of the Pigeon places many physiologically challenges it must over come through osmoregulation. Protein intake for example causes an excess toxins of amine groups when it is broken down for energy. To regulate this excess and secrete these unwanted toxins the Columba livia must remove the amine groups as uric acid. Nitrogen excretion through uric acid can be considered an advantage because it doesn't require a lot of water and isn't very soluble, but producing it takes more energy because of its complex molecular composition.

 

The danger of desiccation is a major threat to animals living on land. Water is lost in urine and feces, but evaporation is the principal route of water loss. Water lost must be replaced by drinking and water in food. Dehydration or salt-loading decreases the filtration rate primarily by the shut down of the nephrons, which is controlled by an antidiuretic hormone, arginine vasotocin. Pigeons adjust their drinking rates and food intake in parallel and when adequate water is unavailable for excretion, food intake is limited to maintain water balance. As Columbia livia inhabit arid environments, research attributes this to their strong flying capabilities to reach the available water sources, not because of exceptional potential for water conservation. Columba livia kidneys, like mammalian kidneys, are capable of producing urine hyperosmotic to the plasma utilizing the processes of filtration, reabsorption and secretion, which will be discussed later and explained through the Starling-Landis Hypothesis. The medullary cones function as countercurrent units that achieve the production of hyperosmotic urine. Hyperosmotic urine can be understood in light of the law of diffusion and osmolarity.

 

Organ of osmoregulation

 

Unlike a number other bird species which have the salt gland as the primary osmoregulatory organ, Columba livia does not use their salt gland even though it exists. Columba livia uses the function of their kidneys to maintain homeostatic balance of ions such as sodium and potassium while preserving water quantity in the body. Filtration of the blood, reabsorption of ions and water, and secretion of uric acid are all components of the kidney's process. The kidneys of Columba livia are located in its pelvic region. Columba livia has two kidneys that are coupled, each having three partially separate lobes; the posterior lobe is the largest in size. Like mammalian kidneys, the avian kidney contains a medullary region and a cortical region. Peripherally located around the cortical region, the collecting ducts gather into cone-like ducts, medullary cones, which converge into the ureters. There are two types of nephrons in the kidney; nephrons that are located in the cortex and do not contain the loop of Henle are called loopless nephrons, the other type are called looped or mammalian nephrons. Looped nephrons contain the loop of Henle that continue down into the medulla then enter the distal tubule drain towards the ureter. Mammals generally have a more vascularized glomeruli than the nephrons in birds. The nephrons of avian species can not produce urine that is hyperosmotic to the blood, but, the loop of Henle utilizes countercurrent multiplication which allows it to become hyperosmotic in the collecting duct. This alternation of permeability between different sections of the ascending and descending loop allows for the elevation of the urine osmotic pressure 2.5 times above the blood osmotic pressure.

  

Specialize cell types involved in osmoregulation

 

The integumentary system functions in osmoregulation by acting as a barrier between the extracellular compartment and the environment to regulate water gain and loss, as well as solute flux. The permeability of the integument to water and solutes varies from animal to animal.The excretory system is responsible for regulating water and solute levels in the body fluids. Pigeons can produce hyperosmotic urine but their renal system is different from other animals. They do not produce concentrated urine to reduce water loss but produce a whitish part called urate. It is considered as uric acid solid crystals and it is less toxic than urea. The wastes move from the blood of the peritubular capillaries passes through the tubule cells and into the collecting ducts and transported as urate (uric acid). Urate is then transported to the cloaca and from there to the large intestine where uric acid particle and water and solutes in the urine can be reabsorbed and balanced. Thus this allows them to save their body water instead of excreting large volume of dilute urea. Cells of the proximal tubule have numerous microvilli and mitochondria which provide surface area and energy to the proximal tubule cells.

 

The blood pH is regulated by the A and B types of cells located in distal tubule and collecting duct. The A type cells are acid secreting cells that have a proton ATPase in the apical membrane and a Cl-/ HCO3- exchange system in the basolateral membrane whereas, the B type cells are base secreting cells, which secrete bicarbonate into the lumen of the tubule in exchange for chloride ions. The regulation of pH in blood determines whether bicarbonate is reabsorbed or secreted.

 

Transport mechanisms of osmoregulation

 

The filtrate contains lots of important substances. In the proximal tubules of the Columbia livia kidney, substances that are needed, such as vitamins and glucose are reabsorbed into the blood. Their kidney has a variety of ion channels involved in salt and water transport. Water is reabsorbed through aquaporins which are present in the lumen of proximal tubule, basolateral membrane, and blood vessel near proximal tubule. Water flows from the epithelial cells into the blood via osmosis. Since osmosis occurs, the osmolarity of the filtrate remains isotonic. Sodium/Potassium/ATPase transporter is located in the basolateral membrane of the epithelial cell, which is opposite of the lumen of proximal tubule, and actively pumps sodium out of the cell into the blood.

  

Special adaptations

 

Eggshell's gas exchange and water loss

 

Gas exchange across eggshells results in water loss from the egg. However, the egg must retain enough water to hydrate the embryo. This results in the knowledge that changing temperatures and humidity can affect the eggshell's architecture. Behavioral adaptations in Columba livia and other birds, such as the incubation of their eggs, can help with the effects of these changing environments. It was found that eggshell architecture undergoes selection decoupled from behavioral effects, and that humidity may be a driving selective pressure. Low humidity requires enough water to keep the embryo from desiccation, and high humidity needs enough water loss to facilitate the initiation of pulmonary respiration. The water loss from the eggshell is directly linked to the growth rate of the species. The ability of the embryo to tolerate extreme water loss is due to the parental behavior in species colonizing in different environments. Studies have been done showing that wild habitats of Columba livia and other birds have a higher rate tolerance of various humidity levels, but Columba livia do prefer areas where the humidity closely matched their native breeding conditions. The pore areas of the shells allow water to diffuse in and out of the shell, preventing the possible harming of the embryo due to the high rates of water retention. If an eggshell is thinner, it can cause a decrease in pore length, and an increase in conductance and pore area. A thinner eggshell can also cause a decrease in mechanical restriction of the embryo.

  

Thermoregulation

 

Temperature changes

 

The Columbia Livia is habituated within many vast environments with varying degrees of temperatures. Like all vertebrates, Columbia Livia perspires heat through evaporation of water when temperatures are high in the environment. It’s preferred niche temperature ranges between +39 - +42 degrees Celsius.

 

Peripheral thermoreceptors of the Columbia Liva regulate its body’s response to the cold. During low temperatures, which put the Columbia Liva’s body under stress it accommodates extreme temperatures by increasing its internal temperatures within the core and spinal cord. Along with this increase, there is also a decrease in temperature within the legs, neck and back skin.

 

Physiological challenges placed on organism

 

Columba Livia stabilize their internal body temperature independent of alteration in ambient temperature. They are also able to withstand extreme climate conditions, such as ambient temperature range of +42 to -40 °C. The temperature regulation of Columba Livia is generally based on the principle of endotherms. Being endothermic they use metabolic heat to raise body temperature. Columba Livia are also homeotherms, meaning that they are thermoregulators and maintain a relatively constant body temperature. The heat exchange between animals and their surroundings occurs due to conduction, convection, radiation and evaporation. Fourier's Law of Heat Conduction describes the loss of heat experienced by animals through conduction. At low ambient temperatures the endothermic animals are able to reduce their heat loss by lowering the skin temperature and by increasing their peripheral insulation, which is discussed later.

 

Behavioral adaptations

 

Columba Livia does a few things to regulate its body temperature. Normally it will drink water after they have eaten, but when stressed by heat they can drink whenever needed to lower its body temperature. Another way it can regulate its heat is through Ptilomotor responses. Ptilomotor responses allow for better insulation of the body, because smooth muscle contractions make the feathers stand up straighter, which traps more air next to the skin. Columba Livia exhibits Ta (ambient temperature) selecting behavior. It will seek out its desired thermal neutral zone temperatures, in order to expend less energy heating and cooling its body.

 

Physiological changes to blood flow

 

Areas poorly or not insulated by feathers such as the beak, head, and feet have vasomotor responses. To reduce heat loss while in cold atmospheric temperatures, endothermic animals will lower the skin temperature by restricting the amount of blood that reaches it, called vasoconstriction. The sympathetic nervous system stimulates the constriction of the vascular beds at low temperatures. Vasodilation does the opposite; to increase the heat lost by convection after high muscular activity or from heat stress, Columba Livia increases its blood flow to the surface of its body. Cutaneous tissue of the beak, feet, and bends in the wings are dilated. To regulate brain temperature it uses the vascular vessels(plexus) in the eyes, in combination with vasomotion. Evaporation is usually controlled by sweat glands, however, birds use their breathing pattern to control heat dissipation. The frequency in breathing depends on body temperature, Tb; to increase respiratory evaporation the bird's breathing rate would increase. The most important thermoregulatory mechanism is called shivering thermogenesis. The skeletal muscles are used to generate heat through contractions when the surrounding air, Ta, is below its thermal neutral zone. As the temperature drops, the shivering increases to generate more heat. Non-shivering thermogenesis is used by Columba Livia, when exposed to cold to generate heat; an increase in Na+/K+-ATPase activity drives this mechanism in the liver.

 

Special adaptations

 

A study was done by Michael E. Rashotte, et al. (1998) comparing the vigilance states and body temperature is different within in fed and fasted pigeons (Columba Livia). Fasting induces nocturnal hypothermia in pigeons. There are different sleep patterns associated with heat production in pigeons, slow wave sleep (SWS) and paradoxical sleep (PS). An increase of SWS and PS was compared to the fasting-induced nocturnal hypothermia by comparing body temperature (Tb) and vigilance states when pigeons were fed and fasted. It was found that the Tb was decreasing near the beginning of the dark phase and that the time spent in SWS and PS was elevated in the fasting pigeons due to the increase of frequency and duration. When body temperature was low in the middle of the dark phase, it showed that SWS was elevated but it did not affect the PS stage. When the body temperature was high during the last hours of dark, SWS remained elevated in fasting-induced and that PS was relatively high. Rashotte, et al. (1998) suggests that more evidence is needed to confirm these results but he suggests that pigeons may be best viewed as an animal that has a shallow hypometabolic state that fall within (or very close to) their euthermic range. It is also seen that a pigeon’s vigilance stage can be compared similarly to mammals in hibernation.

 

Specialized organs or anatomy involved in thermoregulation

 

The purpose of thermoregulation is to maintain body temperature by producing heat through physiological and metabolic reactions. Heat gain should equal to rates of heat loss. If the body temperature is unbalanced, the animal becomes either warmer or colder. Heat production in birds is associated to shivering. The large flight muscles- pectoralis as well as the leg muscles generate heat by shivering.

 

Columba Livia have strong wings with flexible feathers which provide enough insulation to keep their body warm and dry. The fat layers and feathers reduce the flow of heat between an animal and its environment and lower the energy cost of keeping warm. In some birds the heat loss from the legs and feet is limited in cold weather because of a countercurrent mechanism that saves heat and in hot weather it can serve as heat radiators which increase blood flow.

 

Thermoregulation in birds requires cooling as well as warming. At low temperature birds can tuck head and neck under their wings to reduce heat loss. The heat is lost by the pigeons as an insensible heat by evaporation of water from the respiratory system and skin when temperature gradient is less and relative humidity is low. At the relatively high temperature birds increase their respiration rate to increase their cooling by evaporation. The panting is important in birds which involves gular flutter. The pouch richly supplied with blood vessels in the floor of the mouth; the rapid movement of the upper throat tissues - fluttering the pouch increases evaporation. Pigeons can use evaporative cooling to keep body temperature close to 40 °C in air temperatures as high as 60 °C, as long as they have sufficient water.

 

Also from previous studies experiment shows that a bird is capable of evaporating enough water from the cloaca for thermoregulation and results suggests that some birds’ cloacal evaporation can be controlled and could serve as an important maneuver for thermoregulation at high ambient temperatures.

 

Regulation of metabolism

 

Columba livia as homeothermic animals, are able to regulate heat production and external heat loss in autonomic ways, by a feedback control system. Negative feedback is the most important principle for regulation; a decrease of ambient temperature evoked by cold activates some thermoregulatory effector mechanisms, which reduce the heat loss and increase the internal heat production. The metabolic rate of resting Columba Livia at neutral ambient temperature, is reduced by a level of 5-10% during drowsiness, sleep and darkness. An increase follows every kind of muscle activity, such as flying, which increases metabolic rate by 10-12 times. Heat production throughout the day contributes to a high level of body temperature.

 

[Credit: en.wikipedia.org/]

   

My Country (1.3 x 2.9 metres) is painted in acrylic on doubly primed canvas. It is geometrically based on a Double Golden Rectangle between upper and lower strip borders as in Pablo Picasso's "Guernica" andsuperimposed upon a mediaeval Muslim Tile Art pattern.

 

The painting describes Dorothea McKellars's iconic Australian poem "My Country" ("I love a sunburnt country, a land of sweeping plains..."). It stretches from still substantial Indigenous Australian West, North and Central Australia (see the red rock of Uluru) through to the outback plains west of the Great Dividing Range and the urban east coast (skyscrapers, Sydney Harbor Bridge) and the Great Barrier Reef.

 

For the text of Dorothea Mackellar's poem "My Country" see "My Country": en.wikipedia.org/wiki/My_Country .For detailed discussion of the "My Country" painting see Gideon Polya, “”My Country” Painting & Poem. Australia – the Good, the Bad and the Ugly”: sites.google.com/site/artforpeaceplanetmotherchild/my-cou... . For details of related paintings see "Art for Peace, Planet, Mother & Child": sites.google.com/site/artforpeaceplanetmotherchild/home .

 

Before the European Invasion Australia had about 500 Indigenous groups speaking 250 languages. Only about 50 of these languages survive and White Australian policy is still dedicated (albeit now in a very "politiically correct" way) to destruction of Indigenous cultures.

 

Australia has a great variety of stunning landscapes and astonishing ecosystems from tropical wetlands to temperate rainforests. - but these too are being destroyed by the White Australian "look he other way" culture of greed. Thus the Murray River, Australia's major river, has become a LAKE and but for dam releases would merely be a succession of algal-infested ponds. The Murray Darling River System has been doomed by continuing White Australian greed.

 

Despite the evil of the Aboriginal Genocide, Australia led the World in decent social innovations a century ago. Thus Australia was one of the first countries in the world to have trade unions, free and compulsory education, public hospitals, public universities and women’s suffrage (GOOD). However Australia has an awful, BAD and UGLY history of over 2 centuries of active Aboriginal Genocide (the last massacres occurring in the 1920s); the Stolen Generations in which 0.1 million Aboriginal Children were forcibly removed from their mothers (this continuing up to the1970s); effective slavery that continued in the Pacific islands up to the 1920s (and on Australian Mainland pastoral properties up to the 1970s); loyal support for the horrors of British imperialism that caused 1.5 billion excess deaths in British-ruled India alone; continuing involvement in post-1950 US Asian Wars (with Indigenous excess deaths totalling 24 million) (see Gideon Polya, “”My Country” Painting & Poem. Australia – the Good, the Bad and the Ugly”: sites.google.com/site/artforpeaceplanetmotherchild/my-cou... ).

 

Australia has a continuing involvement in the ongoing Aboriginal Genocide, the Iraqi Genocide, the Afghan Genocide and the horrendously threatening Climate Genocide. Indeed the artist has made Formal Complaints To ICC re US Alliance Palestinian, Iraqi, Afghan, Muslim, Aboriginal, Biofuel and Climate Genocides (see Gideon Polya, "Complaint To ICC re US Alliance Palestinian, Iraqi, Afghan, Muslim, Aboriginal, Biofuel And Climate Genocides": www.countercurrents.org/polya090110.htm ).

The reindeer or caribou (Rangifer tarandus) is a species of deer with circumpolar distribution, native to Arctic, subarctic, tundra, boreal, and mountainous regions of Northern Europe, Siberia, and North America. It is the only representative of the genus Rangifer. More recent studies suggest the splitting of reindeer and caribou into six distinct species over their range.

 

Reindeer occur in both migratory and sedentary populations, and their herd sizes vary greatly in different regions. The tundra subspecies are adapted for extreme cold, and some are adapted for long-distance migration.

 

Reindeer vary greatly in size and color from the smallest, the Svalbard reindeer (R. (t.) platyrhynchus), to the largest, Osborn's caribou (R. t. osborni). Although reindeer are quite numerous, some species and subspecies are in decline and considered vulnerable. They are unique among deer (Cervidae) in that females may have antlers, although the prevalence of antlered females varies by species and subspecies.

 

Reindeer are the only successfully semi-domesticated deer on a large scale in the world. Both wild and domestic reindeer have been an important source of food, clothing, and shelter for Arctic people from prehistorical times. They are still herded and hunted today. In some traditional Christmas legends, Santa Claus's reindeer pull a sleigh through the night sky to help Santa Claus deliver gifts to good children on Christmas Eve.

 

Description

Names follow international convention before the recent revision[9] (see Taxonomy below). Reindeer/caribou (Rangifer) vary in size from the smallest, the Svalbard reindeer (R. (t.) platyrhynchus), to the largest, Osborn's caribou (R. t. osborni). They also vary in coat color and antler architecture.

 

The North American range of caribou extends from Alaska through the Yukon, the Northwest Territories and Nunavut throughout the tundra, taiga and boreal forest and south through the Canadian Rocky Mountains. Of the eight subspecies classified by Harding (2022) into the Arctic caribou (R. arcticus), the migratory mainland barren-ground caribou of Arctic Alaska and Canada (R. t. arcticus), summer in tundra and winter in taiga, a transitional forest zone between boreal forest and tundra; the nomadic Peary caribou (R. t. pearyi) lives in the polar desert of the High Arctic Archipelago and Grant's caribou (R. t. granti) lives in the western end of the Alaska Peninsula and the adjacent islands; the other four subspecies, Osborn's caribou (R. t. osborni), Stone's caribou (R. t. stonei), the Rocky Mountain caribou (R. t. fortidens) and the Selkirk Mountains caribou (R. t. montanus) are all montane. The extinct insular Queen Charlotte Islands caribou (R. t. dawsoni), lived on Graham Island in Haida Gwaii (formerly known as the Queen Charlotte Islands).

 

The boreal woodland caribou (R. t. caribou), lives in the boreal forest of northeastern Canada: the Labrador or Ungava caribou of northern Quebec and northern Labrador (R. t. caboti), and the Newfoundland caribou of Newfoundland (R. t. terranovae) have been found to be genetically in the woodland caribou lineage.

 

In Eurasia, both wild and domestic reindeer are distributed across the tundra and into the taiga. Eurasian mountain reindeer (R. t. tarandus) are close to North American caribou genetically and visually, but with sufficient differences to warrant division into two species. The unique, insular Svalbard reindeer inhabits the Svalbard Archipelago. The Finnish forest reindeer (R. t. fennicus) is spottily distributed in the coniferous forest zones from Finland to east of Lake Baikal: the Siberian forest reindeer (R. t. valentinae, formerly called the Busk Mountains reindeer (R. t. buskensis) by American taxonomists) occupies the Altai and Ural Mountains.

 

Male ("bull") and female ("cow") reindeer can grow antlers annually, although the proportion of females that grow antlers varies greatly between populations. Antlers are typically larger on males. Antler architecture varies by species and subspecies and, together with pelage differences, can often be used to distinguish between species and subspecies (see illustrations in Geist, 1991 and Geist, 1998).

 

Status

About 25,000 mountain reindeer (R. t. tarandus) still live in the mountains of Norway, notably in Hardangervidda. In Sweden there are approximately 250,000 reindeer in herds managed by Sami villages. Russia manages 19 herds of Siberian tundra reindeer (R. t. sibiricus) that total about 940,000. The Taimyr herd of Siberian tundra reindeer is the largest wild reindeer herd in the world, varying between 400,000 and 1,000,000; it is a metapopulation consisting of several subpopulations — some of which are phenotypically different — with different migration routes and calving areas. The Kamchatkan reindeer (R. t. phylarchus), a forest subspecies, formerly included reindeer west of the Sea of Okhotsk which, however, are indistinguishable genetically from the Jano-Indigirka, East Siberian taiga and Chukotka populations of R. t. sibiricus. Siberian tundra reindeer herds have been in decline but are stable or increasing since 2000.

 

Insular (island) reindeer, classified as the Novaya Zemlya reindeer (R. t. pearsoni) occupy several island groups: the Novaya Zemlya Archipelago (about 5,000 animals at last count, but most of these are either domestic reindeer or domestic-wild hybrids), the New Siberia Archipelago (about 10,000 to 15,000), and Wrangel Island (200 to 300 feral domestic reindeer).

 

What was once the second largest herd is the migratory Labrador caribou (R. t. caboti)[9] George River herd in Canada, with former variations between 28,000 and 385,000. As of January 2018, there are fewer than 9,000 animals estimated to be left in the George River herd, as reported by the Canadian Broadcasting Corporation. The New York Times reported in April 2018 of the disappearance of the only herd of southern mountain woodland caribou in the contiguous United States, with an expert calling it "functionally extinct" after the herd's size dwindled to a mere three animals. After the last individual, a female, was translocated to a wildlife rehabilitation center in Canada, caribou were considered extirpated from the contiguous United States. The Committee on Status of Endangered Wildlife in Canada (COSEWIC) classified both the Southern Mountain population DU9 (R. t. montanus) and the Central Mountain population DU8 (R. t. fortidens) as Endangered and the Northern Mountain population DU7 (R. t. osborni) as Threatened.

 

Some species and subspecies are rare and three subspecies have already become extinct: the Queen Charlotte Islands caribou (R. t. dawsoni) from western Canada, the Sakhalin reindeer (R. t. setoni) from Sakhalin and the East Greenland caribou from eastern Greenland, although some authorities believe that the latter, R. t. eogroenlandicus Degerbøl, 1957, is a junior synonym of the Peary caribou Historically, the range of the sedentary boreal woodland caribou covered more than half of Canada and into the northern states of the contiguous United States from Maine to Washington. Boreal woodland caribou have disappeared from most of their original southern range and were designated as Threatened in 2002 by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). Environment Canada reported in 2011 that there were approximately 34,000 boreal woodland caribou in 51 ranges remaining in Canada (Environment Canada, 2011b), although those numbers included montane populations classified by Harding (2022) into subspecies of the Arctic caribou. Siberian tundra reindeer herds are also in decline, and Rangifer as a whole is considered to be Vulnerable by the IUCN.

 

Naming

Charles Hamilton Smith is credited with the name Rangifer for the reindeer genus, which Albertus Magnus used in his De animalibus, fol. Liber 22, Cap. 268: "Dicitur Rangyfer quasi ramifer". This word may go back to the Sámi word raingo. Carl Linnaeus chose the word tarandus as the specific epithet, making reference to Ulisse Aldrovandi's Quadrupedum omnium bisulcorum historia fol. 859–863, Cap. 30: De Tarando (1621). However, Aldrovandi and Conrad Gessner thought that rangifer and tarandus were two separate animals, In any case, the tarandos name goes back to Aristotle and Theophrastus.

 

The use of the terms reindeer and caribou for essentially the same animal can cause confusion, but the International Union for Conservation of Nature clearly delineates the issue: "Reindeer is the European name for the species of Rangifer, while in North America, Rangifer species are known as Caribou." The word reindeer is an anglicized version of the Old Norse words hreinn (“reindeer”) and dýr (“animal”) and has nothing to do with reins. The word caribou comes through French, from the Mi'kmaq qalipu, meaning "snow shoveler", and refers to its habit of pawing through the snow for food.

 

Because of its importance to many cultures, Rangifer and some of its species and subspecies have names in many languages. Inuvaluit of the western Canadian Arctic and Inuit of the eastern Canadian Arctic, who speak different dialects of Inuktitut, both call the barren-ground caribou tuktu. The Wekʼèezhìi people, a Dene (Athapascan) group, call the Arctic caribou ekwǫ̀ and the boreal woodland caribou tǫdzı. The Gwichʼin (also a Dene group) have over 24 distinct caribou-related words.

 

Reindeer are also called tuttu by the Greenlandic Inuit and hreindýr, sometimes rein, by the Icelanders.

 

Evolution

The "glacial-interglacial cycles of the upper Pleistocene had a major influence on the evolution" of Rangifer species and other Arctic and sub-Arctic species. Isolation of tundra-adapted species Rangifer in Last Glacial Maximum refugia during the last glacial – the Wisconsin glaciation in North America and the Weichselian glaciation in Eurasia – shaped "intraspecific genetic variability" particularly between the North American and Eurasian parts of the Arctic.

 

Reindeer/caribou (Rangifer) are in the subfamily Odocoileinae, along with roe deer (Capreolus), Eurasian elk/moose (Alces), and water deer (Hydropotes). These antlered cervids split from the horned ruminants Bos (cattle and yaks), Ovis (sheep) and Capra (goats) about 36 million years ago. The Eurasian clade of Odocoileinae (Capreolini, Hydropotini and Alcini) split from the New World tribes of Capreolinae (Odocoileini and Rangiferini) in the Late Miocene, 8.7–9.6 million years ago. Rangifer “evolved as a mountain deer, ...exploiting the subalpine and alpine meadows...”. Rangifer originated in the Late Pliocene and diversified in the Early Pleistocene, a 2+ million-year period of multiple glacier advances and retreats. Several named Rangifer fossils in Eurasia and North America predate the evolution of modern tundra reindeer.

 

Archaeologists distinguish “modern” tundra reindeer and barren-ground caribou from primitive forms — living and extinct — that did not have adaptations to extreme cold and to long distance migration. They include a broad, high muzzle to increase the volume of the nasal cavity to warm and moisten the air before it enters the throat and lungs, bez tines set close to the brow tines, distinctive coat patterns, short legs and other adaptations for running long distances, and multiple behaviors suited to tundra, but not to forest (such as synchronized calving and aggregation during rutting and post-calving). As well, many genes, including those for vitamin D metabolism, fat metabolism, retinal development, circadian rhythm, and tolerance to cold temperatures, are found in tundra caribou that are lacking or rudimentary in forest types. For this reason, forest-adapted reindeer and caribou could not survive in tundra or polar deserts. The oldest undoubted Rangifer fossil is from Omsk, Russia, dated to 2.1-1.8 Ma. The oldest North American Rangifer fossil is from the Yukon, 1.6 million years before present (BP). A fossil skull fragment from Süßenborn, Germany, R. arcticus stadelmanni, (which is probably misnamed) with “rather thin and cylinder-shaped” antlers, dates to the Middle Pleistocene (Günz) Period, 680,000-620,000 BP. Rangifer fossils become increasingly frequent in circumpolar deposits beginning with the Riss glaciations, the second youngest of the Pleistocene Epoch, roughly 300,000–130,000 BP. By the 4-Würm period (110,000–70,000 to 12,000–10,000 BP), its European range was extensive, supplying a major food source for prehistoric Europeans. North American fossils outside of Beringia that predate the Last Glacial Maximum (LGM) are of Rancholabrean age (240,000–11,000 years BP) and occur along the fringes of the Rocky Mountain and Laurentide ice sheets as far south as northern Alabama; and in Sangamonian deposits (~100,000 years BP) from western Canada.

 

A R. t. pearyi-sized caribou occupied Greenland before and after the LGM and persisted in a relict enclave in northeastern Greenland until it went extinct about 1900 (see discussion of R. t. eogroenlandicus below). Archaeological excavations showed that larger barren-ground-sized caribou appeared in western Greenland about 4,000 years ago.

 

The late Valerius Geist (1998) dates the Eurasian reindeer radiation dates to the large Riss glaciation (347,000 to 128,000 years ago), based on the Norwegian-Svalbard split 225,000 years ago. Finnish forest reindeer (R. t. fennicus) likely evolved from Cervus [Rangifer] geuttardi Desmarest, 1822, a reindeer that adapted to forest habitats in Eastern Europe as forests expanded during an interglacial period before the LGM (the Würmian or Weichsel glaciation);. The fossil species geuttardi was later replaced by R. constantini, which was adapted for grasslands, in a second immigration 19,000–20,000 years ago when the LGM turned its forest habitats into tundra, while fennicus survived in isolation in southwestern Europe. R. constantini was then replaced by modern tundra/barren-ground caribou adapted to extreme cold, probably in Beringia, before dispersing west (R. t. tarandus in the Scandinavian mountains and R. t. sibiricus across Siberia) and east (R. t. arcticus in the North American Barrenlands) when rising seas isolated them. Likewise in North America, DNA analysis shows that woodland caribou (R. caribou) diverged from primitive ancestors of tundra/barren-ground caribou not during the LGM, 26,000–19,000 years ago, as previously assumed, but in the Middle Pleistocene around 357,000 years ago. At that time, modern tundra caribou had not even evolved. Woodland caribou are likely more related to extinct North American forest caribou than to barren-ground caribou. For example, the extinct caribou Torontoceros [Rangifer] hypogaeus, had features (robust and short pedicles, smooth antler surface, and high position of second tine) that relate it to forest caribou.

 

Humans started hunting reindeer in both the Mesolithic and Neolithic Periods, and humans are today the main predator in many areas. Norway and Greenland have unbroken traditions of hunting wild reindeer from the Last Glacial Period until the present day. In the non-forested mountains of central Norway, such as Jotunheimen, it is still possible to find remains of stone-built trapping pits, guiding fences and bow rests, built especially for hunting reindeer. These can, with some certainty, be dated to the Migration Period, although it is not unlikely that they have been in use since the Stone Age.

 

Cave paintings by ancient Europeans include both tundra and forest types of reindeer.

 

A 2022 study of ancient environmental DNA from the Early Pleistocene (2 million years ago) Kap Kobenhavn Formation of northern Greenland identified preserved DNA fragments of Rangifer, identified as basal but potentially ancestral to modern reindeer. This suggests that reindeer have inhabited Greenland since at least the Early Pleistocene. Around this time, northern Greenland was 11–19 °C warmer than the Holocene, with a boreal forest hosting a species assemblage with no modern analogue. These are among the oldest DNA fragments ever sequenced.

 

Taxonomy

Carl Linnaeus in 1758 named the Eurasian tundra species Cervus tarandus, the genus Rangifer being credited to Smith, 1827.

 

Rangifer has had a convoluted history because of the similarity in antler architecture (brow tines asymmetrical and often palmate, bez tines, a back tine sometimes branched, and branched at the distal end, often palmate). Because of individual variability, early taxonomists were unable to discern consistent patterns among populations, nor could they, examining collections in Europe, appreciate the difference in habitats and the differing function they imposed on antler architecture. For example, woodland caribou males, rutting in boreal forest where only a few females can be found, collect harems and defend them against other males, for which they have short, straight, strong, much-branched antlers, beams flattened in cross-section, designed for combat — and not too large, so as not to impede them in forested winter ranges. By contrast, modern tundra caribou (see Evolution above) have synchronized calving as a predator-avoidance strategy, which requires large rutting aggregations. Males cannot defend a harem because, while he was busy fighting, they would disappear into the mass of the herd. Males therefore tend individual females; their fights are infrequent and brief. Their antlers are thin, beams round in cross-section, sweep back and then forward with a cluster of branches at the top; these are designed more for visual stimulation of the females. Their bez tines are set low, just above the brow tine, which is vertically flattened to protect the eyes while the buck "threshes" low brush, a courtship display. The low bez tines help the wide flat brow tines dig craters in the hard-packed tundra snow for forage, for which reason brow tines are often called "shovels" in North America and "ice tines" in Europe. The differences in antler architecture reflect fundamental differences in ecology and behavior, and in turn deep divisions in ancestry that were not apparent to the early taxonomists.

 

Similarly, working on museum collections where skins were often faded and in poor states of preservation, early taxonomists could not readily perceive differences in coat patterns that are consistent within a subspecies, but variable among them. Geist calls these "nuptial" characteristics: sexually selected characters that are highly conserved and diagnostic among subspecies.

 

Towards the end of the 19th century, national museums began sending out biological exploration expeditions and collections accumulated. Taxonomists, usually working for the museums began naming subspecies more rigorously, based on statistical differences in detailed cranial, dental and skeletal measurements than antlers and pelage, supplemented by better knowledge of differences in ecology and behavior. From 1898 to 1937, mammalogists named 12 new species (other than barren-ground and woodland, which had been named earlier) of caribou in Canada and Alaska, and three new species and nine new subspecies in Eurasia, each properly described according to the evolving rules of zoological nomenclature, with type localities designated and type specimens deposited in museums.

 

In the mid-20th century, as definitions of "species" evolved, mammalogists in Europe and North America made all Rangifer species conspecific with R. tarandus, and synonymized most of the subspecies. Banfield's often-cited A Revision of the Reindeer and Caribou, Genus Rangifer (1961), eliminated R. t. caboti (the Labrador caribou), R. t. osborni (Osborn's caribou — from British Columbia) and R. t. terranovae (the Newfoundland caribou) as invalid and included only barren-ground caribou, renamed as R. t. groenlandicus (formerly R. arcticus) and woodland caribou as R. t. caribou. However, Banfield made multiple errors, eliciting a scathing review by Ian McTaggart-Cowan in 1962 Most authorities continued to consider all or most subspecies valid; some were quite distinct. In his chapter in the authoritative 2005 reference work Mammal Species of the World, referenced by the American Society of Mammalogists, English zoologist Peter Grubb agreed with Valerius Geist, a specialist on large mammals, that these subspecies were valid (i.e., before the recent revision): In North America, R. t. caboti, R. t. caribou, R. t. dawsoni, R. t. groenlandicus, R. t. osborni, R. t. pearyi, and R. t. terranovae; and in Eurasia, R. t. tarandus, R. t. buskensis (called R. t. valentinae in Europe; see below), R. t. phylarchus, R. t. pearsoni, R. t. sibiricus and R. t. platyrhynchus. These subspecies were retained in the 2011 replacement work Handbook of Mammals of the World Vol. 2: Hoofed Mammals.[8] Most Russian authors also recognized R. t. angustirostris, a forest reindeer from east of Lake Baikal.

 

However, since 1991, many genetic studies have revealed deep divergence between modern tundra reindeer and woodland caribou. Geist (2007) and others continued arguing that the woodland caribou was incorrectly classified, noting that "true woodland caribou, the uniformly dark, small-maned type with the frontally emphasized, flat-beamed antlers", is "scattered thinly along the southern rim of North American caribou distribution". He affirms that the "true woodland caribou is very rare, in very great difficulties and requires the most urgent of attention."

 

In 2011, noting that the former classifications of Rangifer tarandus, either with prevailing taxonomy on subspecies, designations based on ecotypes, or natural population groupings, failed to capture "the variability of caribou across their range in Canada" needed for effective subspecies conservation and management, COSEWIC developed Designatable Unit (DU) attribution, an adaptation of "evolutionary significant units". The 12 designatable units for caribou in Canada (that is, excluding Alaska and Greenland) based on ecology, behavior and, importantly, genetics (but excluding morphology and archaeology) essentially followed the previously-named subspecies distributions, without naming them as such, plus some ecotypes. Ecotypes are not phylogenetically based and cannot substitute for taxonomy.

 

Meanwhile, genetic data continued to accumulate, revealing sufficiently deep divisions to easily separate Rangifer back into six previously named species and to resurrect several previously named subspecies. Molecular data showed that the Greenland caribou (R. t. groenlandicus) and the Svalbard reindeer (R. t. platyrhynchus), although not closely related to each other, were the most genetically divergent among Rangifer clades; that modern (see Evolution above) Eurasian tundra reindeer (R. t. tarandus and R. t. sibiricus) and North American barren-ground caribou (R. t. arcticus), although sharing ancestry, were separable at the subspecies level; that Finnish forest reindeer (R. t. fennicus) clustered well apart from both wild and domestic tundra reindeer and that boreal woodland caribou (R. t. caribou) were separable from all others. Meanwhile, archaeological evidence was accumulating that Eurasian forest reindeer descended from an extinct forest-adapted reindeer and not from tundra reindeer; since they do not share a direct common ancestor, they cannot be conspecific. Similarly, woodland caribou diverged from the ancestors of Arctic caribou before modern barren-ground caribou had evolved, and were more likely related to extinct North American forest reindeer. Lacking a direct shared ancestor, barren-ground and woodland caribou cannot be conspecific.

 

Molecular data also revealed that the four western Canadian montane ecotypes are not woodland caribou: they share a common ancestor with modern barren-ground caribou/tundra reindeer, but distantly, having diverged > 60,000 years ago — before the modern ecotypes had evolved their cold- and darkness-adapted physiologies and mass-migration and aggregation behaviors (see Evolution above). Before Banfield (1961), taxonomists using cranial, dental and skeletal measurements had unequivocally allied these western montane ecotypes with barren-ground caribou, naming them (as in Osgood 1909[85] Murie, 1935 and Anderson 1946, among others) R. t. stonei, R. t. montanus, R. t. fortidens and R. t. osborni, respectively, and this phylogeny was confirmed by genetic analysis.

 

DNA also revealed three unnamed clades that, based on genetic distance, genetic divergence and shared vs. private haplotypes and alleles, together with ecological and behavioral differences, may justify separation at the subspecies level: the Atlantic-Gaspésie caribou (COSEWIC DU11), an eastern montane ecotype of the boreal woodland caribou, and the Baffin Island caribou. Neither one of these clades has yet been formally described or named.

 

Jenkins et al. (2012) said that "[Baffin Island] caribou are unique compared to other Barrenground herds, as they do not overwinter in forested habitat, nor do all caribou undertake long seasonal migrations to calving areas." It also shares a mtDNA haplotype with Labrador caribou, in the North American lineage (i.e., woodland caribou). Røed et al. (1991) had noted:

 

Among Baffin Island caribou the TFL2 allele was the most common allele (p=0.521), while this allele was absent, or present in very low frequencies, in other caribou populations , including the Canadian barren-ground caribou from the Beverly herd. A large genetic difference between Baffin Island caribou and the Beverly herd was also indicated by eight alleles found in the Beverly herd which were absent from the Baffin Island samples.

 

Jenkins et al. (2018) also reported genetic distinctiveness of Baffin Island caribou from all other barren-ground caribou; its genetic signature was not found on the mainland or on other islands; nor were Beverly herd (the nearest mainly barren-ground caribou) alleles present in Baffin Island caribou, evidence of reproductive isolation.

 

These advances in Rangifer genetics were brought together with previous morphological-based descriptions, ecology, behavior and archaeology to propose a new revision of the genus.

 

The scientific name Tarandus rangifer buskensis Millais, 1915 (the Busk Mountains reindeer) was selected as the senior synonym to R. t. valentinae Flerov, 1933, in Mammal Species of the World but Russian authors do not recognize Millais and Millais' articles in a hunting travelogue, The Gun at Home and Abroad, seem short of a taxonomic authority.

 

The scientific name groenlandicus is fraught with problems. Edwards (1743) illustrated and claimed to have seen a male specimen (“head of perfect horns...”) from Greenland and said that a Captain Craycott had brought a live pair from Greenland to England in 1738. He named it Capra groenlandicus, Greenland reindeer. Linnaeus, in the 12th edition of Systema naturae, gave grœnlandicus as a synonym for Cervus tarandus. Borowski disagreed (and again changed the spelling), saying Cervus grönlandicus was morphologically distinct from Eurasian tundra reindeer. Baird placed it under the genus Rangifer as R. grœnlandicus. It went back and forth as a full species or subspecies of the barren-ground caribou (R. arcticus) or a subspecies of the tundra reindeer (R. tarandus), but always as the Greenland reindeer/caribou. Taxonomists consistently documented morphological differences between Greenland and other caribou/reindeer in cranial measurements, dentition, antler architecture, etc. Then Banfield (1961) in his famously flawed revision, gave the name groenlandicus to all the barren-ground caribou in North America, Greenland included, because groenlandicus pre-dates Richardson’s R. arctus,. However, because genetic data shows the Greenland caribou to be the most distantly related of any caribou to all the others (genetic distance, FST = 44%, whereas most cervid (deer family) species have a genetic distance of 2% to 5%)--as well as behavioral and morphological differences—a recent revision returned it to species status as R. groenlandicus. Although it has been assumed that the larger caribou that appeared in Greenland 4,000 years ago originated from Baffin Island (itself unique; see Taxonomy above), a reconstruction of LGM glacial retreat and caribou advance (Yannic et al. 2013) shows colonization by NAL lineage caribou more likely. Their PCA and tree diagrams show Greenland caribou clustering outside of the Beringian-Eurasian lineage.

 

The scientific name R. t. granti has a very interesting history. Allen (1902) named it as a distinct species, R. granti, from the "western end of Alaska Peninsula, opposite Popoff Island" and noting that:

 

Rangifer granti is a representative of the Barren Ground group of Caribou, which includes R. arcticus of the Arctic Coast and R. granlandicus of Greenland. It is not closely related to R. stonei of the Kenai Peninsula, from which it differs not only in its very much smaller size, but in important cranial characters and in coloration. ...The external and cranial differences between R. granti and the various forms of the Woodland Caribou are so great in almost every respect that no detailed comparison is necessary. ...According to Mr. Stone, Rangifer granti inhabits the " barren land of Alaska Peninsula, ranging well up into the mountains in summer, but descending to the lower levels in winter, generally feeding on the low flat lands near the coast and in the foothills...As regards cranial characters no comparison is necessary with R. montanus or with any of the woodland forms."

 

Osgood and Murie (1935), agreeing with granti's close relationship with the barren-ground caribou, brought it under R. arcticus as a subspecies, R. t. granti. Anderson (1946) and Banfield (1961), based on statistical analysis of cranial, dental and other characters, agreed. But Banfield (1961) also synonymized Alaska's large R. stonei with other mountain caribou of British Columbia and the Yukon as invalid subspecies of woodland caribou, then R. t. caribou. This left the small, migratory barren-ground caribou of Alaska and the Yukon, including the Porcupine caribou herd, without a name, which Banfield rectified in his 1974 Mammals of Canada by extending to them the name "granti". The late Valerius Geist (1998), in the only error in his whole illustrious career, re-analyzed Banfield's data with additional specimens found in an unpublished report he cites as "Skal, 1982", but was "not able to find diagnostic features that could segregate this form from the western barren ground type." But Skal 1982 had included specimens from the eastern end of the Alaska Peninsula and the Kenai Peninsula, the range of the larger Stone's caribou. Later, geneticists comparing barren-ground caribou of Alaska with those of mainland Canada found little difference and they all became the former R. t. groenlandicus (now R. t. arcticus). R. t. granti was lost in the oblivion of invalid taxonomy until Alaskan researchers sampled some small, pale caribou from the western end of the Alaska Peninsula, their range enclosing the type locality designated by Allen (1902) and found them to be genetically distinct from all other caribou in Alaska. Thus, granti was rediscovered, its range restricted to that originally described.

 

Stone's caribou (R. t. stonei), a large montane type, was described from the Kenai Peninsula (where, apparently, it was never common except in years of great abundance), the eastern end of the Alaska Peninsula, and mountains throughout southern and eastern Alaska. It was placed under R. arcticus as a subspecies, R. t. stonei, and later synonymised as noted above. The same genetic analyses mentioned above for R. t. granti resulted in resurrecting R. t. stonei as well.

 

The Sakhalin reindeer (R. t. setoni), endemic to Sakhalin, was described as Rangifer tarandus setoni Flerov, 1933, but Banfield (1961) brought it under R. t. fennicus as a junior synonym. The wild reindeer on the island are apparently extinct, having been replaced by domestic reindeer.

 

Some of the Rangifer species and subspecies may be further divided by ecotype depending on several behavioral factors – predominant habitat use (northern, tundra, mountain, forest, boreal forest, forest-dwelling, woodland, woodland (boreal), woodland (migratory) or woodland (mountain), spacing (dispersed or aggregated) and migration patterns (sedentary or migratory). North American examples of this are the Torngat Mountain population DU10, an ecotype of R. t. caboti; a recently discovered and unnamed clade between the Mackenzie River and Great Bear Lake of Beringian-Eurasian lineage, an ecotype of R. t. osborni; the Atlantic-Gaspésie population DU11, an eastern montane ecotype of the boreal woodland caribou (R. t. caribou); the Baffin Island caribou, an ecotype of the barren-ground caribou (R. t. arcticus); and the Dolphin-Union “herd”, another ecotype of R. t. arcticus. The last three of these likely qualify as subspecies, but they have not yet been formally described or named.

 

Physical characteristics

Naming in this and following sections follows the taxonomy in the authoritative 2011 reference work Handbook of Mammals of the World Vol. 2: Hoofed Mammals.

 

Antlers

In most cervid species, only males grow antlers; the reindeer is the only cervid species in which females also grow them normally. Androgens play an essential role in the antler formation of cervids. The antlerogenic genes in reindeer have more sensitivity to androgens in comparison with other cervids.

 

There is considerable variation among species and subspecies in the size of the antlers (e.g., they are rather small and spindly in the northernmost species and subspecies), but on average the bull's antlers are the second largest of any extant deer, after those of the male moose. In the largest subspecies, the antlers of large bulls can range up to 100 cm (39 in) in width and 135 cm (53 in) in beam length. They have the largest antlers relative to body size among living deer species.[116] Antler size measured in number of points reflects the nutritional status of the reindeer and climate variation of its environment. The number of points on male reindeer increases from birth to 5 years of age and remains relatively constant from then on.  "In male caribou, antler mass (but not the number of tines) varies in concert with body mass." While antlers of male woodland caribou are typically smaller than those of male barren-ground caribou, they can be over 1 m (3 ft 3 in) across. They are flattened in cross-section, compact and relatively dense.[36] Geist describes them as frontally emphasized, flat-beamed antlers. Woodland caribou antlers are thicker and broader than those of the barren-ground caribou and their legs and heads are longer. Quebec-Labrador male caribou antlers can be significantly larger and wider than other woodland caribou. Central barren-ground male caribou antlers are perhaps the most diverse in configuration and can grow to be very high and wide. Osborn's caribou antlers are typically the most massive, with the largest circumference measurements.

 

The antlers' main beams begin at the brow "extending posterior over the shoulders and bowing so that the tips point forward. The prominent, palmate brow tines extend forward, over the face." The antlers typically have two separate groups of points, lower and upper.

 

Antlers begin to grow on male reindeer in March or April and on female reindeer in May or June. This process is called antlerogenesis. Antlers grow very quickly every year on the bulls. As the antlers grow, they are covered in thick velvet, filled with blood vessels and spongy in texture. The antler velvet of the barren-ground caribou and the boreal woodland caribou is dark chocolate brown. The velvet that covers growing antlers is a highly vascularised skin. This velvet is dark brown on woodland or barren-ground caribou and slate-grey on Peary caribou and the Dolphin-Union caribou herd. Velvet lumps in March can develop into a rack measuring more than a meter in length (3 ft) by August.

  

A R. tarandus skull

When the antler growth is fully grown and hardened, the velvet is shed or rubbed off. To the Inuit, for whom the caribou is a "culturally important keystone species", the months are named after landmarks in the caribou life cycle. For example, amiraijaut in the Igloolik region is "when velvet falls off caribou antlers."

 

Male reindeer use their antlers to compete with other males during the mating season. Butler (1986) showed that the social requirements of caribou females during the rut determines the mating strategies of males and, consequently, the form of male antlers. In describing woodland caribou, which have a harem-defense mating system, SARA wrote, "During the rut, males engage in frequent and furious sparring battles with their antlers. Large males with large antlers do most of the mating." Reindeer continue to migrate until the bulls have spent their back fat. By contrast, barren-ground caribou males tend individual females and their fights are brief and much less intense; consequently, their antlers are long, and thin, round in cross-section and less branched and are designed more for show (or sexual attraction) than fighting.

 

In late autumn or early winter after the rut, male reindeer lose their antlers, growing a new pair the next summer with a larger rack than the previous year. Female reindeer keep their antlers until they calve. In the Scandinavian and Arctic Circle populations, old bulls' antlers fall off in late December, young bulls' antlers fall off in the early spring, and cows' antlers fall off in the summer.

 

When male reindeer shed their antlers in early to mid-winter, the antlered cows acquire the highest ranks in the feeding hierarchy, gaining access to the best forage areas. These cows are healthier than those without antlers. Calves whose mothers do not have antlers are more prone to disease and have a significantly higher mortality. Cows in good nutritional condition, for example, during a mild winter with good winter range quality, may grow new antlers earlier as antler growth requires high intake.

  

A R. t. platyrhynchus skull

According to a respected Igloolik elder, Noah Piugaattuk, who was one of the last outpost camp leaders, caribou (tuktu) antlers

 

...get detached every year...Young males lose the velvet from the antlers much more quickly than female caribou even though they are not fully mature. They start to work with their antlers just as soon as the velvet starts to fall off. The young males engage in fights with their antlers towards autumn...soon after the velvet had fallen off they will be red, as they start to get bleached their colour changes...When the velvet starts to fall off the antler is red because the antler is made from blood. The antler is the blood that has hardened; in fact, the core of the antler is still bloody when the velvet starts to fall off, at least close to the base.

 

— Elder Noah Piugaattuk of Igloolik cited in "Tuktu — Caribou" (2002) "Canada's Polar Life"

According to the Igloolik Oral History Project (IOHP), "Caribou antlers provided the Inuit with a myriad of implements, from snow knives and shovels to drying racks and seal-hunting tools. A complex set of terms describes each part of the antler and relates it to its various uses". Currently, the larger racks of antlers are used by Inuit as materials for carving. Iqaluit-based Jackoposie Oopakak's 1989 carving, entitled Nunali, which means "place where people live", and which is part of the permanent collection of the National Gallery of Canada, includes a massive set of caribou antlers on which he has intricately carved the miniaturized world of the Inuit where "Arctic birds, caribou, polar bears, seals, and whales are interspersed with human activities of fishing, hunting, cleaning skins, stretching boots, and travelling by dog sled and kayak...from the base of the antlers to the tip of each branch".

 

Pelt

The color of the fur varies considerably, both between individuals and depending on season and species. Northern populations, which usually are relatively small, are whiter, while southern populations, which typically are relatively large, are darker. This can be seen well in North America, where the northernmost subspecies, the Peary caribou, is the whitest and smallest subspecies of the continent, while the Selkirk Mountains caribou (Southern Mountain population DU9) is the darkest and nearly the largest, only exceeded in size by Osborn's caribou (Northern Mountain population DU7).

 

The coat has two layers of fur: a dense woolly undercoat and a longer-haired overcoat consisting of hollow, air-filled hairs. Fur is the primary insulation factor that allows reindeer to regulate their core body temperature in relation to their environment, the thermogradient, even if the temperature rises to 38 °C (100 °F). In 1913, Dugmore noted how the woodland caribou swim so high out of the water, unlike any other mammal, because their hollow, "air-filled, quill-like hair" acts as a supporting "life jacket".

 

A darker belly color may be caused by two mutations of MC1R. They appear to be more common in domestic reindeer herds.

 

Heat exchange

Blood moving into the legs is cooled by blood returning to the body in a countercurrent heat exchange (CCHE), a highly efficient means of minimizing heat loss through the skin's surface. In the CCHE mechanism, in cold weather, blood vessels are closely knotted and intertwined with arteries to the skin and appendages that carry warm blood with veins returning to the body that carry cold blood causing the warm arterial blood to exchange heat with the cold venous blood. In this way, their legs for example are kept cool, maintaining the core body temperature nearly 30 °C (54 °F) higher with less heat lost to the environment. Heat is thus recycled instead of being dissipated. The "heart does not have to pump blood as rapidly in order to maintain a constant body core temperature and thus, metabolic rate." CCHE is present in animals like reindeer, fox and moose living in extreme conditions of cold or hot weather as a mechanism for retaining the heat in (or out of) the body. These are countercurrent exchange systems with the same fluid, usually blood, in a circuit, used for both directions of flow.

 

Reindeer have specialized counter-current vascular heat exchange in their nasal passages. Temperature gradient along the nasal mucosa is under physiological control. Incoming cold air is warmed by body heat before entering the lungs and water is condensed from the expired air and captured before the reindeer's breath is exhaled, then used to moisten dry incoming air and possibly be absorbed into the blood through the mucous membranes. Like moose, caribou have specialized noses featuring nasal turbinate bones that dramatically increase the surface area within the nostrils.

 

Hooves

The reindeer has large feet with crescent-shaped cloven hooves for walking in snow or swamps. According to the Species at Risk Public Registry (SARA), woodland

 

"Caribou have large feet with four toes. In addition to two small ones, called "dew claws," they have two large, crescent-shaped toes that support most of their weight and serve as shovels when digging for food under snow. These large concave hooves offer stable support on wet, soggy ground and on crusty snow. The pads of the hoof change from a thick, fleshy shape in the summer to become hard and thin in the winter months, reducing the animal's exposure to the cold ground. Additional winter protection comes from the long hair between the "toes"; it covers the pads so the caribou walks only on the horny rim of the hooves."

 

— SARA 2014

Reindeer hooves adapt to the season: in the summer, when the tundra is soft and wet, the footpads become sponge-like and provide extra traction. In the winter, the pads shrink and tighten, exposing the rim of the hoof, which cuts into the ice and crusted snow to keep it from slipping. This also enables them to dig down (an activity known as "cratering") through the snow to their favourite food, a lichen known as reindeer lichen (Cladonia rangiferina).

 

Size

The females (or "cows" as they are often called) usually measure 162–205 cm (64–81 in) in length and weigh 80–120 kg (180–260 lb). The males (or "bulls" as they are often called) are typically larger (to an extent which varies between the different species and subspecies), measuring 180–214 cm (71–84 in) in length and usually weighing 159–182 kg (351–401 lb). Exceptionally large bulls have weighed as much as 318 kg (701 lb). Weight varies drastically between the seasons, with bulls losing as much as 40% of their pre-rut weight.

 

The shoulder height is usually 85 to 150 cm (33 to 59 in), and the tail is 14 to 20 cm (5.5 to 7.9 in) long.

 

The reindeer from Svalbard are the smallest of all. They are also relatively short-legged and may have a shoulder height of as little as 80 cm (31 in), thereby following Allen's rule.

 

Clicking sound

The knees of many species and subspecies of reindeer are adapted to produce a clicking sound as they walk. The sounds originate in the tendons of the knees and may be audible from several hundred meters away. The frequency of the knee-clicks is one of a range of signals that establish relative positions on a dominance scale among reindeer. "Specifically, loud knee-clicking is discovered to be an honest signal of body size, providing an exceptional example of the potential for non-vocal acoustic communication in mammals." The clicking sound made by reindeer as they walk is caused by small tendons slipping over bone protuberances (sesamoid bones) in their feet. The sound is made when a reindeer is walking or running, occurring when the full weight of the foot is on the ground or just after it is relieved of the weight.

 

Eyes

A study by researchers from University College London in 2011 revealed that reindeer can see light with wavelengths as short as 320 nm (i.e. in the ultraviolet range), considerably below the human threshold of 400 nm. It is thought that this ability helps them to survive in the Arctic, because many objects that blend into the landscape in light visible to humans, such as urine and fur, produce sharp contrasts in ultraviolet. It has been proposed that UV flashes on power lines are responsible for reindeer avoiding power lines because "...in darkness these animals see power lines not as dim, passive structures but, rather, as lines of flickering light stretching across the terrain."

 

In 2023, researchers studying reindeer living in Cairngorms National Park, Scotland, suggested that UV visual sensitivity in reindeer helps them detect UV-absorbing lichens against a background of UV-reflecting snows.

 

The tapetum lucidum of Arctic reindeer eyes changes in color from gold in summer to blue in winter to improve their vision during times of continuous darkness, and perhaps enable them to better spot predators.

 

Biology and behaviors

Reindeer have developed adaptations for optimal metabolic efficiency during warm months as well as for during cold months. The body composition of reindeer varies highly with the seasons. Of particular interest is the body composition and diet of breeding and non-breeding females between the seasons. Breeding females have more body mass than non-breeding females between the months of March and September with a difference of around 10 kg (22 lb) more than non-breeding females. From November to December, non-breeding females have more body mass than breeding females, as non-breeding females are able to focus their energies towards storage during colder months rather than lactation and reproduction. Body masses of both breeding and non-breeding females peaks in September. During the months of March through April, breeding females have more fat mass than the non-breeding females with a difference of almost 3 kg (6.6 lb). After this, however, non-breeding females on average have a higher body fat mass than do breeding females.

 

The environmental variations play a large part in reindeer nutrition, as winter nutrition is crucial to adult and neonatal survival rates. Lichens are a staple during the winter months as they are a readily available food source, which reduces the reliance on stored body reserves. Lichens are a crucial part of the reindeer diet; however, they are less prevalent in the diet of pregnant reindeer compared to non-pregnant individuals. The amount of lichen in a diet is found more in non-pregnant adult diets than pregnant individuals due to the lack of nutritional value. Although lichens are high in carbohydrates, they are lacking in essential proteins that vascular plants provide. The amount of lichen in a diet decreases in latitude, which results in nutritional stress being higher in areas with low lichen abundance. 

 

In a study of seasonal light-dark cycles on sleep patterns of female reindeer, researchers performed non-invasive electroencephalography (EEG) on reindeer kept in a stable at the UiT The Arctic University of Norway. The EEG recordings showed that: the more time reindeer spend ruminating, the less time they spend in non-rapid eye movement sleep (NREM sleep); and reindeer's brainwaves during rumination resemble the brainwaves present during NREM sleep. These results suggest that, by reducing the time requirement for NREM sleep, reindeer are able to spend more time feeding during the summer months, when food is abundant.

 

Reproduction and life cycle

Reindeer mate in late September to early November, and the gestation period is about 228–234 days. During the mating season, bulls battle for access to cows. Two bulls will lock each other's antlers together and try to push each other away. The most dominant bulls can collect as many as 15–20 cows to mate with. A bull will stop eating during this time and lose much of his body fat reserves.

 

To calve, "females travel to isolated, relatively predator-free areas such as islands in lakes, peatlands, lake-shores, or tundra." As females select the habitat for the birth of their calves, they are warier than males. Dugmore noted that, in their seasonal migrations, the herd follows a female for that reason. Newborns weigh on average 6 kg (13 lb).[148] In May or June, the calves are born. After 45 days, the calves are able to graze and forage, but continue suckling until the following autumn when they become independent from their mothers.

 

Bulls live four years less than the cows, whose maximum longevity is about 17 years. Cows with a normal body size and who have had sufficient summer nutrition can begin breeding anytime between the ages of 1 and 3 years. When a cow has undergone nutritional stress, it is possible for her to not reproduce for the year. Dominant bulls, those with larger body size and antler racks, inseminate more than one cow a season.

 

Social structure, migration and range

Some populations of North American caribou; for example, many herds in the barren-ground caribou subspecies and some woodland caribou in Ungava and northern Labrador, migrate the farthest of any terrestrial mammal, traveling up to 5,000 km (3,000 mi) a year, and covering 1,000,000 km2 (400,000 sq mi). Other North American populations, the boreal woodland caribou for example, are largely sedentary. The European populations are known to have shorter migrations. Island populations, such as the Novaya Zemlya and Svalbard reindeer and the Peary caribou, make local movements both within and among islands. Migrating reindeer can be negatively affected by parasite loads. Severely infected individuals are weak and probably have shortened lifespans, but parasite levels vary between populations. Infections create an effect known as culling: infected migrating animals are less likely to complete the migration.

 

Normally travelling about 19–55 km (12–34 mi) a day while migrating, the caribou can run at speeds of 60–80 km/h (37–50 mph).[2] Young calves can already outrun an Olympic sprinter when only 1 day old. During the spring migration, smaller herds will group together to form larger herds of 50,000 to 500,000 animals, but during autumn migrations, the groups become smaller and the reindeer begin to mate. During winter, reindeer travel to forested areas to forage under the snow. By spring, groups leave their winter grounds to go to the calving grounds. A reindeer can swim easily and quickly, normally at about 6.5 km/h (4.0 mph) but, if necessary, at 10 km/h (6.2 mph) and migrating herds will not hesitate to swim across a large lake or broad river.

 

The barren-ground caribou form large herds and undertake lengthy seasonal migrations from winter feeding grounds in taiga to spring calving grounds and summer range in the tundra. The migrations of the Porcupine herd of barren-ground caribou are among the longest of any mammal. Greenland caribou, found in southwestern Greenland, are "mixed migrators" and many individuals do not migrate; those that do migrate less than 60 km. Unlike the individual-tending mating system, aggregated rutting, synchronized calving and aggregated post-calving of barren-ground caribou, Greenland caribou have a harem-defense mating system and dispersed calving and they do not aggregate.

 

Although most wild tundra reindeer migrate between their winter range in taiga and summer range in tundra, some ecotypes or herds are more or less sedentary. Novaya Zemlya reindeer (R. t. pearsoni) formerly wintered on the mainland and migrated across the ice to the islands for summer, but only a few now migrate. Finnish forest reindeer (R. t. fennicus) were formerly distributed in most of the coniferous forest zones south of the tree line, including some mountains, but are now spottily distributed within this zone.

 

As an adaptation to their Arctic environment, they have lost their circadian rhythm.

 

Distribution and habitat

Originally, the reindeer was found in Scandinavia, Eastern Europe, Greenland, Russia, Mongolia and northern China north of the 50th latitude. In North America, it was found in Canada, Alaska, and the northern contiguous United States from Maine to Washington. In the 19th century, it was still present in southern Idaho. Even in historical times, it probably occurred naturally in Ireland, and it is believed to have lived in Scotland until the 12th century, when the last reindeer were hunted in Orkney. During the Late Pleistocene Epoch, reindeer occurred further south in North America, such as in Nevada, Tennessee, and Alabama, and as far south as Spain in Europe Today, wild reindeer have disappeared from these areas, especially from the southern parts, where it vanished almost everywhere. Large populations of wild reindeer are still found in Norway, Finland, Siberia, Greenland, Alaska and Canada.

 

According to Grubb (2005), Rangifer is "circumboreal in the tundra and taiga" from "Svalbard, Norway, Finland, Russia, Alaska (USA) and Canada including most Arctic islands, and Greenland, south to northern Mongolia, China (Inner Mongolia), Sakhalin Island, and USA (northern Idaho and Great Lakes region)." Reindeer were introduced to, and are feral in, "Iceland, Kerguelen Islands, South Georgia Island, Pribilof Islands, St. Matthew Island": a free-ranging semi-domesticated herd is also present in Scotland.

 

There is strong regional variation in Rangifer herd size. There are large population differences among individual herds and the size of individual herds has varied greatly since 1970. The largest of all herds (in Taimyr, Russia) has varied between 400,000 and 1,000,000; the second largest herd (at the George River in Canada) has varied between 28,000 and 385,000.

 

While Rangifer is a widespread and numerous genus in the northern Holarctic, being present in both tundra and taiga (boreal forest), by 2013, many herds had "unusually low numbers" and their winter ranges in particular were smaller than they used to be. Caribou and reindeer numbers have fluctuated historically, but many herds are in decline across their range. This global decline is linked to climate change for northern migratory herds and industrial disturbance of habitat for non-migratory herds. Barren-ground caribou are susceptible to the effects of climate change due to a mismatch in the phenological process between the availability of food during the calving period.

 

In November 2016, it was reported that more than 81,000 reindeer in Russia had died as a result of climate change. Longer autumns, leading to increased amounts of freezing rain, created a few inches of ice over lichen, causing many reindeer to starve to death.

 

Diet.

Reindeer are ruminants, having a four-chambered stomach. They mainly eat lichens in winter, especially reindeer lichen (Cladonia rangiferina); they are the only large mammal able to metabolize lichen owing to specialised bacteria and protozoa in their gut. They are also the only animals (except for some gastropods) in which the enzyme lichenase, which breaks down lichenin to glucose, has been found. However, they also eat the leaves of willows and birches, as well as sedges and grasses.

 

Reindeer are osteophagous; they are known to gnaw and partly consume shed antlers as a dietary supplement and in some extreme cases will cannibalise each other's antlers before shedding. There is also some evidence to suggest that on occasion, especially in the spring when they are nutritionally stressed, they will feed on small rodents (such as lemmings), fish (such as the Arctic char (Salvelinus alpinus)), and bird eggs. Reindeer herded by the Chukchis have been known to devour mushrooms enthusiastically in late summer.

 

During the Arctic summer, when there is continuous daylight, reindeer change their sleeping pattern from one synchronised with the sun to an ultradian pattern, in which they sleep when they need to digest food.

 

Predators.

A variety of predators prey heavily on reindeer, including overhunting by people in some areas, which contributes to the decline of populations.

 

Golden eagles prey on calves and are the most prolific hunter on the calving grounds. Wolverines will take newborn calves or birthing cows, as well as (less commonly) infirm adults.

 

Brown bears and polar bears prey on reindeer of all ages but, like wolverines, are most likely to attack weaker animals, such as calves and sick reindeer, since healthy adult reindeer can usually outpace a bear. The gray wolf is the most effective natural predator of adult reindeer and sometimes takes large numbers, especially during the winter. Some gray wolf packs, as well as individual grizzly bears in Canada, may follow and live off of a particular reindeer herd year-round.

 

In 2020, scientists on Svalbard witnessed, and were able to film for the first time, a polar bear attack reindeer, driving one into the ocean, where the polar bear caught up with and killed it. The same bear successfully repeated this hunting technique the next day. On Svalbard, reindeer remains account for 27.3% in polar bear scats, suggesting that they "may be a significant part of the polar bear's diet in that area".

 

Additionally, as carrion, reindeer may be scavenged opportunistically by red and Arctic foxes, various species of eagles, hawks and falcons, and common ravens.

 

Bloodsucking insects, such as mosquitoes, black flies, and especially the reindeer warble fly or reindeer botfly (Hypoderma tarandi) and the reindeer nose botfly (Cephenemyia trompe), are a plague to reindeer during the summer and can cause enough stress to inhibit feeding and calving behaviors. An adult reindeer will lose perhaps about 1 L (0.22 imp gal; 0.26 US gal) of blood to biting insects for every week it spends in the tundra. The population numbers of some of these predators is influenced by the migration of reindeer. Tormenting insects keep caribou on the move, searching for windy areas like hilltops and mountain ridges, rock reefs, lakeshore and forest openings, or snow patches that offer respite from the buzzing horde. Gathering in large herds is another strategy that caribou use to block insects.

 

Reindeer are good swimmers and, in one case, the entire body of a reindeer was found in the stomach of a Greenland shark (Somniosus microcephalus), a species found in the far North Atlantic.

 

Other threats

White-tailed deer (Odocoileus virginianus) commonly carry meningeal worm or brainworm (Parelaphostrongylus tenuis), a nematode parasite that causes reindeer, moose (Alces alces), elk (Cervus canadensis), and mule deer (Odocoileus hemionus) to develop fatal neurological symptoms which include a loss of fear of humans. White-tailed deer that carry this worm are partially immune to it.

 

Changes in climate and habitat beginning in the 20th century have expanded range overlap between white-tailed deer and caribou, increasing the frequency of infection within the reindeer population. This increase in infection is a concern for wildlife managers. Human activities, such as "clear-cutting forestry practices, forest fires, and the clearing for agriculture, roadways, railways, and power lines," favor the conversion of habitats into the preferred habitat of the white-tailed deer – "open forest interspersed with meadows, clearings, grasslands, and riparian flatlands." Towards the end of the Soviet Union, there was increasingly open admission from the Soviet government that reindeer numbers were being negatively affected by human activity, and that this must be remediated especially by supporting reindeer breeding by native herders.

 

Conservation

Current status

While overall widespread and numerous, some reindeer species and subspecies are rare and three subspecies have already become extinct. As of 2015, the IUCN has classified the reindeer as Vulnerable due to an observed population decline of 40% over the last +25 years. According to IUCN, Rangifer tarandus as a species is not endangered because of its overall large population and its widespread range.

 

In North America, the Queen Charlotte Islands caribou and the East Greenland caribou both became extinct in the early 20th century, the Peary caribou is designated as Endangered, the boreal woodland caribou is designated as Threatened and some individual populations are endangered as well. While the barren-ground caribou is not designated as Threatened, many individual herds — including some of the largest — are declining and there is much concern at the local level. Grant's caribou, a small, pale subspecies endemic to the western end of the Alaska Peninsula and the adjacent islands, has not been assessed as to its conservation status.

 

The status of the Dolphin-Union "herd" was upgraded to Endangered in 2017. In NWT, Dolphin-Union caribou were listed as Special Concern under the NWT Species at Risk (NWT) Act (2013).

 

Both the Selkirk Mountains caribou (Southern Mountain population DU9) and the Rocky Mountain caribou (Central Mountain population DU8) are classified as Endangered in Canada in regions such as southeastern British Columbia at the Canada–United States border, along the Columbia and Kootenay Rivers and around Kootenay Lake. Rocky Mountain caribou are extirpated from Banff National Park, but a small population remains in Jasper National Park and in mountain ranges to the northwest into British Columbia. Montane caribou are now considered extirpated in the contiguous United States, including Washington and Idaho. Osborn's caribou (Northern Mountain population DU7) is classified as Threatened in Canada.

 

In Eurasia, the Sakhalin reindeer is extinct (and has been replaced by domestic reindeer) and reindeer on most of the Novaya Zemlya islands have also been replaced by domestic reindeer, although some wild reindeer still persist on the northern islands. Many Siberian tundra reindeer herds have declined, some dangerously, but the Taymir herd remains strong and in total about 940,000 wild Siberian tundra reindeer were estimated in 2010.

 

There is strong regional variation in Rangifer herd size. By 2013, many caribou herds in North America had "unusually low numbers" and their winter ranges in particular were smaller than they used to be. Caribou numbers have fluctuated historically, but many herds are in decline across their range. There are many factors contributing to the decline in numbers.

 

Boreal woodland caribou

Ongoing human development of their habitat has caused populations of boreal woodland caribou to disappear from their original southern range. In particular, boreal woodland caribou were extirpated in many areas of eastern North America in the beginning of the 20th century.

The reindeer or caribou (Rangifer tarandus) is a species of deer with circumpolar distribution, native to Arctic, subarctic, tundra, boreal, and mountainous regions of Northern Europe, Siberia, and North America. It is the only representative of the genus Rangifer. More recent studies suggest the splitting of reindeer and caribou into six distinct species over their range.

 

Reindeer occur in both migratory and sedentary populations, and their herd sizes vary greatly in different regions. The tundra subspecies are adapted for extreme cold, and some are adapted for long-distance migration.

 

Reindeer vary greatly in size and color from the smallest, the Svalbard reindeer (R. (t.) platyrhynchus), to the largest, Osborn's caribou (R. t. osborni). Although reindeer are quite numerous, some species and subspecies are in decline and considered vulnerable. They are unique among deer (Cervidae) in that females may have antlers, although the prevalence of antlered females varies by species and subspecies.

 

Reindeer are the only successfully semi-domesticated deer on a large scale in the world. Both wild and domestic reindeer have been an important source of food, clothing, and shelter for Arctic people from prehistorical times. They are still herded and hunted today. In some traditional Christmas legends, Santa Claus's reindeer pull a sleigh through the night sky to help Santa Claus deliver gifts to good children on Christmas Eve.

 

Description

Names follow international convention before the recent revision[9] (see Taxonomy below). Reindeer/caribou (Rangifer) vary in size from the smallest, the Svalbard reindeer (R. (t.) platyrhynchus), to the largest, Osborn's caribou (R. t. osborni). They also vary in coat color and antler architecture.

 

The North American range of caribou extends from Alaska through the Yukon, the Northwest Territories and Nunavut throughout the tundra, taiga and boreal forest and south through the Canadian Rocky Mountains. Of the eight subspecies classified by Harding (2022) into the Arctic caribou (R. arcticus), the migratory mainland barren-ground caribou of Arctic Alaska and Canada (R. t. arcticus), summer in tundra and winter in taiga, a transitional forest zone between boreal forest and tundra; the nomadic Peary caribou (R. t. pearyi) lives in the polar desert of the High Arctic Archipelago and Grant's caribou (R. t. granti) lives in the western end of the Alaska Peninsula and the adjacent islands; the other four subspecies, Osborn's caribou (R. t. osborni), Stone's caribou (R. t. stonei), the Rocky Mountain caribou (R. t. fortidens) and the Selkirk Mountains caribou (R. t. montanus) are all montane. The extinct insular Queen Charlotte Islands caribou (R. t. dawsoni), lived on Graham Island in Haida Gwaii (formerly known as the Queen Charlotte Islands).

 

The boreal woodland caribou (R. t. caribou), lives in the boreal forest of northeastern Canada: the Labrador or Ungava caribou of northern Quebec and northern Labrador (R. t. caboti), and the Newfoundland caribou of Newfoundland (R. t. terranovae) have been found to be genetically in the woodland caribou lineage.

 

In Eurasia, both wild and domestic reindeer are distributed across the tundra and into the taiga. Eurasian mountain reindeer (R. t. tarandus) are close to North American caribou genetically and visually, but with sufficient differences to warrant division into two species. The unique, insular Svalbard reindeer inhabits the Svalbard Archipelago. The Finnish forest reindeer (R. t. fennicus) is spottily distributed in the coniferous forest zones from Finland to east of Lake Baikal: the Siberian forest reindeer (R. t. valentinae, formerly called the Busk Mountains reindeer (R. t. buskensis) by American taxonomists) occupies the Altai and Ural Mountains.

 

Male ("bull") and female ("cow") reindeer can grow antlers annually, although the proportion of females that grow antlers varies greatly between populations. Antlers are typically larger on males. Antler architecture varies by species and subspecies and, together with pelage differences, can often be used to distinguish between species and subspecies (see illustrations in Geist, 1991 and Geist, 1998).

 

Status

About 25,000 mountain reindeer (R. t. tarandus) still live in the mountains of Norway, notably in Hardangervidda. In Sweden there are approximately 250,000 reindeer in herds managed by Sami villages. Russia manages 19 herds of Siberian tundra reindeer (R. t. sibiricus) that total about 940,000. The Taimyr herd of Siberian tundra reindeer is the largest wild reindeer herd in the world, varying between 400,000 and 1,000,000; it is a metapopulation consisting of several subpopulations — some of which are phenotypically different — with different migration routes and calving areas. The Kamchatkan reindeer (R. t. phylarchus), a forest subspecies, formerly included reindeer west of the Sea of Okhotsk which, however, are indistinguishable genetically from the Jano-Indigirka, East Siberian taiga and Chukotka populations of R. t. sibiricus. Siberian tundra reindeer herds have been in decline but are stable or increasing since 2000.

 

Insular (island) reindeer, classified as the Novaya Zemlya reindeer (R. t. pearsoni) occupy several island groups: the Novaya Zemlya Archipelago (about 5,000 animals at last count, but most of these are either domestic reindeer or domestic-wild hybrids), the New Siberia Archipelago (about 10,000 to 15,000), and Wrangel Island (200 to 300 feral domestic reindeer).

 

What was once the second largest herd is the migratory Labrador caribou (R. t. caboti)[9] George River herd in Canada, with former variations between 28,000 and 385,000. As of January 2018, there are fewer than 9,000 animals estimated to be left in the George River herd, as reported by the Canadian Broadcasting Corporation. The New York Times reported in April 2018 of the disappearance of the only herd of southern mountain woodland caribou in the contiguous United States, with an expert calling it "functionally extinct" after the herd's size dwindled to a mere three animals. After the last individual, a female, was translocated to a wildlife rehabilitation center in Canada, caribou were considered extirpated from the contiguous United States. The Committee on Status of Endangered Wildlife in Canada (COSEWIC) classified both the Southern Mountain population DU9 (R. t. montanus) and the Central Mountain population DU8 (R. t. fortidens) as Endangered and the Northern Mountain population DU7 (R. t. osborni) as Threatened.

 

Some species and subspecies are rare and three subspecies have already become extinct: the Queen Charlotte Islands caribou (R. t. dawsoni) from western Canada, the Sakhalin reindeer (R. t. setoni) from Sakhalin and the East Greenland caribou from eastern Greenland, although some authorities believe that the latter, R. t. eogroenlandicus Degerbøl, 1957, is a junior synonym of the Peary caribou Historically, the range of the sedentary boreal woodland caribou covered more than half of Canada and into the northern states of the contiguous United States from Maine to Washington. Boreal woodland caribou have disappeared from most of their original southern range and were designated as Threatened in 2002 by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). Environment Canada reported in 2011 that there were approximately 34,000 boreal woodland caribou in 51 ranges remaining in Canada (Environment Canada, 2011b), although those numbers included montane populations classified by Harding (2022) into subspecies of the Arctic caribou. Siberian tundra reindeer herds are also in decline, and Rangifer as a whole is considered to be Vulnerable by the IUCN.

 

Naming

Charles Hamilton Smith is credited with the name Rangifer for the reindeer genus, which Albertus Magnus used in his De animalibus, fol. Liber 22, Cap. 268: "Dicitur Rangyfer quasi ramifer". This word may go back to the Sámi word raingo. Carl Linnaeus chose the word tarandus as the specific epithet, making reference to Ulisse Aldrovandi's Quadrupedum omnium bisulcorum historia fol. 859–863, Cap. 30: De Tarando (1621). However, Aldrovandi and Conrad Gessner thought that rangifer and tarandus were two separate animals, In any case, the tarandos name goes back to Aristotle and Theophrastus.

 

The use of the terms reindeer and caribou for essentially the same animal can cause confusion, but the International Union for Conservation of Nature clearly delineates the issue: "Reindeer is the European name for the species of Rangifer, while in North America, Rangifer species are known as Caribou." The word reindeer is an anglicized version of the Old Norse words hreinn (“reindeer”) and dýr (“animal”) and has nothing to do with reins. The word caribou comes through French, from the Mi'kmaq qalipu, meaning "snow shoveler", and refers to its habit of pawing through the snow for food.

 

Because of its importance to many cultures, Rangifer and some of its species and subspecies have names in many languages. Inuvaluit of the western Canadian Arctic and Inuit of the eastern Canadian Arctic, who speak different dialects of Inuktitut, both call the barren-ground caribou tuktu. The Wekʼèezhìi people, a Dene (Athapascan) group, call the Arctic caribou ekwǫ̀ and the boreal woodland caribou tǫdzı. The Gwichʼin (also a Dene group) have over 24 distinct caribou-related words.

 

Reindeer are also called tuttu by the Greenlandic Inuit and hreindýr, sometimes rein, by the Icelanders.

 

Evolution

The "glacial-interglacial cycles of the upper Pleistocene had a major influence on the evolution" of Rangifer species and other Arctic and sub-Arctic species. Isolation of tundra-adapted species Rangifer in Last Glacial Maximum refugia during the last glacial – the Wisconsin glaciation in North America and the Weichselian glaciation in Eurasia – shaped "intraspecific genetic variability" particularly between the North American and Eurasian parts of the Arctic.

 

Reindeer/caribou (Rangifer) are in the subfamily Odocoileinae, along with roe deer (Capreolus), Eurasian elk/moose (Alces), and water deer (Hydropotes). These antlered cervids split from the horned ruminants Bos (cattle and yaks), Ovis (sheep) and Capra (goats) about 36 million years ago. The Eurasian clade of Odocoileinae (Capreolini, Hydropotini and Alcini) split from the New World tribes of Capreolinae (Odocoileini and Rangiferini) in the Late Miocene, 8.7–9.6 million years ago. Rangifer “evolved as a mountain deer, ...exploiting the subalpine and alpine meadows...”. Rangifer originated in the Late Pliocene and diversified in the Early Pleistocene, a 2+ million-year period of multiple glacier advances and retreats. Several named Rangifer fossils in Eurasia and North America predate the evolution of modern tundra reindeer.

 

Archaeologists distinguish “modern” tundra reindeer and barren-ground caribou from primitive forms — living and extinct — that did not have adaptations to extreme cold and to long distance migration. They include a broad, high muzzle to increase the volume of the nasal cavity to warm and moisten the air before it enters the throat and lungs, bez tines set close to the brow tines, distinctive coat patterns, short legs and other adaptations for running long distances, and multiple behaviors suited to tundra, but not to forest (such as synchronized calving and aggregation during rutting and post-calving). As well, many genes, including those for vitamin D metabolism, fat metabolism, retinal development, circadian rhythm, and tolerance to cold temperatures, are found in tundra caribou that are lacking or rudimentary in forest types. For this reason, forest-adapted reindeer and caribou could not survive in tundra or polar deserts. The oldest undoubted Rangifer fossil is from Omsk, Russia, dated to 2.1-1.8 Ma. The oldest North American Rangifer fossil is from the Yukon, 1.6 million years before present (BP). A fossil skull fragment from Süßenborn, Germany, R. arcticus stadelmanni, (which is probably misnamed) with “rather thin and cylinder-shaped” antlers, dates to the Middle Pleistocene (Günz) Period, 680,000-620,000 BP. Rangifer fossils become increasingly frequent in circumpolar deposits beginning with the Riss glaciations, the second youngest of the Pleistocene Epoch, roughly 300,000–130,000 BP. By the 4-Würm period (110,000–70,000 to 12,000–10,000 BP), its European range was extensive, supplying a major food source for prehistoric Europeans. North American fossils outside of Beringia that predate the Last Glacial Maximum (LGM) are of Rancholabrean age (240,000–11,000 years BP) and occur along the fringes of the Rocky Mountain and Laurentide ice sheets as far south as northern Alabama; and in Sangamonian deposits (~100,000 years BP) from western Canada.

 

A R. t. pearyi-sized caribou occupied Greenland before and after the LGM and persisted in a relict enclave in northeastern Greenland until it went extinct about 1900 (see discussion of R. t. eogroenlandicus below). Archaeological excavations showed that larger barren-ground-sized caribou appeared in western Greenland about 4,000 years ago.

 

The late Valerius Geist (1998) dates the Eurasian reindeer radiation dates to the large Riss glaciation (347,000 to 128,000 years ago), based on the Norwegian-Svalbard split 225,000 years ago. Finnish forest reindeer (R. t. fennicus) likely evolved from Cervus [Rangifer] geuttardi Desmarest, 1822, a reindeer that adapted to forest habitats in Eastern Europe as forests expanded during an interglacial period before the LGM (the Würmian or Weichsel glaciation);. The fossil species geuttardi was later replaced by R. constantini, which was adapted for grasslands, in a second immigration 19,000–20,000 years ago when the LGM turned its forest habitats into tundra, while fennicus survived in isolation in southwestern Europe. R. constantini was then replaced by modern tundra/barren-ground caribou adapted to extreme cold, probably in Beringia, before dispersing west (R. t. tarandus in the Scandinavian mountains and R. t. sibiricus across Siberia) and east (R. t. arcticus in the North American Barrenlands) when rising seas isolated them. Likewise in North America, DNA analysis shows that woodland caribou (R. caribou) diverged from primitive ancestors of tundra/barren-ground caribou not during the LGM, 26,000–19,000 years ago, as previously assumed, but in the Middle Pleistocene around 357,000 years ago. At that time, modern tundra caribou had not even evolved. Woodland caribou are likely more related to extinct North American forest caribou than to barren-ground caribou. For example, the extinct caribou Torontoceros [Rangifer] hypogaeus, had features (robust and short pedicles, smooth antler surface, and high position of second tine) that relate it to forest caribou.

 

Humans started hunting reindeer in both the Mesolithic and Neolithic Periods, and humans are today the main predator in many areas. Norway and Greenland have unbroken traditions of hunting wild reindeer from the Last Glacial Period until the present day. In the non-forested mountains of central Norway, such as Jotunheimen, it is still possible to find remains of stone-built trapping pits, guiding fences and bow rests, built especially for hunting reindeer. These can, with some certainty, be dated to the Migration Period, although it is not unlikely that they have been in use since the Stone Age.

 

Cave paintings by ancient Europeans include both tundra and forest types of reindeer.

 

A 2022 study of ancient environmental DNA from the Early Pleistocene (2 million years ago) Kap Kobenhavn Formation of northern Greenland identified preserved DNA fragments of Rangifer, identified as basal but potentially ancestral to modern reindeer. This suggests that reindeer have inhabited Greenland since at least the Early Pleistocene. Around this time, northern Greenland was 11–19 °C warmer than the Holocene, with a boreal forest hosting a species assemblage with no modern analogue. These are among the oldest DNA fragments ever sequenced.

 

Taxonomy

Carl Linnaeus in 1758 named the Eurasian tundra species Cervus tarandus, the genus Rangifer being credited to Smith, 1827.

 

Rangifer has had a convoluted history because of the similarity in antler architecture (brow tines asymmetrical and often palmate, bez tines, a back tine sometimes branched, and branched at the distal end, often palmate). Because of individual variability, early taxonomists were unable to discern consistent patterns among populations, nor could they, examining collections in Europe, appreciate the difference in habitats and the differing function they imposed on antler architecture. For example, woodland caribou males, rutting in boreal forest where only a few females can be found, collect harems and defend them against other males, for which they have short, straight, strong, much-branched antlers, beams flattened in cross-section, designed for combat — and not too large, so as not to impede them in forested winter ranges. By contrast, modern tundra caribou (see Evolution above) have synchronized calving as a predator-avoidance strategy, which requires large rutting aggregations. Males cannot defend a harem because, while he was busy fighting, they would disappear into the mass of the herd. Males therefore tend individual females; their fights are infrequent and brief. Their antlers are thin, beams round in cross-section, sweep back and then forward with a cluster of branches at the top; these are designed more for visual stimulation of the females. Their bez tines are set low, just above the brow tine, which is vertically flattened to protect the eyes while the buck "threshes" low brush, a courtship display. The low bez tines help the wide flat brow tines dig craters in the hard-packed tundra snow for forage, for which reason brow tines are often called "shovels" in North America and "ice tines" in Europe. The differences in antler architecture reflect fundamental differences in ecology and behavior, and in turn deep divisions in ancestry that were not apparent to the early taxonomists.

 

Similarly, working on museum collections where skins were often faded and in poor states of preservation, early taxonomists could not readily perceive differences in coat patterns that are consistent within a subspecies, but variable among them. Geist calls these "nuptial" characteristics: sexually selected characters that are highly conserved and diagnostic among subspecies.

 

Towards the end of the 19th century, national museums began sending out biological exploration expeditions and collections accumulated. Taxonomists, usually working for the museums began naming subspecies more rigorously, based on statistical differences in detailed cranial, dental and skeletal measurements than antlers and pelage, supplemented by better knowledge of differences in ecology and behavior. From 1898 to 1937, mammalogists named 12 new species (other than barren-ground and woodland, which had been named earlier) of caribou in Canada and Alaska, and three new species and nine new subspecies in Eurasia, each properly described according to the evolving rules of zoological nomenclature, with type localities designated and type specimens deposited in museums.

 

In the mid-20th century, as definitions of "species" evolved, mammalogists in Europe and North America made all Rangifer species conspecific with R. tarandus, and synonymized most of the subspecies. Banfield's often-cited A Revision of the Reindeer and Caribou, Genus Rangifer (1961), eliminated R. t. caboti (the Labrador caribou), R. t. osborni (Osborn's caribou — from British Columbia) and R. t. terranovae (the Newfoundland caribou) as invalid and included only barren-ground caribou, renamed as R. t. groenlandicus (formerly R. arcticus) and woodland caribou as R. t. caribou. However, Banfield made multiple errors, eliciting a scathing review by Ian McTaggart-Cowan in 1962 Most authorities continued to consider all or most subspecies valid; some were quite distinct. In his chapter in the authoritative 2005 reference work Mammal Species of the World, referenced by the American Society of Mammalogists, English zoologist Peter Grubb agreed with Valerius Geist, a specialist on large mammals, that these subspecies were valid (i.e., before the recent revision): In North America, R. t. caboti, R. t. caribou, R. t. dawsoni, R. t. groenlandicus, R. t. osborni, R. t. pearyi, and R. t. terranovae; and in Eurasia, R. t. tarandus, R. t. buskensis (called R. t. valentinae in Europe; see below), R. t. phylarchus, R. t. pearsoni, R. t. sibiricus and R. t. platyrhynchus. These subspecies were retained in the 2011 replacement work Handbook of Mammals of the World Vol. 2: Hoofed Mammals.[8] Most Russian authors also recognized R. t. angustirostris, a forest reindeer from east of Lake Baikal.

 

However, since 1991, many genetic studies have revealed deep divergence between modern tundra reindeer and woodland caribou. Geist (2007) and others continued arguing that the woodland caribou was incorrectly classified, noting that "true woodland caribou, the uniformly dark, small-maned type with the frontally emphasized, flat-beamed antlers", is "scattered thinly along the southern rim of North American caribou distribution". He affirms that the "true woodland caribou is very rare, in very great difficulties and requires the most urgent of attention."

 

In 2011, noting that the former classifications of Rangifer tarandus, either with prevailing taxonomy on subspecies, designations based on ecotypes, or natural population groupings, failed to capture "the variability of caribou across their range in Canada" needed for effective subspecies conservation and management, COSEWIC developed Designatable Unit (DU) attribution, an adaptation of "evolutionary significant units". The 12 designatable units for caribou in Canada (that is, excluding Alaska and Greenland) based on ecology, behavior and, importantly, genetics (but excluding morphology and archaeology) essentially followed the previously-named subspecies distributions, without naming them as such, plus some ecotypes. Ecotypes are not phylogenetically based and cannot substitute for taxonomy.

 

Meanwhile, genetic data continued to accumulate, revealing sufficiently deep divisions to easily separate Rangifer back into six previously named species and to resurrect several previously named subspecies. Molecular data showed that the Greenland caribou (R. t. groenlandicus) and the Svalbard reindeer (R. t. platyrhynchus), although not closely related to each other, were the most genetically divergent among Rangifer clades; that modern (see Evolution above) Eurasian tundra reindeer (R. t. tarandus and R. t. sibiricus) and North American barren-ground caribou (R. t. arcticus), although sharing ancestry, were separable at the subspecies level; that Finnish forest reindeer (R. t. fennicus) clustered well apart from both wild and domestic tundra reindeer and that boreal woodland caribou (R. t. caribou) were separable from all others. Meanwhile, archaeological evidence was accumulating that Eurasian forest reindeer descended from an extinct forest-adapted reindeer and not from tundra reindeer; since they do not share a direct common ancestor, they cannot be conspecific. Similarly, woodland caribou diverged from the ancestors of Arctic caribou before modern barren-ground caribou had evolved, and were more likely related to extinct North American forest reindeer. Lacking a direct shared ancestor, barren-ground and woodland caribou cannot be conspecific.

 

Molecular data also revealed that the four western Canadian montane ecotypes are not woodland caribou: they share a common ancestor with modern barren-ground caribou/tundra reindeer, but distantly, having diverged > 60,000 years ago — before the modern ecotypes had evolved their cold- and darkness-adapted physiologies and mass-migration and aggregation behaviors (see Evolution above). Before Banfield (1961), taxonomists using cranial, dental and skeletal measurements had unequivocally allied these western montane ecotypes with barren-ground caribou, naming them (as in Osgood 1909[85] Murie, 1935 and Anderson 1946, among others) R. t. stonei, R. t. montanus, R. t. fortidens and R. t. osborni, respectively, and this phylogeny was confirmed by genetic analysis.

 

DNA also revealed three unnamed clades that, based on genetic distance, genetic divergence and shared vs. private haplotypes and alleles, together with ecological and behavioral differences, may justify separation at the subspecies level: the Atlantic-Gaspésie caribou (COSEWIC DU11), an eastern montane ecotype of the boreal woodland caribou, and the Baffin Island caribou. Neither one of these clades has yet been formally described or named.

 

Jenkins et al. (2012) said that "[Baffin Island] caribou are unique compared to other Barrenground herds, as they do not overwinter in forested habitat, nor do all caribou undertake long seasonal migrations to calving areas." It also shares a mtDNA haplotype with Labrador caribou, in the North American lineage (i.e., woodland caribou). Røed et al. (1991) had noted:

 

Among Baffin Island caribou the TFL2 allele was the most common allele (p=0.521), while this allele was absent, or present in very low frequencies, in other caribou populations , including the Canadian barren-ground caribou from the Beverly herd. A large genetic difference between Baffin Island caribou and the Beverly herd was also indicated by eight alleles found in the Beverly herd which were absent from the Baffin Island samples.

 

Jenkins et al. (2018) also reported genetic distinctiveness of Baffin Island caribou from all other barren-ground caribou; its genetic signature was not found on the mainland or on other islands; nor were Beverly herd (the nearest mainly barren-ground caribou) alleles present in Baffin Island caribou, evidence of reproductive isolation.

 

These advances in Rangifer genetics were brought together with previous morphological-based descriptions, ecology, behavior and archaeology to propose a new revision of the genus.

 

The scientific name Tarandus rangifer buskensis Millais, 1915 (the Busk Mountains reindeer) was selected as the senior synonym to R. t. valentinae Flerov, 1933, in Mammal Species of the World but Russian authors do not recognize Millais and Millais' articles in a hunting travelogue, The Gun at Home and Abroad, seem short of a taxonomic authority.

 

The scientific name groenlandicus is fraught with problems. Edwards (1743) illustrated and claimed to have seen a male specimen (“head of perfect horns...”) from Greenland and said that a Captain Craycott had brought a live pair from Greenland to England in 1738. He named it Capra groenlandicus, Greenland reindeer. Linnaeus, in the 12th edition of Systema naturae, gave grœnlandicus as a synonym for Cervus tarandus. Borowski disagreed (and again changed the spelling), saying Cervus grönlandicus was morphologically distinct from Eurasian tundra reindeer. Baird placed it under the genus Rangifer as R. grœnlandicus. It went back and forth as a full species or subspecies of the barren-ground caribou (R. arcticus) or a subspecies of the tundra reindeer (R. tarandus), but always as the Greenland reindeer/caribou. Taxonomists consistently documented morphological differences between Greenland and other caribou/reindeer in cranial measurements, dentition, antler architecture, etc. Then Banfield (1961) in his famously flawed revision, gave the name groenlandicus to all the barren-ground caribou in North America, Greenland included, because groenlandicus pre-dates Richardson’s R. arctus,. However, because genetic data shows the Greenland caribou to be the most distantly related of any caribou to all the others (genetic distance, FST = 44%, whereas most cervid (deer family) species have a genetic distance of 2% to 5%)--as well as behavioral and morphological differences—a recent revision returned it to species status as R. groenlandicus. Although it has been assumed that the larger caribou that appeared in Greenland 4,000 years ago originated from Baffin Island (itself unique; see Taxonomy above), a reconstruction of LGM glacial retreat and caribou advance (Yannic et al. 2013) shows colonization by NAL lineage caribou more likely. Their PCA and tree diagrams show Greenland caribou clustering outside of the Beringian-Eurasian lineage.

 

The scientific name R. t. granti has a very interesting history. Allen (1902) named it as a distinct species, R. granti, from the "western end of Alaska Peninsula, opposite Popoff Island" and noting that:

 

Rangifer granti is a representative of the Barren Ground group of Caribou, which includes R. arcticus of the Arctic Coast and R. granlandicus of Greenland. It is not closely related to R. stonei of the Kenai Peninsula, from which it differs not only in its very much smaller size, but in important cranial characters and in coloration. ...The external and cranial differences between R. granti and the various forms of the Woodland Caribou are so great in almost every respect that no detailed comparison is necessary. ...According to Mr. Stone, Rangifer granti inhabits the " barren land of Alaska Peninsula, ranging well up into the mountains in summer, but descending to the lower levels in winter, generally feeding on the low flat lands near the coast and in the foothills...As regards cranial characters no comparison is necessary with R. montanus or with any of the woodland forms."

 

Osgood and Murie (1935), agreeing with granti's close relationship with the barren-ground caribou, brought it under R. arcticus as a subspecies, R. t. granti. Anderson (1946) and Banfield (1961), based on statistical analysis of cranial, dental and other characters, agreed. But Banfield (1961) also synonymized Alaska's large R. stonei with other mountain caribou of British Columbia and the Yukon as invalid subspecies of woodland caribou, then R. t. caribou. This left the small, migratory barren-ground caribou of Alaska and the Yukon, including the Porcupine caribou herd, without a name, which Banfield rectified in his 1974 Mammals of Canada by extending to them the name "granti". The late Valerius Geist (1998), in the only error in his whole illustrious career, re-analyzed Banfield's data with additional specimens found in an unpublished report he cites as "Skal, 1982", but was "not able to find diagnostic features that could segregate this form from the western barren ground type." But Skal 1982 had included specimens from the eastern end of the Alaska Peninsula and the Kenai Peninsula, the range of the larger Stone's caribou. Later, geneticists comparing barren-ground caribou of Alaska with those of mainland Canada found little difference and they all became the former R. t. groenlandicus (now R. t. arcticus). R. t. granti was lost in the oblivion of invalid taxonomy until Alaskan researchers sampled some small, pale caribou from the western end of the Alaska Peninsula, their range enclosing the type locality designated by Allen (1902) and found them to be genetically distinct from all other caribou in Alaska. Thus, granti was rediscovered, its range restricted to that originally described.

 

Stone's caribou (R. t. stonei), a large montane type, was described from the Kenai Peninsula (where, apparently, it was never common except in years of great abundance), the eastern end of the Alaska Peninsula, and mountains throughout southern and eastern Alaska. It was placed under R. arcticus as a subspecies, R. t. stonei, and later synonymised as noted above. The same genetic analyses mentioned above for R. t. granti resulted in resurrecting R. t. stonei as well.

 

The Sakhalin reindeer (R. t. setoni), endemic to Sakhalin, was described as Rangifer tarandus setoni Flerov, 1933, but Banfield (1961) brought it under R. t. fennicus as a junior synonym. The wild reindeer on the island are apparently extinct, having been replaced by domestic reindeer.

 

Some of the Rangifer species and subspecies may be further divided by ecotype depending on several behavioral factors – predominant habitat use (northern, tundra, mountain, forest, boreal forest, forest-dwelling, woodland, woodland (boreal), woodland (migratory) or woodland (mountain), spacing (dispersed or aggregated) and migration patterns (sedentary or migratory). North American examples of this are the Torngat Mountain population DU10, an ecotype of R. t. caboti; a recently discovered and unnamed clade between the Mackenzie River and Great Bear Lake of Beringian-Eurasian lineage, an ecotype of R. t. osborni; the Atlantic-Gaspésie population DU11, an eastern montane ecotype of the boreal woodland caribou (R. t. caribou); the Baffin Island caribou, an ecotype of the barren-ground caribou (R. t. arcticus); and the Dolphin-Union “herd”, another ecotype of R. t. arcticus. The last three of these likely qualify as subspecies, but they have not yet been formally described or named.

 

Physical characteristics

Naming in this and following sections follows the taxonomy in the authoritative 2011 reference work Handbook of Mammals of the World Vol. 2: Hoofed Mammals.

 

Antlers

In most cervid species, only males grow antlers; the reindeer is the only cervid species in which females also grow them normally. Androgens play an essential role in the antler formation of cervids. The antlerogenic genes in reindeer have more sensitivity to androgens in comparison with other cervids.

 

There is considerable variation among species and subspecies in the size of the antlers (e.g., they are rather small and spindly in the northernmost species and subspecies), but on average the bull's antlers are the second largest of any extant deer, after those of the male moose. In the largest subspecies, the antlers of large bulls can range up to 100 cm (39 in) in width and 135 cm (53 in) in beam length. They have the largest antlers relative to body size among living deer species.[116] Antler size measured in number of points reflects the nutritional status of the reindeer and climate variation of its environment. The number of points on male reindeer increases from birth to 5 years of age and remains relatively constant from then on.  "In male caribou, antler mass (but not the number of tines) varies in concert with body mass." While antlers of male woodland caribou are typically smaller than those of male barren-ground caribou, they can be over 1 m (3 ft 3 in) across. They are flattened in cross-section, compact and relatively dense.[36] Geist describes them as frontally emphasized, flat-beamed antlers. Woodland caribou antlers are thicker and broader than those of the barren-ground caribou and their legs and heads are longer. Quebec-Labrador male caribou antlers can be significantly larger and wider than other woodland caribou. Central barren-ground male caribou antlers are perhaps the most diverse in configuration and can grow to be very high and wide. Osborn's caribou antlers are typically the most massive, with the largest circumference measurements.

 

The antlers' main beams begin at the brow "extending posterior over the shoulders and bowing so that the tips point forward. The prominent, palmate brow tines extend forward, over the face." The antlers typically have two separate groups of points, lower and upper.

 

Antlers begin to grow on male reindeer in March or April and on female reindeer in May or June. This process is called antlerogenesis. Antlers grow very quickly every year on the bulls. As the antlers grow, they are covered in thick velvet, filled with blood vessels and spongy in texture. The antler velvet of the barren-ground caribou and the boreal woodland caribou is dark chocolate brown. The velvet that covers growing antlers is a highly vascularised skin. This velvet is dark brown on woodland or barren-ground caribou and slate-grey on Peary caribou and the Dolphin-Union caribou herd. Velvet lumps in March can develop into a rack measuring more than a meter in length (3 ft) by August.

  

A R. tarandus skull

When the antler growth is fully grown and hardened, the velvet is shed or rubbed off. To the Inuit, for whom the caribou is a "culturally important keystone species", the months are named after landmarks in the caribou life cycle. For example, amiraijaut in the Igloolik region is "when velvet falls off caribou antlers."

 

Male reindeer use their antlers to compete with other males during the mating season. Butler (1986) showed that the social requirements of caribou females during the rut determines the mating strategies of males and, consequently, the form of male antlers. In describing woodland caribou, which have a harem-defense mating system, SARA wrote, "During the rut, males engage in frequent and furious sparring battles with their antlers. Large males with large antlers do most of the mating." Reindeer continue to migrate until the bulls have spent their back fat. By contrast, barren-ground caribou males tend individual females and their fights are brief and much less intense; consequently, their antlers are long, and thin, round in cross-section and less branched and are designed more for show (or sexual attraction) than fighting.

 

In late autumn or early winter after the rut, male reindeer lose their antlers, growing a new pair the next summer with a larger rack than the previous year. Female reindeer keep their antlers until they calve. In the Scandinavian and Arctic Circle populations, old bulls' antlers fall off in late December, young bulls' antlers fall off in the early spring, and cows' antlers fall off in the summer.

 

When male reindeer shed their antlers in early to mid-winter, the antlered cows acquire the highest ranks in the feeding hierarchy, gaining access to the best forage areas. These cows are healthier than those without antlers. Calves whose mothers do not have antlers are more prone to disease and have a significantly higher mortality. Cows in good nutritional condition, for example, during a mild winter with good winter range quality, may grow new antlers earlier as antler growth requires high intake.

  

A R. t. platyrhynchus skull

According to a respected Igloolik elder, Noah Piugaattuk, who was one of the last outpost camp leaders, caribou (tuktu) antlers

 

...get detached every year...Young males lose the velvet from the antlers much more quickly than female caribou even though they are not fully mature. They start to work with their antlers just as soon as the velvet starts to fall off. The young males engage in fights with their antlers towards autumn...soon after the velvet had fallen off they will be red, as they start to get bleached their colour changes...When the velvet starts to fall off the antler is red because the antler is made from blood. The antler is the blood that has hardened; in fact, the core of the antler is still bloody when the velvet starts to fall off, at least close to the base.

 

— Elder Noah Piugaattuk of Igloolik cited in "Tuktu — Caribou" (2002) "Canada's Polar Life"

According to the Igloolik Oral History Project (IOHP), "Caribou antlers provided the Inuit with a myriad of implements, from snow knives and shovels to drying racks and seal-hunting tools. A complex set of terms describes each part of the antler and relates it to its various uses". Currently, the larger racks of antlers are used by Inuit as materials for carving. Iqaluit-based Jackoposie Oopakak's 1989 carving, entitled Nunali, which means "place where people live", and which is part of the permanent collection of the National Gallery of Canada, includes a massive set of caribou antlers on which he has intricately carved the miniaturized world of the Inuit where "Arctic birds, caribou, polar bears, seals, and whales are interspersed with human activities of fishing, hunting, cleaning skins, stretching boots, and travelling by dog sled and kayak...from the base of the antlers to the tip of each branch".

 

Pelt

The color of the fur varies considerably, both between individuals and depending on season and species. Northern populations, which usually are relatively small, are whiter, while southern populations, which typically are relatively large, are darker. This can be seen well in North America, where the northernmost subspecies, the Peary caribou, is the whitest and smallest subspecies of the continent, while the Selkirk Mountains caribou (Southern Mountain population DU9) is the darkest and nearly the largest, only exceeded in size by Osborn's caribou (Northern Mountain population DU7).

 

The coat has two layers of fur: a dense woolly undercoat and a longer-haired overcoat consisting of hollow, air-filled hairs. Fur is the primary insulation factor that allows reindeer to regulate their core body temperature in relation to their environment, the thermogradient, even if the temperature rises to 38 °C (100 °F). In 1913, Dugmore noted how the woodland caribou swim so high out of the water, unlike any other mammal, because their hollow, "air-filled, quill-like hair" acts as a supporting "life jacket".

 

A darker belly color may be caused by two mutations of MC1R. They appear to be more common in domestic reindeer herds.

 

Heat exchange

Blood moving into the legs is cooled by blood returning to the body in a countercurrent heat exchange (CCHE), a highly efficient means of minimizing heat loss through the skin's surface. In the CCHE mechanism, in cold weather, blood vessels are closely knotted and intertwined with arteries to the skin and appendages that carry warm blood with veins returning to the body that carry cold blood causing the warm arterial blood to exchange heat with the cold venous blood. In this way, their legs for example are kept cool, maintaining the core body temperature nearly 30 °C (54 °F) higher with less heat lost to the environment. Heat is thus recycled instead of being dissipated. The "heart does not have to pump blood as rapidly in order to maintain a constant body core temperature and thus, metabolic rate." CCHE is present in animals like reindeer, fox and moose living in extreme conditions of cold or hot weather as a mechanism for retaining the heat in (or out of) the body. These are countercurrent exchange systems with the same fluid, usually blood, in a circuit, used for both directions of flow.

 

Reindeer have specialized counter-current vascular heat exchange in their nasal passages. Temperature gradient along the nasal mucosa is under physiological control. Incoming cold air is warmed by body heat before entering the lungs and water is condensed from the expired air and captured before the reindeer's breath is exhaled, then used to moisten dry incoming air and possibly be absorbed into the blood through the mucous membranes. Like moose, caribou have specialized noses featuring nasal turbinate bones that dramatically increase the surface area within the nostrils.

 

Hooves

The reindeer has large feet with crescent-shaped cloven hooves for walking in snow or swamps. According to the Species at Risk Public Registry (SARA), woodland

 

"Caribou have large feet with four toes. In addition to two small ones, called "dew claws," they have two large, crescent-shaped toes that support most of their weight and serve as shovels when digging for food under snow. These large concave hooves offer stable support on wet, soggy ground and on crusty snow. The pads of the hoof change from a thick, fleshy shape in the summer to become hard and thin in the winter months, reducing the animal's exposure to the cold ground. Additional winter protection comes from the long hair between the "toes"; it covers the pads so the caribou walks only on the horny rim of the hooves."

 

— SARA 2014

Reindeer hooves adapt to the season: in the summer, when the tundra is soft and wet, the footpads become sponge-like and provide extra traction. In the winter, the pads shrink and tighten, exposing the rim of the hoof, which cuts into the ice and crusted snow to keep it from slipping. This also enables them to dig down (an activity known as "cratering") through the snow to their favourite food, a lichen known as reindeer lichen (Cladonia rangiferina).

 

Size

The females (or "cows" as they are often called) usually measure 162–205 cm (64–81 in) in length and weigh 80–120 kg (180–260 lb). The males (or "bulls" as they are often called) are typically larger (to an extent which varies between the different species and subspecies), measuring 180–214 cm (71–84 in) in length and usually weighing 159–182 kg (351–401 lb). Exceptionally large bulls have weighed as much as 318 kg (701 lb). Weight varies drastically between the seasons, with bulls losing as much as 40% of their pre-rut weight.

 

The shoulder height is usually 85 to 150 cm (33 to 59 in), and the tail is 14 to 20 cm (5.5 to 7.9 in) long.

 

The reindeer from Svalbard are the smallest of all. They are also relatively short-legged and may have a shoulder height of as little as 80 cm (31 in), thereby following Allen's rule.

 

Clicking sound

The knees of many species and subspecies of reindeer are adapted to produce a clicking sound as they walk. The sounds originate in the tendons of the knees and may be audible from several hundred meters away. The frequency of the knee-clicks is one of a range of signals that establish relative positions on a dominance scale among reindeer. "Specifically, loud knee-clicking is discovered to be an honest signal of body size, providing an exceptional example of the potential for non-vocal acoustic communication in mammals." The clicking sound made by reindeer as they walk is caused by small tendons slipping over bone protuberances (sesamoid bones) in their feet. The sound is made when a reindeer is walking or running, occurring when the full weight of the foot is on the ground or just after it is relieved of the weight.

 

Eyes

A study by researchers from University College London in 2011 revealed that reindeer can see light with wavelengths as short as 320 nm (i.e. in the ultraviolet range), considerably below the human threshold of 400 nm. It is thought that this ability helps them to survive in the Arctic, because many objects that blend into the landscape in light visible to humans, such as urine and fur, produce sharp contrasts in ultraviolet. It has been proposed that UV flashes on power lines are responsible for reindeer avoiding power lines because "...in darkness these animals see power lines not as dim, passive structures but, rather, as lines of flickering light stretching across the terrain."

 

In 2023, researchers studying reindeer living in Cairngorms National Park, Scotland, suggested that UV visual sensitivity in reindeer helps them detect UV-absorbing lichens against a background of UV-reflecting snows.

 

The tapetum lucidum of Arctic reindeer eyes changes in color from gold in summer to blue in winter to improve their vision during times of continuous darkness, and perhaps enable them to better spot predators.

 

Biology and behaviors

Reindeer have developed adaptations for optimal metabolic efficiency during warm months as well as for during cold months. The body composition of reindeer varies highly with the seasons. Of particular interest is the body composition and diet of breeding and non-breeding females between the seasons. Breeding females have more body mass than non-breeding females between the months of March and September with a difference of around 10 kg (22 lb) more than non-breeding females. From November to December, non-breeding females have more body mass than breeding females, as non-breeding females are able to focus their energies towards storage during colder months rather than lactation and reproduction. Body masses of both breeding and non-breeding females peaks in September. During the months of March through April, breeding females have more fat mass than the non-breeding females with a difference of almost 3 kg (6.6 lb). After this, however, non-breeding females on average have a higher body fat mass than do breeding females.

 

The environmental variations play a large part in reindeer nutrition, as winter nutrition is crucial to adult and neonatal survival rates. Lichens are a staple during the winter months as they are a readily available food source, which reduces the reliance on stored body reserves. Lichens are a crucial part of the reindeer diet; however, they are less prevalent in the diet of pregnant reindeer compared to non-pregnant individuals. The amount of lichen in a diet is found more in non-pregnant adult diets than pregnant individuals due to the lack of nutritional value. Although lichens are high in carbohydrates, they are lacking in essential proteins that vascular plants provide. The amount of lichen in a diet decreases in latitude, which results in nutritional stress being higher in areas with low lichen abundance. 

 

In a study of seasonal light-dark cycles on sleep patterns of female reindeer, researchers performed non-invasive electroencephalography (EEG) on reindeer kept in a stable at the UiT The Arctic University of Norway. The EEG recordings showed that: the more time reindeer spend ruminating, the less time they spend in non-rapid eye movement sleep (NREM sleep); and reindeer's brainwaves during rumination resemble the brainwaves present during NREM sleep. These results suggest that, by reducing the time requirement for NREM sleep, reindeer are able to spend more time feeding during the summer months, when food is abundant.

 

Reproduction and life cycle

Reindeer mate in late September to early November, and the gestation period is about 228–234 days. During the mating season, bulls battle for access to cows. Two bulls will lock each other's antlers together and try to push each other away. The most dominant bulls can collect as many as 15–20 cows to mate with. A bull will stop eating during this time and lose much of his body fat reserves.

 

To calve, "females travel to isolated, relatively predator-free areas such as islands in lakes, peatlands, lake-shores, or tundra." As females select the habitat for the birth of their calves, they are warier than males. Dugmore noted that, in their seasonal migrations, the herd follows a female for that reason. Newborns weigh on average 6 kg (13 lb).[148] In May or June, the calves are born. After 45 days, the calves are able to graze and forage, but continue suckling until the following autumn when they become independent from their mothers.

 

Bulls live four years less than the cows, whose maximum longevity is about 17 years. Cows with a normal body size and who have had sufficient summer nutrition can begin breeding anytime between the ages of 1 and 3 years. When a cow has undergone nutritional stress, it is possible for her to not reproduce for the year. Dominant bulls, those with larger body size and antler racks, inseminate more than one cow a season.

 

Social structure, migration and range

Some populations of North American caribou; for example, many herds in the barren-ground caribou subspecies and some woodland caribou in Ungava and northern Labrador, migrate the farthest of any terrestrial mammal, traveling up to 5,000 km (3,000 mi) a year, and covering 1,000,000 km2 (400,000 sq mi). Other North American populations, the boreal woodland caribou for example, are largely sedentary. The European populations are known to have shorter migrations. Island populations, such as the Novaya Zemlya and Svalbard reindeer and the Peary caribou, make local movements both within and among islands. Migrating reindeer can be negatively affected by parasite loads. Severely infected individuals are weak and probably have shortened lifespans, but parasite levels vary between populations. Infections create an effect known as culling: infected migrating animals are less likely to complete the migration.

 

Normally travelling about 19–55 km (12–34 mi) a day while migrating, the caribou can run at speeds of 60–80 km/h (37–50 mph).[2] Young calves can already outrun an Olympic sprinter when only 1 day old. During the spring migration, smaller herds will group together to form larger herds of 50,000 to 500,000 animals, but during autumn migrations, the groups become smaller and the reindeer begin to mate. During winter, reindeer travel to forested areas to forage under the snow. By spring, groups leave their winter grounds to go to the calving grounds. A reindeer can swim easily and quickly, normally at about 6.5 km/h (4.0 mph) but, if necessary, at 10 km/h (6.2 mph) and migrating herds will not hesitate to swim across a large lake or broad river.

 

The barren-ground caribou form large herds and undertake lengthy seasonal migrations from winter feeding grounds in taiga to spring calving grounds and summer range in the tundra. The migrations of the Porcupine herd of barren-ground caribou are among the longest of any mammal. Greenland caribou, found in southwestern Greenland, are "mixed migrators" and many individuals do not migrate; those that do migrate less than 60 km. Unlike the individual-tending mating system, aggregated rutting, synchronized calving and aggregated post-calving of barren-ground caribou, Greenland caribou have a harem-defense mating system and dispersed calving and they do not aggregate.

 

Although most wild tundra reindeer migrate between their winter range in taiga and summer range in tundra, some ecotypes or herds are more or less sedentary. Novaya Zemlya reindeer (R. t. pearsoni) formerly wintered on the mainland and migrated across the ice to the islands for summer, but only a few now migrate. Finnish forest reindeer (R. t. fennicus) were formerly distributed in most of the coniferous forest zones south of the tree line, including some mountains, but are now spottily distributed within this zone.

 

As an adaptation to their Arctic environment, they have lost their circadian rhythm.

 

Distribution and habitat

Originally, the reindeer was found in Scandinavia, Eastern Europe, Greenland, Russia, Mongolia and northern China north of the 50th latitude. In North America, it was found in Canada, Alaska, and the northern contiguous United States from Maine to Washington. In the 19th century, it was still present in southern Idaho. Even in historical times, it probably occurred naturally in Ireland, and it is believed to have lived in Scotland until the 12th century, when the last reindeer were hunted in Orkney. During the Late Pleistocene Epoch, reindeer occurred further south in North America, such as in Nevada, Tennessee, and Alabama, and as far south as Spain in Europe Today, wild reindeer have disappeared from these areas, especially from the southern parts, where it vanished almost everywhere. Large populations of wild reindeer are still found in Norway, Finland, Siberia, Greenland, Alaska and Canada.

 

According to Grubb (2005), Rangifer is "circumboreal in the tundra and taiga" from "Svalbard, Norway, Finland, Russia, Alaska (USA) and Canada including most Arctic islands, and Greenland, south to northern Mongolia, China (Inner Mongolia), Sakhalin Island, and USA (northern Idaho and Great Lakes region)." Reindeer were introduced to, and are feral in, "Iceland, Kerguelen Islands, South Georgia Island, Pribilof Islands, St. Matthew Island": a free-ranging semi-domesticated herd is also present in Scotland.

 

There is strong regional variation in Rangifer herd size. There are large population differences among individual herds and the size of individual herds has varied greatly since 1970. The largest of all herds (in Taimyr, Russia) has varied between 400,000 and 1,000,000; the second largest herd (at the George River in Canada) has varied between 28,000 and 385,000.

 

While Rangifer is a widespread and numerous genus in the northern Holarctic, being present in both tundra and taiga (boreal forest), by 2013, many herds had "unusually low numbers" and their winter ranges in particular were smaller than they used to be. Caribou and reindeer numbers have fluctuated historically, but many herds are in decline across their range. This global decline is linked to climate change for northern migratory herds and industrial disturbance of habitat for non-migratory herds. Barren-ground caribou are susceptible to the effects of climate change due to a mismatch in the phenological process between the availability of food during the calving period.

 

In November 2016, it was reported that more than 81,000 reindeer in Russia had died as a result of climate change. Longer autumns, leading to increased amounts of freezing rain, created a few inches of ice over lichen, causing many reindeer to starve to death.

 

Diet.

Reindeer are ruminants, having a four-chambered stomach. They mainly eat lichens in winter, especially reindeer lichen (Cladonia rangiferina); they are the only large mammal able to metabolize lichen owing to specialised bacteria and protozoa in their gut. They are also the only animals (except for some gastropods) in which the enzyme lichenase, which breaks down lichenin to glucose, has been found. However, they also eat the leaves of willows and birches, as well as sedges and grasses.

 

Reindeer are osteophagous; they are known to gnaw and partly consume shed antlers as a dietary supplement and in some extreme cases will cannibalise each other's antlers before shedding. There is also some evidence to suggest that on occasion, especially in the spring when they are nutritionally stressed, they will feed on small rodents (such as lemmings), fish (such as the Arctic char (Salvelinus alpinus)), and bird eggs. Reindeer herded by the Chukchis have been known to devour mushrooms enthusiastically in late summer.

 

During the Arctic summer, when there is continuous daylight, reindeer change their sleeping pattern from one synchronised with the sun to an ultradian pattern, in which they sleep when they need to digest food.

 

Predators.

A variety of predators prey heavily on reindeer, including overhunting by people in some areas, which contributes to the decline of populations.

 

Golden eagles prey on calves and are the most prolific hunter on the calving grounds. Wolverines will take newborn calves or birthing cows, as well as (less commonly) infirm adults.

 

Brown bears and polar bears prey on reindeer of all ages but, like wolverines, are most likely to attack weaker animals, such as calves and sick reindeer, since healthy adult reindeer can usually outpace a bear. The gray wolf is the most effective natural predator of adult reindeer and sometimes takes large numbers, especially during the winter. Some gray wolf packs, as well as individual grizzly bears in Canada, may follow and live off of a particular reindeer herd year-round.

 

In 2020, scientists on Svalbard witnessed, and were able to film for the first time, a polar bear attack reindeer, driving one into the ocean, where the polar bear caught up with and killed it. The same bear successfully repeated this hunting technique the next day. On Svalbard, reindeer remains account for 27.3% in polar bear scats, suggesting that they "may be a significant part of the polar bear's diet in that area".

 

Additionally, as carrion, reindeer may be scavenged opportunistically by red and Arctic foxes, various species of eagles, hawks and falcons, and common ravens.

 

Bloodsucking insects, such as mosquitoes, black flies, and especially the reindeer warble fly or reindeer botfly (Hypoderma tarandi) and the reindeer nose botfly (Cephenemyia trompe), are a plague to reindeer during the summer and can cause enough stress to inhibit feeding and calving behaviors. An adult reindeer will lose perhaps about 1 L (0.22 imp gal; 0.26 US gal) of blood to biting insects for every week it spends in the tundra. The population numbers of some of these predators is influenced by the migration of reindeer. Tormenting insects keep caribou on the move, searching for windy areas like hilltops and mountain ridges, rock reefs, lakeshore and forest openings, or snow patches that offer respite from the buzzing horde. Gathering in large herds is another strategy that caribou use to block insects.

 

Reindeer are good swimmers and, in one case, the entire body of a reindeer was found in the stomach of a Greenland shark (Somniosus microcephalus), a species found in the far North Atlantic.

 

Other threats

White-tailed deer (Odocoileus virginianus) commonly carry meningeal worm or brainworm (Parelaphostrongylus tenuis), a nematode parasite that causes reindeer, moose (Alces alces), elk (Cervus canadensis), and mule deer (Odocoileus hemionus) to develop fatal neurological symptoms which include a loss of fear of humans. White-tailed deer that carry this worm are partially immune to it.

 

Changes in climate and habitat beginning in the 20th century have expanded range overlap between white-tailed deer and caribou, increasing the frequency of infection within the reindeer population. This increase in infection is a concern for wildlife managers. Human activities, such as "clear-cutting forestry practices, forest fires, and the clearing for agriculture, roadways, railways, and power lines," favor the conversion of habitats into the preferred habitat of the white-tailed deer – "open forest interspersed with meadows, clearings, grasslands, and riparian flatlands." Towards the end of the Soviet Union, there was increasingly open admission from the Soviet government that reindeer numbers were being negatively affected by human activity, and that this must be remediated especially by supporting reindeer breeding by native herders.

 

Conservation

Current status

While overall widespread and numerous, some reindeer species and subspecies are rare and three subspecies have already become extinct. As of 2015, the IUCN has classified the reindeer as Vulnerable due to an observed population decline of 40% over the last +25 years. According to IUCN, Rangifer tarandus as a species is not endangered because of its overall large population and its widespread range.

 

In North America, the Queen Charlotte Islands caribou and the East Greenland caribou both became extinct in the early 20th century, the Peary caribou is designated as Endangered, the boreal woodland caribou is designated as Threatened and some individual populations are endangered as well. While the barren-ground caribou is not designated as Threatened, many individual herds — including some of the largest — are declining and there is much concern at the local level. Grant's caribou, a small, pale subspecies endemic to the western end of the Alaska Peninsula and the adjacent islands, has not been assessed as to its conservation status.

 

The status of the Dolphin-Union "herd" was upgraded to Endangered in 2017. In NWT, Dolphin-Union caribou were listed as Special Concern under the NWT Species at Risk (NWT) Act (2013).

 

Both the Selkirk Mountains caribou (Southern Mountain population DU9) and the Rocky Mountain caribou (Central Mountain population DU8) are classified as Endangered in Canada in regions such as southeastern British Columbia at the Canada–United States border, along the Columbia and Kootenay Rivers and around Kootenay Lake. Rocky Mountain caribou are extirpated from Banff National Park, but a small population remains in Jasper National Park and in mountain ranges to the northwest into British Columbia. Montane caribou are now considered extirpated in the contiguous United States, including Washington and Idaho. Osborn's caribou (Northern Mountain population DU7) is classified as Threatened in Canada.

 

In Eurasia, the Sakhalin reindeer is extinct (and has been replaced by domestic reindeer) and reindeer on most of the Novaya Zemlya islands have also been replaced by domestic reindeer, although some wild reindeer still persist on the northern islands. Many Siberian tundra reindeer herds have declined, some dangerously, but the Taymir herd remains strong and in total about 940,000 wild Siberian tundra reindeer were estimated in 2010.

 

There is strong regional variation in Rangifer herd size. By 2013, many caribou herds in North America had "unusually low numbers" and their winter ranges in particular were smaller than they used to be. Caribou numbers have fluctuated historically, but many herds are in decline across their range. There are many factors contributing to the decline in numbers.

 

Boreal woodland caribou

Ongoing human development of their habitat has caused populations of boreal woodland caribou to disappear from their original southern range. In particular, boreal woodland caribou were extirpated in many areas of eastern North America in the beginning of the 20th century.

"I only lost one feet, not losing my spirit!" - The Brave Rock Pigeon or Rock Dove (Columba livia)

 

Rock Pigeon or Rock Dove (Columba livia)

 

The rock dove (Columba livia) or rock pigeon is a member of the bird family Columbidae (doves and pigeons). In common usage, this bird is often simply referred to as the "pigeon".

 

The species includes the domestic pigeon (including the fancy pigeon), and escaped domestic pigeons have given rise to feral populations around the world.

 

Wild rock doves are pale grey with two black bars on each wing, while domestic and feral pigeons are very variable in colour and pattern. There are few visible differences between males and females. The species is generally monogamous, with two squabs (young) per brood. Both parents care for the young for a time.

 

Habitats include various open and semi-open environments. Cliffs and rock ledges are used for roosting and breeding in the wild. Originally found wild in Europe, North Africa, and western Asia, feral pigeons have become established in cities around the world. The species is abundant, with an estimated population of 17 to 28 million feral and wild birds in Europe.

  

Taxonomy and naming

 

The rock dove was first described by Gmelin in 1789.[8] The genus name Columba is the Latin word meaning "pigeon, dove", whose older etymology comes from the Ancient Greek κόλυμβος (kolumbos), "a diver", from κολυμβάω (kolumbao), "dive, plunge headlong, swim". Aristophanes (Birds, 304) and others use the word κολυμβίς (kolumbis), "diver", for the name of the bird, because of its swimming motion in the air. The specific epithet is derived from the Latin livor, "bluish". Its closest relative in the Columba genus is the hill pigeon, followed by the other rock pigeons: the snow, speckled and white-collared pigeons.

 

The species is also known as the rock pigeon or blue rock dove, the former being the official name from 2004 to 2011, at which point the IOC changed their official listing to its original British name of rock dove (styled as Rock Dove). In common usage, this bird is still often simply referred to as the "pigeon". Pigeon chicks are called squabs.

  

Subspecies[edit]

 

There are 12 subspecies recognised by Gibbs (2000); some of these may be derived from feral stock.

 

- C. l. livia, the nominate subspecies, occurs in western and southern Europe, northern Africa, and Asia to western Kazakhstan, the northern Caucasus, Georgia, Cyprus, Turkey, Iran, and Iraq.

 

- C. l. atlantis (Bannerman, 1931) of Madeira, the Azores and Cape Verde, is a very variable population with chequered upperparts obscuring the black wingbars, and is almost certainly derived from feral pigeons.

 

- C. l. canariensis (Bannerman, 1914) of the Canary Islands, is smaller and averages darker than the nominate subspecies.

 

- C. l. gymnocyclus (Gray, 1856) from Senegal and Guinea to Ghana, Benin and Nigeria is smaller and very much darker than nominate C. l. livia. It is almost blackish on the head, rump and underparts with a white back and the iridescence of the nape extending onto the head.

 

- C. l. targia (Geyr von Schweppenburg, 1916) breeds in the mountains of the Sahara east to Sudan. It is slightly smaller than the nominate form, with similar plumage, but the back is concolorous with the mantle instead of white.

 

- C. l. dakhlae (Richard Meinertzhagen, 1928) is confined to the two oases in central Egypt. It is smaller and much paler than the nominate subspecies.

 

- C. l. schimperi (Bonaparte, 1854) is found in the Nile Delta south to northern Sudan. It closely resembles C. l. targia, but has a distinctly paler mantle.

 

- C. l. palaestinae (Zedlitz, 1912) occurs from Syria to Sinai and Arabia. It is slightly larger than C. l. schimperi and has darker plumage.

 

- C. l. gaddi (Zarodney & Looudoni, 1906), breeds from Azerbaijan and Iran east to Uzbekistan is larger and paler than C. l. palaestinae with which it intergrades in the west. It also intergrades with the next subspecies to the east.

 

- C. l. neglecta (Hume, 1873), is found in the mountains of eastern Central Asia. It is similar to the nominate subspecies in size, but is darker with a stronger and more extensive iridescent sheen on the neck. It intergrades with the next race in the south.

 

- C. l. intermedia (Strickland, 1844) occurs in Sri Lanka and in India south of the Himalayan range of C. l. neglecta. It is similar to that subspecies, but darker with a less contrasting back.

 

- C. l. nigricans (Buturlin, 1908) in Mongolia and north China is variable and probably derived from feral stock.

  

Description

 

The adult of the nominate subspecies of the rock dove is 29 to 37 cm (11 to 15 in) long with a 62 to 72 cm (24 to 28 in) wingspan. Weight for wild or feral rock doves ranges from 238–380 g (8.4–13.4 oz), though overfed domestic and semi-domestic individuals can exceed normal weights. It has a dark bluish-gray head, neck, and chest with glossy yellowish, greenish, and reddish-purple iridescence along its neck and wing feathers. The iris is orange, red or golden with a paler inner ring, and the bare skin round the eye is bluish-grey. The bill is grey-black with a conspicuous off-white cere, and the feet are purplish-red. Among standard measurements, the wing chord is typically around 22.3 cm (8.8 in), the tail is 9.5 to 11 cm (3.7 to 4.3 in), the bill is around 1.8 cm (0.71 in) and the tarsus is 2.6 to 3.5 cm (1.0 to 1.4 in).

 

The adult female is almost identical to the male, but the iridescence on the neck is less intense and more restricted to the rear and sides, while that on the breast is often very obscure.

 

The white lower back of the pure rock dove is its best identification character; the two black bars on its pale grey wings are also distinctive. The tail has a black band on the end and the outer web of the tail feathers are margined with white. It is strong and quick on the wing, dashing out from sea caves, flying low over the water, its lighter grey rump showing well from above.

 

Young birds show little lustre and are duller. Eye colour of the pigeon is generally orange but a few pigeons may have white-grey eyes. The eyelids are orange in colour and are encapsulated in a grey-white eye ring. The feet are red to pink.

 

When circling overhead, the white underwing of the bird becomes conspicuous. In its flight, behaviour, and voice, which is more of a dovecot coo than the phrase of the wood pigeon, it is a typical pigeon. Although it is a relatively strong flier, it also glides frequently, holding its wings in a very pronounced V shape as it does. Though fields are visited for grain and green food, it is often not plentiful enough as to be a viewed as pest.

 

Pigeons feed on the ground in flocks or individually. They roost together in buildings or on walls or statues. When drinking, most birds take small sips and tilt their heads backwards to swallow the water. Pigeons are able to dip their bills into the water and drink continuously without having to tilt their heads back. When disturbed, a pigeon in a group will take off with a noisy clapping sound.

 

Pigeons, especially homing or carrier breeds, are well known for their ability to find their way home from long distances. Despite these demonstrated abilities, wild rock doves are sedentary and rarely leave their local areas.

  

Distribution and habitat

 

The rock dove has a restricted natural resident range in western and southern Europe, North Africa, and into South Asia. The rock dove is often found in pairs in the breeding season but is usually gregarious. The species (including ferals) has a large range, with an estimated global extent of occurrence of 10,000,000 km2 (3,900,000 sq mi). It has a large global population, including an estimated 17–28 million individuals in Europe. Fossil evidence suggests the rock dove originated in southern Asia and skeletal remains unearthed in Israel confirm their existence there for at least three hundred thousand years. However, this species has such a long history with humans that it is impossible to tell exactly where the species' original range was. Its habitat is natural cliffs, usually on coasts. Its domesticated form, the feral pigeon, has been widely introduced elsewhere, and is common, especially in cities, over much of the world. A rock pigeon's lifespan is anywhere from 3–5 years in the wild to 15 years in captivity, though longer-lived specimens have been reported. The main causes of mortality in the wild are predators and persecution by humans. The species was first introduced to North America in 1606 at Port Royal, Nova Scotia.

  

Reproduction

 

The rock dove breeds at any time of the year, but peak times are spring and summer. Nesting sites are along coastal cliff faces, as well as the artificial cliff faces created by apartment buildings with accessible ledges or roof spaces.

 

The nest is a flimsy platform of straw and sticks, laid on a ledge, under cover, often on the window ledges of buildings. Two white eggs are laid; incubation is shared by both parents lasting from seventeen to nineteen days. The newly hatched squab (nestling) has pale yellow down and a flesh-coloured bill with a dark band. For the first few days, the baby squab is tended and fed (through regurgitation) exclusively on "crop milk" (also called "pigeon milk" or "pigeon's milk"). The pigeon milk is produced in the crops of both parents in all species of pigeons and doves. The fledging period is about 30 days.

  

Predators

 

With only its flying abilities protecting it from predation, rock pigeons are a favorite almost around the world for a wide range of raptorial birds. In fact, with feral pigeons existing in almost every city in the world, they may form the majority of prey for several raptor species who live in urban areas. Peregrine falcons and Eurasian sparrowhawks are natural predators of pigeons that are quite adept at catching and feeding upon this species. Up to 80% of the diet of peregrine falcons in several cities that have breeding falcons is composed of feral pigeons. Some common predators of feral pigeons in North America are opossums, raccoons, red-tailed hawks, great horned owls, eastern screech owls and Accipiters. The birds that predate pigeons in North America can range in size from American kestrels to golden eagles and can even include gulls, crows, and ravens. On the ground the adults, their young and their eggs are at risk from feral and domestic cats. Doves and pigeons are considered to be game birds as many species have been hunted and used for food in many of the countries in which they are native.

  

Parasites

 

Pigeons may harbour a diverse parasite fauna. They often host the intestinal helminths Capillaria columbae and Ascaridia columbae. Their ectoparasites include the Ischnoceran lice Columbicola columbae, Campanulotes bidentatus compar, the Amblyceran lice Bonomiella columbae, Hohorstiella lata, Colpocephalum turbinatum, the mites Tinaminyssus melloi, Dermanyssus gallinae, Dermoglyphus columbae, Falculifer rostratus, and Diplaegidia columbae. The hippoboscid fly Pseudolynchia canariensis is a typical blood-sucking ectoparasite of pigeons, found only in tropical and sub-tropical regions.

  

Human health

 

Pigeons have been falsely associated with the spread of human diseases. Contact with pigeon droppings poses a minor risk of contracting histoplasmosis, cryptococcosis, and psittacosis, and exposure to both droppings and feathers can produce bird fancier's lung. Pigeons are not a major concern in the spread of West Nile virus; though they can contract it, they do not appear to be able to transmit it. Pigeons are, however, at potential risk for carrying and spreading avian influenza. One study has shown that adult pigeons are not clinically susceptible to the most dangerous strain of avian influenza, the H5N1, and that they did not transmit the virus to chickens. Other studies have presented evidence of clinical signs and neurological lesions resulting from infection, but found that the pigeons did not transmit the disease to chickens reared in direct contact with them. Pigeons were found to be "resistant or minimally susceptible" to other strains of avian influenza, such as the H7N7.

  

Domestication

 

Rock doves have been domesticated for several thousand years, giving rise to the domestic pigeon (Columba livia domestica). As well as food and pets, domesticated pigeons are used as homing pigeons. They were in the past also used as carrier pigeons, and so-called war pigeons have played significant roles during wartime, with many pigeons having received bravery awards and medals for their services in saving hundreds of human lives: including, notably, the British pigeon Cher Ami who received the Croix de Guerre for her heroic actions during World War I, and the Irish Paddy and the American G.I. Joe, who both received the Dickin Medal, amongst 32 pigeons to receive this medallion, for their gallant and brave actions during World War II. There are numerous breeds of fancy pigeons of all sizes, colours and types.

  

Feral pigeon

 

Many domestic birds have escaped or been released over the years, and have given rise to the feral pigeon. These show a variety of plumages, although some have the blue barred pattern as does the pure rock dove. Feral pigeons are found in large numbers in cities and towns all over the world. The scarcity of the pure wild species is partly due to interbreeding with feral birds.

  

Osmoregulation

 

Challenges

 

Water is taken in by the Columba livia directly by drinking water or indirectly from the food they ingest. They drink water through a process called double-suction mechanism. The daily diet of the Pigeon places many physiologically challenges it must over come through osmoregulation. Protein intake for example causes an excess toxins of amine groups when it is broken down for energy. To regulate this excess and secrete these unwanted toxins the Columba livia must remove the amine groups as uric acid. Nitrogen excretion through uric acid can be considered an advantage because it doesn't require a lot of water and isn't very soluble, but producing it takes more energy because of its complex molecular composition.

 

The danger of desiccation is a major threat to animals living on land. Water is lost in urine and feces, but evaporation is the principal route of water loss. Water lost must be replaced by drinking and water in food. Dehydration or salt-loading decreases the filtration rate primarily by the shut down of the nephrons, which is controlled by an antidiuretic hormone, arginine vasotocin. Pigeons adjust their drinking rates and food intake in parallel and when adequate water is unavailable for excretion, food intake is limited to maintain water balance. As Columbia livia inhabit arid environments, research attributes this to their strong flying capabilities to reach the available water sources, not because of exceptional potential for water conservation. Columba livia kidneys, like mammalian kidneys, are capable of producing urine hyperosmotic to the plasma utilizing the processes of filtration, reabsorption and secretion, which will be discussed later and explained through the Starling-Landis Hypothesis. The medullary cones function as countercurrent units that achieve the production of hyperosmotic urine. Hyperosmotic urine can be understood in light of the law of diffusion and osmolarity.

 

Organ of osmoregulation

 

Unlike a number other bird species which have the salt gland as the primary osmoregulatory organ, Columba livia does not use their salt gland even though it exists. Columba livia uses the function of their kidneys to maintain homeostatic balance of ions such as sodium and potassium while preserving water quantity in the body. Filtration of the blood, reabsorption of ions and water, and secretion of uric acid are all components of the kidney's process. The kidneys of Columba livia are located in its pelvic region. Columba livia has two kidneys that are coupled, each having three partially separate lobes; the posterior lobe is the largest in size. Like mammalian kidneys, the avian kidney contains a medullary region and a cortical region. Peripherally located around the cortical region, the collecting ducts gather into cone-like ducts, medullary cones, which converge into the ureters. There are two types of nephrons in the kidney; nephrons that are located in the cortex and do not contain the loop of Henle are called loopless nephrons, the other type are called looped or mammalian nephrons. Looped nephrons contain the loop of Henle that continue down into the medulla then enter the distal tubule drain towards the ureter. Mammals generally have a more vascularized glomeruli than the nephrons in birds. The nephrons of avian species can not produce urine that is hyperosmotic to the blood, but, the loop of Henle utilizes countercurrent multiplication which allows it to become hyperosmotic in the collecting duct. This alternation of permeability between different sections of the ascending and descending loop allows for the elevation of the urine osmotic pressure 2.5 times above the blood osmotic pressure.

  

Specialize cell types involved in osmoregulation

 

The integumentary system functions in osmoregulation by acting as a barrier between the extracellular compartment and the environment to regulate water gain and loss, as well as solute flux. The permeability of the integument to water and solutes varies from animal to animal.The excretory system is responsible for regulating water and solute levels in the body fluids. Pigeons can produce hyperosmotic urine but their renal system is different from other animals. They do not produce concentrated urine to reduce water loss but produce a whitish part called urate. It is considered as uric acid solid crystals and it is less toxic than urea. The wastes move from the blood of the peritubular capillaries passes through the tubule cells and into the collecting ducts and transported as urate (uric acid). Urate is then transported to the cloaca and from there to the large intestine where uric acid particle and water and solutes in the urine can be reabsorbed and balanced. Thus this allows them to save their body water instead of excreting large volume of dilute urea. Cells of the proximal tubule have numerous microvilli and mitochondria which provide surface area and energy to the proximal tubule cells.

 

The blood pH is regulated by the A and B types of cells located in distal tubule and collecting duct. The A type cells are acid secreting cells that have a proton ATPase in the apical membrane and a Cl-/ HCO3- exchange system in the basolateral membrane whereas, the B type cells are base secreting cells, which secrete bicarbonate into the lumen of the tubule in exchange for chloride ions. The regulation of pH in blood determines whether bicarbonate is reabsorbed or secreted.

 

Transport mechanisms of osmoregulation

 

The filtrate contains lots of important substances. In the proximal tubules of the Columbia livia kidney, substances that are needed, such as vitamins and glucose are reabsorbed into the blood. Their kidney has a variety of ion channels involved in salt and water transport. Water is reabsorbed through aquaporins which are present in the lumen of proximal tubule, basolateral membrane, and blood vessel near proximal tubule. Water flows from the epithelial cells into the blood via osmosis. Since osmosis occurs, the osmolarity of the filtrate remains isotonic. Sodium/Potassium/ATPase transporter is located in the basolateral membrane of the epithelial cell, which is opposite of the lumen of proximal tubule, and actively pumps sodium out of the cell into the blood.

  

Special adaptations

 

Eggshell's gas exchange and water loss

 

Gas exchange across eggshells results in water loss from the egg. However, the egg must retain enough water to hydrate the embryo. This results in the knowledge that changing temperatures and humidity can affect the eggshell's architecture. Behavioral adaptations in Columba livia and other birds, such as the incubation of their eggs, can help with the effects of these changing environments. It was found that eggshell architecture undergoes selection decoupled from behavioral effects, and that humidity may be a driving selective pressure. Low humidity requires enough water to keep the embryo from desiccation, and high humidity needs enough water loss to facilitate the initiation of pulmonary respiration. The water loss from the eggshell is directly linked to the growth rate of the species. The ability of the embryo to tolerate extreme water loss is due to the parental behavior in species colonizing in different environments. Studies have been done showing that wild habitats of Columba livia and other birds have a higher rate tolerance of various humidity levels, but Columba livia do prefer areas where the humidity closely matched their native breeding conditions. The pore areas of the shells allow water to diffuse in and out of the shell, preventing the possible harming of the embryo due to the high rates of water retention. If an eggshell is thinner, it can cause a decrease in pore length, and an increase in conductance and pore area. A thinner eggshell can also cause a decrease in mechanical restriction of the embryo.

  

Thermoregulation

 

Temperature changes

 

The Columbia Livia is habituated within many vast environments with varying degrees of temperatures. Like all vertebrates, Columbia Livia perspires heat through evaporation of water when temperatures are high in the environment. It’s preferred niche temperature ranges between +39 - +42 degrees Celsius.

 

Peripheral thermoreceptors of the Columbia Liva regulate its body’s response to the cold. During low temperatures, which put the Columbia Liva’s body under stress it accommodates extreme temperatures by increasing its internal temperatures within the core and spinal cord. Along with this increase, there is also a decrease in temperature within the legs, neck and back skin.

 

Physiological challenges placed on organism

 

Columba Livia stabilize their internal body temperature independent of alteration in ambient temperature. They are also able to withstand extreme climate conditions, such as ambient temperature range of +42 to -40 °C. The temperature regulation of Columba Livia is generally based on the principle of endotherms. Being endothermic they use metabolic heat to raise body temperature. Columba Livia are also homeotherms, meaning that they are thermoregulators and maintain a relatively constant body temperature. The heat exchange between animals and their surroundings occurs due to conduction, convection, radiation and evaporation. Fourier's Law of Heat Conduction describes the loss of heat experienced by animals through conduction. At low ambient temperatures the endothermic animals are able to reduce their heat loss by lowering the skin temperature and by increasing their peripheral insulation, which is discussed later.

 

Behavioral adaptations

 

Columba Livia does a few things to regulate its body temperature. Normally it will drink water after they have eaten, but when stressed by heat they can drink whenever needed to lower its body temperature. Another way it can regulate its heat is through Ptilomotor responses. Ptilomotor responses allow for better insulation of the body, because smooth muscle contractions make the feathers stand up straighter, which traps more air next to the skin. Columba Livia exhibits Ta (ambient temperature) selecting behavior. It will seek out its desired thermal neutral zone temperatures, in order to expend less energy heating and cooling its body.

 

Physiological changes to blood flow

 

Areas poorly or not insulated by feathers such as the beak, head, and feet have vasomotor responses. To reduce heat loss while in cold atmospheric temperatures, endothermic animals will lower the skin temperature by restricting the amount of blood that reaches it, called vasoconstriction. The sympathetic nervous system stimulates the constriction of the vascular beds at low temperatures. Vasodilation does the opposite; to increase the heat lost by convection after high muscular activity or from heat stress, Columba Livia increases its blood flow to the surface of its body. Cutaneous tissue of the beak, feet, and bends in the wings are dilated. To regulate brain temperature it uses the vascular vessels(plexus) in the eyes, in combination with vasomotion. Evaporation is usually controlled by sweat glands, however, birds use their breathing pattern to control heat dissipation. The frequency in breathing depends on body temperature, Tb; to increase respiratory evaporation the bird's breathing rate would increase. The most important thermoregulatory mechanism is called shivering thermogenesis. The skeletal muscles are used to generate heat through contractions when the surrounding air, Ta, is below its thermal neutral zone. As the temperature drops, the shivering increases to generate more heat. Non-shivering thermogenesis is used by Columba Livia, when exposed to cold to generate heat; an increase in Na+/K+-ATPase activity drives this mechanism in the liver.

 

Special adaptations

 

A study was done by Michael E. Rashotte, et al. (1998) comparing the vigilance states and body temperature is different within in fed and fasted pigeons (Columba Livia). Fasting induces nocturnal hypothermia in pigeons. There are different sleep patterns associated with heat production in pigeons, slow wave sleep (SWS) and paradoxical sleep (PS). An increase of SWS and PS was compared to the fasting-induced nocturnal hypothermia by comparing body temperature (Tb) and vigilance states when pigeons were fed and fasted. It was found that the Tb was decreasing near the beginning of the dark phase and that the time spent in SWS and PS was elevated in the fasting pigeons due to the increase of frequency and duration. When body temperature was low in the middle of the dark phase, it showed that SWS was elevated but it did not affect the PS stage. When the body temperature was high during the last hours of dark, SWS remained elevated in fasting-induced and that PS was relatively high. Rashotte, et al. (1998) suggests that more evidence is needed to confirm these results but he suggests that pigeons may be best viewed as an animal that has a shallow hypometabolic state that fall within (or very close to) their euthermic range. It is also seen that a pigeon’s vigilance stage can be compared similarly to mammals in hibernation.

 

Specialized organs or anatomy involved in thermoregulation

 

The purpose of thermoregulation is to maintain body temperature by producing heat through physiological and metabolic reactions. Heat gain should equal to rates of heat loss. If the body temperature is unbalanced, the animal becomes either warmer or colder. Heat production in birds is associated to shivering. The large flight muscles- pectoralis as well as the leg muscles generate heat by shivering.

 

Columba Livia have strong wings with flexible feathers which provide enough insulation to keep their body warm and dry. The fat layers and feathers reduce the flow of heat between an animal and its environment and lower the energy cost of keeping warm. In some birds the heat loss from the legs and feet is limited in cold weather because of a countercurrent mechanism that saves heat and in hot weather it can serve as heat radiators which increase blood flow.

 

Thermoregulation in birds requires cooling as well as warming. At low temperature birds can tuck head and neck under their wings to reduce heat loss. The heat is lost by the pigeons as an insensible heat by evaporation of water from the respiratory system and skin when temperature gradient is less and relative humidity is low. At the relatively high temperature birds increase their respiration rate to increase their cooling by evaporation. The panting is important in birds which involves gular flutter. The pouch richly supplied with blood vessels in the floor of the mouth; the rapid movement of the upper throat tissues - fluttering the pouch increases evaporation. Pigeons can use evaporative cooling to keep body temperature close to 40 °C in air temperatures as high as 60 °C, as long as they have sufficient water.

 

Also from previous studies experiment shows that a bird is capable of evaporating enough water from the cloaca for thermoregulation and results suggests that some birds’ cloacal evaporation can be controlled and could serve as an important maneuver for thermoregulation at high ambient temperatures.

 

Regulation of metabolism

 

Columba livia as homeothermic animals, are able to regulate heat production and external heat loss in autonomic ways, by a feedback control system. Negative feedback is the most important principle for regulation; a decrease of ambient temperature evoked by cold activates some thermoregulatory effector mechanisms, which reduce the heat loss and increase the internal heat production. The metabolic rate of resting Columba Livia at neutral ambient temperature, is reduced by a level of 5-10% during drowsiness, sleep and darkness. An increase follows every kind of muscle activity, such as flying, which increases metabolic rate by 10-12 times. Heat production throughout the day contributes to a high level of body temperature.

 

[Credit: en.wikipedia.org/]

Les capillaires sanguins du rete mirabile sont innombrables et intimement associés les uns par rapport aux autres. Une telle structure est de ce fait quasi dépourvue de tout tissu conjonctif. Capillaires artériels et veineux ne sont pas différenciables sur ce genre de préparation. La disposition des capillaires et l’abondance des cellules sanguines (cercles autour des globules rouges) fournissent une image particulièrement étonnante !

 

- Pour plus de détails ou précisions, voir « Atlas of Fish Histology » CRC Press, ou « Histologie illustrée du poisson » (QUAE) ou s'adresser à Franck Genten (fgenten@gmail.com)

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The blood capillaries in the rete mirabile are numerous

and so closely arranged that they leave no interspaces for any connective tissue. Arterial and venous capillaries are not distinguishable on this light microscopy preparation. The pattern of arrangement of the blood capillaries in this mass and the abundance of blood cells (circles around the red blood cells) give a fascinating appearance in this longitudinal section.

 

- For more information or details, see « Atlas of Fish Histology » CRC Press, or « Histologie illustrée du poisson » (QUAE) or contact Franck Genten (fgenten@gmail.com)

 

Agrandissement d'une partie de l'image P8a_007. Le rete mirabile est une structure complexe extraordinaire qui consiste en un réseau de capillaires disposés à contre-courant entre les sangs entrant et sortant de l'organe. C'est donc une vaste surface d’échanges gazeux (cas présent), thermiques (musculature chez les thons et certaines espèces de requins) ou ioniques.

 

- Pour plus de détails ou précisions, voir « Atlas of Fish Histology » CRC Press, ou « Histologie illustrée du poisson » (QUAE) ou s'adresser à Franck Genten (fgenten@gmail.com)

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Magnification of a portion of picture P8a_007. The rete

mirabile is a wonderful complex structure consisting of a countercurrent arrangement of arterial and venous capillaries which do not communicate until they reach the gas gland. Countercurrent mechanism maximizes the rate of exchange by possessing two fluid systems separated by a permeable membrane across which exchange of gases (like here), heat (muscles of tunas and some sharks) or ions can occur.

 

- For more information or details, see « Atlas of Fish Histology » CRC Press, or « Histologie illustrée du poisson » (QUAE) or contact Franck Genten (fgenten@gmail.com)

 

Bundoora Arabesque (about 1.3 metres x 2.9 metres) is painted on doubly primed canvas in acrylic. The underlying scaffolding geometry is a Mediaeval Muslim tile art pattern upon which is superimposed a classical Renaissance Italian double Golden Rectangle between upper and lower border strips as in Pablo Picasso's "Guernica" . The painting is an abstract expressionist view of Bundoora (the Land that Kangaroos Love in the local Indigenous Australian Wurrundjeri language) where La Trobe University is located. Spot the numerous kangaroos and other wildlife hiding in the bush!

 

For detailed discussion of "Bundoora Arabesque" see Gideon Polya , “La Trobe University, “Bundoora Arabesque” And Australian Aboriginal Genocide” Countercurrents, 12 August, 2007: sites.google.com/site/aboriginalgenocide/-bundoora-arabes... and www.countercurrents.org/polya120807.htm and "Bundoora Arabesque": sites.google.com/site/artforpeaceplanetmotherchild/bundoo... .

 

Australian Aborigines suffered Genocide at the hands of the European invaders in the 19th and 20th centuries. The Indigenous population dropped from about 1 million to 0.1 million in the first century after the invasion in 1788, mainly through violence, dispossession, deprivation and introduced disease. The last massacres of Aborigines occurred in the 1920s. Throughout much of the 20th century there was a policy of forcibly removing Aboriginal children from their mothers, a systematic genocidal policy involving the removal of perhaps 0.1 million children. This practice ended in the 1970s. However the continued deliberate deprivation of Aboriginal Australians amounts to a White Australian policy of passive genocide.

 

The “annual death rate” (2003 figures) is 2.2% (for Aboriginal Australians) and 2.4% (for Aboriginal Australians in the Northern Territory) – as compared to 2.5% (for pre-drought sheep in paddocks of Australian sheep farms) and 0.7% (for White Australians). This is happening in one of the richest countries of the world because of deliberate neglect – Australian Aboriginal health services are funded at 50% of what they should be; many Australian Aborigines live in Third World conditions; the “annual under-5 infant death rate” is over 3 times higher for Aborigines than that for White Australians; 1 in 5 Australian Aborigines have diabetes (mostly type 2 diabetes) which has huge attendant problems such as cardiovascular complications, kidney problems and blindness; and the Australian Aboriginal life expectancy is about 20 years less than that for White Australians.

 

About 9,000 Indigenous Australians die avoidably each year out of a population of 0.5 million (see "Aboriginal Genocide": sites.google.com/site/aboriginalgenocide/home ).

Immatured Rock Pigeon or Rock Dove (Columba livia)

  

The rock dove (Columba livia) or rock pigeon is a member of the bird family Columbidae (doves and pigeons). In common usage, this bird is often simply referred to as the "pigeon".

  

The species includes the domestic pigeon (including the fancy pigeon), and escaped domestic pigeons have given rise to feral populations around the world.

  

Wild rock doves are pale grey with two black bars on each wing, while domestic and feral pigeons are very variable in colour and pattern. There are few visible differences between males and females. The species is generally monogamous, with two squabs (young) per brood. Both parents care for the young for a time.

  

Habitats include various open and semi-open environments. Cliffs and rock ledges are used for roosting and breeding in the wild. Originally found wild in Europe, North Africa, and western Asia, feral pigeons have become established in cities around the world. The species is abundant, with an estimated population of 17 to 28 million feral and wild birds in Europe.

  

Taxonomy and naming

  

The rock dove was first described by Gmelin in 1789.[8] The genus name Columba is the Latin word meaning "pigeon, dove", whose older etymology comes from the Ancient Greek κόλυμβος (kolumbos), "a diver", from κολυμβάω (kolumbao), "dive, plunge headlong, swim". Aristophanes (Birds, 304) and others use the word κολυμβίς (kolumbis), "diver", for the name of the bird, because of its swimming motion in the air. The specific epithet is derived from the Latin livor, "bluish". Its closest relative in the Columba genus is the hill pigeon, followed by the other rock pigeons: the snow, speckled and white-collared pigeons.

  

The species is also known as the rock pigeon or blue rock dove, the former being the official name from 2004 to 2011, at which point the IOC changed their official listing to its original British name of rock dove (styled as Rock Dove). In common usage, this bird is still often simply referred to as the "pigeon". Pigeon chicks are called squabs.

  

Subspecies[edit]

  

There are 12 subspecies recognised by Gibbs (2000); some of these may be derived from feral stock.

  

- C. l. livia, the nominate subspecies, occurs in western and southern Europe, northern Africa, and Asia to western Kazakhstan, the northern Caucasus, Georgia, Cyprus, Turkey, Iran, and Iraq.

  

- C. l. atlantis (Bannerman, 1931) of Madeira, the Azores and Cape Verde, is a very variable population with chequered upperparts obscuring the black wingbars, and is almost certainly derived from feral pigeons.

  

- C. l. canariensis (Bannerman, 1914) of the Canary Islands, is smaller and averages darker than the nominate subspecies.

  

- C. l. gymnocyclus (Gray, 1856) from Senegal and Guinea to Ghana, Benin and Nigeria is smaller and very much darker than nominate C. l. livia. It is almost blackish on the head, rump and underparts with a white back and the iridescence of the nape extending onto the head.

  

- C. l. targia (Geyr von Schweppenburg, 1916) breeds in the mountains of the Sahara east to Sudan. It is slightly smaller than the nominate form, with similar plumage, but the back is concolorous with the mantle instead of white.

  

- C. l. dakhlae (Richard Meinertzhagen, 1928) is confined to the two oases in central Egypt. It is smaller and much paler than the nominate subspecies.

  

- C. l. schimperi (Bonaparte, 1854) is found in the Nile Delta south to northern Sudan. It closely resembles C. l. targia, but has a distinctly paler mantle.

  

- C. l. palaestinae (Zedlitz, 1912) occurs from Syria to Sinai and Arabia. It is slightly larger than C. l. schimperi and has darker plumage.

  

- C. l. gaddi (Zarodney & Looudoni, 1906), breeds from Azerbaijan and Iran east to Uzbekistan is larger and paler than C. l. palaestinae with which it intergrades in the west. It also intergrades with the next subspecies to the east.

  

- C. l. neglecta (Hume, 1873), is found in the mountains of eastern Central Asia. It is similar to the nominate subspecies in size, but is darker with a stronger and more extensive iridescent sheen on the neck. It intergrades with the next race in the south.

  

- C. l. intermedia (Strickland, 1844) occurs in Sri Lanka and in India south of the Himalayan range of C. l. neglecta. It is similar to that subspecies, but darker with a less contrasting back.

  

- C. l. nigricans (Buturlin, 1908) in Mongolia and north China is variable and probably derived from feral stock.

  

Description

  

The adult of the nominate subspecies of the rock dove is 29 to 37 cm (11 to 15 in) long with a 62 to 72 cm (24 to 28 in) wingspan. Weight for wild or feral rock doves ranges from 238–380 g (8.4–13.4 oz), though overfed domestic and semi-domestic individuals can exceed normal weights. It has a dark bluish-gray head, neck, and chest with glossy yellowish, greenish, and reddish-purple iridescence along its neck and wing feathers. The iris is orange, red or golden with a paler inner ring, and the bare skin round the eye is bluish-grey. The bill is grey-black with a conspicuous off-white cere, and the feet are purplish-red. Among standard measurements, the wing chord is typically around 22.3 cm (8.8 in), the tail is 9.5 to 11 cm (3.7 to 4.3 in), the bill is around 1.8 cm (0.71 in) and the tarsus is 2.6 to 3.5 cm (1.0 to 1.4 in).

  

The adult female is almost identical to the male, but the iridescence on the neck is less intense and more restricted to the rear and sides, while that on the breast is often very obscure.

  

The white lower back of the pure rock dove is its best identification character; the two black bars on its pale grey wings are also distinctive. The tail has a black band on the end and the outer web of the tail feathers are margined with white. It is strong and quick on the wing, dashing out from sea caves, flying low over the water, its lighter grey rump showing well from above.

  

Young birds show little lustre and are duller. Eye colour of the pigeon is generally orange but a few pigeons may have white-grey eyes. The eyelids are orange in colour and are encapsulated in a grey-white eye ring. The feet are red to pink.

  

When circling overhead, the white underwing of the bird becomes conspicuous. In its flight, behaviour, and voice, which is more of a dovecot coo than the phrase of the wood pigeon, it is a typical pigeon. Although it is a relatively strong flier, it also glides frequently, holding its wings in a very pronounced V shape as it does. Though fields are visited for grain and green food, it is often not plentiful enough as to be a viewed as pest.

  

Pigeons feed on the ground in flocks or individually. They roost together in buildings or on walls or statues. When drinking, most birds take small sips and tilt their heads backwards to swallow the water. Pigeons are able to dip their bills into the water and drink continuously without having to tilt their heads back. When disturbed, a pigeon in a group will take off with a noisy clapping sound.

  

Pigeons, especially homing or carrier breeds, are well known for their ability to find their way home from long distances. Despite these demonstrated abilities, wild rock doves are sedentary and rarely leave their local areas.

  

Distribution and habitat

  

The rock dove has a restricted natural resident range in western and southern Europe, North Africa, and into South Asia. The rock dove is often found in pairs in the breeding season but is usually gregarious. The species (including ferals) has a large range, with an estimated global extent of occurrence of 10,000,000 km2 (3,900,000 sq mi). It has a large global population, including an estimated 17–28 million individuals in Europe. Fossil evidence suggests the rock dove originated in southern Asia and skeletal remains unearthed in Israel confirm their existence there for at least three hundred thousand years. However, this species has such a long history with humans that it is impossible to tell exactly where the species' original range was. Its habitat is natural cliffs, usually on coasts. Its domesticated form, the feral pigeon, has been widely introduced elsewhere, and is common, especially in cities, over much of the world. A rock pigeon's lifespan is anywhere from 3–5 years in the wild to 15 years in captivity, though longer-lived specimens have been reported. The main causes of mortality in the wild are predators and persecution by humans. The species was first introduced to North America in 1606 at Port Royal, Nova Scotia.

  

Reproduction

  

The rock dove breeds at any time of the year, but peak times are spring and summer. Nesting sites are along coastal cliff faces, as well as the artificial cliff faces created by apartment buildings with accessible ledges or roof spaces.

  

The nest is a flimsy platform of straw and sticks, laid on a ledge, under cover, often on the window ledges of buildings. Two white eggs are laid; incubation is shared by both parents lasting from seventeen to nineteen days. The newly hatched squab (nestling) has pale yellow down and a flesh-coloured bill with a dark band. For the first few days, the baby squab is tended and fed (through regurgitation) exclusively on "crop milk" (also called "pigeon milk" or "pigeon's milk"). The pigeon milk is produced in the crops of both parents in all species of pigeons and doves. The fledging period is about 30 days.

  

Predators

  

With only its flying abilities protecting it from predation, rock pigeons are a favorite almost around the world for a wide range of raptorial birds. In fact, with feral pigeons existing in almost every city in the world, they may form the majority of prey for several raptor species who live in urban areas. Peregrine falcons and Eurasian sparrowhawks are natural predators of pigeons that are quite adept at catching and feeding upon this species. Up to 80% of the diet of peregrine falcons in several cities that have breeding falcons is composed of feral pigeons. Some common predators of feral pigeons in North America are opossums, raccoons, red-tailed hawks, great horned owls, eastern screech owls and Accipiters. The birds that predate pigeons in North America can range in size from American kestrels to golden eagles and can even include gulls, crows, and ravens. On the ground the adults, their young and their eggs are at risk from feral and domestic cats. Doves and pigeons are considered to be game birds as many species have been hunted and used for food in many of the countries in which they are native.

  

Parasites

  

Pigeons may harbour a diverse parasite fauna. They often host the intestinal helminths Capillaria columbae and Ascaridia columbae. Their ectoparasites include the Ischnoceran lice Columbicola columbae, Campanulotes bidentatus compar, the Amblyceran lice Bonomiella columbae, Hohorstiella lata, Colpocephalum turbinatum, the mites Tinaminyssus melloi, Dermanyssus gallinae, Dermoglyphus columbae, Falculifer rostratus, and Diplaegidia columbae. The hippoboscid fly Pseudolynchia canariensis is a typical blood-sucking ectoparasite of pigeons, found only in tropical and sub-tropical regions.

  

Human health

  

Pigeons have been falsely associated with the spread of human diseases. Contact with pigeon droppings poses a minor risk of contracting histoplasmosis, cryptococcosis, and psittacosis, and exposure to both droppings and feathers can produce bird fancier's lung. Pigeons are not a major concern in the spread of West Nile virus; though they can contract it, they do not appear to be able to transmit it. Pigeons are, however, at potential risk for carrying and spreading avian influenza. One study has shown that adult pigeons are not clinically susceptible to the most dangerous strain of avian influenza, the H5N1, and that they did not transmit the virus to chickens. Other studies have presented evidence of clinical signs and neurological lesions resulting from infection, but found that the pigeons did not transmit the disease to chickens reared in direct contact with them. Pigeons were found to be "resistant or minimally susceptible" to other strains of avian influenza, such as the H7N7.

  

Domestication

  

Rock doves have been domesticated for several thousand years, giving rise to the domestic pigeon (Columba livia domestica). As well as food and pets, domesticated pigeons are used as homing pigeons. They were in the past also used as carrier pigeons, and so-called war pigeons have played significant roles during wartime, with many pigeons having received bravery awards and medals for their services in saving hundreds of human lives: including, notably, the British pigeon Cher Ami who received the Croix de Guerre for her heroic actions during World War I, and the Irish Paddy and the American G.I. Joe, who both received the Dickin Medal, amongst 32 pigeons to receive this medallion, for their gallant and brave actions during World War II. There are numerous breeds of fancy pigeons of all sizes, colours and types.

  

Feral pigeon

  

Many domestic birds have escaped or been released over the years, and have given rise to the feral pigeon. These show a variety of plumages, although some have the blue barred pattern as does the pure rock dove. Feral pigeons are found in large numbers in cities and towns all over the world. The scarcity of the pure wild species is partly due to interbreeding with feral birds.

  

Osmoregulation

  

Challenges

  

Water is taken in by the Columba livia directly by drinking water or indirectly from the food they ingest. They drink water through a process called double-suction mechanism. The daily diet of the Pigeon places many physiologically challenges it must over come through osmoregulation. Protein intake for example causes an excess toxins of amine groups when it is broken down for energy. To regulate this excess and secrete these unwanted toxins the Columba livia must remove the amine groups as uric acid. Nitrogen excretion through uric acid can be considered an advantage because it doesn't require a lot of water and isn't very soluble, but producing it takes more energy because of its complex molecular composition.

  

The danger of desiccation is a major threat to animals living on land. Water is lost in urine and feces, but evaporation is the principal route of water loss. Water lost must be replaced by drinking and water in food. Dehydration or salt-loading decreases the filtration rate primarily by the shut down of the nephrons, which is controlled by an antidiuretic hormone, arginine vasotocin. Pigeons adjust their drinking rates and food intake in parallel and when adequate water is unavailable for excretion, food intake is limited to maintain water balance. As Columbia livia inhabit arid environments, research attributes this to their strong flying capabilities to reach the available water sources, not because of exceptional potential for water conservation. Columba livia kidneys, like mammalian kidneys, are capable of producing urine hyperosmotic to the plasma utilizing the processes of filtration, reabsorption and secretion, which will be discussed later and explained through the Starling-Landis Hypothesis. The medullary cones function as countercurrent units that achieve the production of hyperosmotic urine. Hyperosmotic urine can be understood in light of the law of diffusion and osmolarity.

  

Organ of osmoregulation

  

Unlike a number other bird species which have the salt gland as the primary osmoregulatory organ, Columba livia does not use their salt gland even though it exists. Columba livia uses the function of their kidneys to maintain homeostatic balance of ions such as sodium and potassium while preserving water quantity in the body. Filtration of the blood, reabsorption of ions and water, and secretion of uric acid are all components of the kidney's process. The kidneys of Columba livia are located in its pelvic region. Columba livia has two kidneys that are coupled, each having three partially separate lobes; the posterior lobe is the largest in size. Like mammalian kidneys, the avian kidney contains a medullary region and a cortical region. Peripherally located around the cortical region, the collecting ducts gather into cone-like ducts, medullary cones, which converge into the ureters. There are two types of nephrons in the kidney; nephrons that are located in the cortex and do not contain the loop of Henle are called loopless nephrons, the other type are called looped or mammalian nephrons. Looped nephrons contain the loop of Henle that continue down into the medulla then enter the distal tubule drain towards the ureter. Mammals generally have a more vascularized glomeruli than the nephrons in birds. The nephrons of avian species can not produce urine that is hyperosmotic to the blood, but, the loop of Henle utilizes countercurrent multiplication which allows it to become hyperosmotic in the collecting duct. This alternation of permeability between different sections of the ascending and descending loop allows for the elevation of the urine osmotic pressure 2.5 times above the blood osmotic pressure.

  

Specialize cell types involved in osmoregulation

  

The integumentary system functions in osmoregulation by acting as a barrier between the extracellular compartment and the environment to regulate water gain and loss, as well as solute flux. The permeability of the integument to water and solutes varies from animal to animal.The excretory system is responsible for regulating water and solute levels in the body fluids. Pigeons can produce hyperosmotic urine but their renal system is different from other animals. They do not produce concentrated urine to reduce water loss but produce a whitish part called urate. It is considered as uric acid solid crystals and it is less toxic than urea. The wastes move from the blood of the peritubular capillaries passes through the tubule cells and into the collecting ducts and transported as urate (uric acid). Urate is then transported to the cloaca and from there to the large intestine where uric acid particle and water and solutes in the urine can be reabsorbed and balanced. Thus this allows them to save their body water instead of excreting large volume of dilute urea. Cells of the proximal tubule have numerous microvilli and mitochondria which provide surface area and energy to the proximal tubule cells.

  

The blood pH is regulated by the A and B types of cells located in distal tubule and collecting duct. The A type cells are acid secreting cells that have a proton ATPase in the apical membrane and a Cl-/ HCO3- exchange system in the basolateral membrane whereas, the B type cells are base secreting cells, which secrete bicarbonate into the lumen of the tubule in exchange for chloride ions. The regulation of pH in blood determines whether bicarbonate is reabsorbed or secreted.

  

Transport mechanisms of osmoregulation

  

The filtrate contains lots of important substances. In the proximal tubules of the Columbia livia kidney, substances that are needed, such as vitamins and glucose are reabsorbed into the blood. Their kidney has a variety of ion channels involved in salt and water transport. Water is reabsorbed through aquaporins which are present in the lumen of proximal tubule, basolateral membrane, and blood vessel near proximal tubule. Water flows from the epithelial cells into the blood via osmosis. Since osmosis occurs, the osmolarity of the filtrate remains isotonic. Sodium/Potassium/ATPase transporter is located in the basolateral membrane of the epithelial cell, which is opposite of the lumen of proximal tubule, and actively pumps sodium out of the cell into the blood.

  

Special adaptations

  

Eggshell's gas exchange and water loss

  

Gas exchange across eggshells results in water loss from the egg. However, the egg must retain enough water to hydrate the embryo. This results in the knowledge that changing temperatures and humidity can affect the eggshell's architecture. Behavioral adaptations in Columba livia and other birds, such as the incubation of their eggs, can help with the effects of these changing environments. It was found that eggshell architecture undergoes selection decoupled from behavioral effects, and that humidity may be a driving selective pressure. Low humidity requires enough water to keep the embryo from desiccation, and high humidity needs enough water loss to facilitate the initiation of pulmonary respiration. The water loss from the eggshell is directly linked to the growth rate of the species. The ability of the embryo to tolerate extreme water loss is due to the parental behavior in species colonizing in different environments. Studies have been done showing that wild habitats of Columba livia and other birds have a higher rate tolerance of various humidity levels, but Columba livia do prefer areas where the humidity closely matched their native breeding conditions. The pore areas of the shells allow water to diffuse in and out of the shell, preventing the possible harming of the embryo due to the high rates of water retention. If an eggshell is thinner, it can cause a decrease in pore length, and an increase in conductance and pore area. A thinner eggshell can also cause a decrease in mechanical restriction of the embryo.

  

Thermoregulation

  

Temperature changes

  

The Columbia Livia is habituated within many vast environments with varying degrees of temperatures. Like all vertebrates, Columbia Livia perspires heat through evaporation of water when temperatures are high in the environment. It’s preferred niche temperature ranges between +39 - +42 degrees Celsius.

  

Peripheral thermoreceptors of the Columbia Liva regulate its body’s response to the cold. During low temperatures, which put the Columbia Liva’s body under stress it accommodates extreme temperatures by increasing its internal temperatures within the core and spinal cord. Along with this increase, there is also a decrease in temperature within the legs, neck and back skin.

  

Physiological challenges placed on organism

  

Columba Livia stabilize their internal body temperature independent of alteration in ambient temperature. They are also able to withstand extreme climate conditions, such as ambient temperature range of +42 to -40 °C. The temperature regulation of Columba Livia is generally based on the principle of endotherms. Being endothermic they use metabolic heat to raise body temperature. Columba Livia are also homeotherms, meaning that they are thermoregulators and maintain a relatively constant body temperature. The heat exchange between animals and their surroundings occurs due to conduction, convection, radiation and evaporation. Fourier's Law of Heat Conduction describes the loss of heat experienced by animals through conduction. At low ambient temperatures the endothermic animals are able to reduce their heat loss by lowering the skin temperature and by increasing their peripheral insulation, which is discussed later.

  

Behavioral adaptations

  

Columba Livia does a few things to regulate its body temperature. Normally it will drink water after they have eaten, but when stressed by heat they can drink whenever needed to lower its body temperature. Another way it can regulate its heat is through Ptilomotor responses. Ptilomotor responses allow for better insulation of the body, because smooth muscle contractions make the feathers stand up straighter, which traps more air next to the skin. Columba Livia exhibits Ta (ambient temperature) selecting behavior. It will seek out its desired thermal neutral zone temperatures, in order to expend less energy heating and cooling its body.

  

Physiological changes to blood flow

  

Areas poorly or not insulated by feathers such as the beak, head, and feet have vasomotor responses. To reduce heat loss while in cold atmospheric temperatures, endothermic animals will lower the skin temperature by restricting the amount of blood that reaches it, called vasoconstriction. The sympathetic nervous system stimulates the constriction of the vascular beds at low temperatures. Vasodilation does the opposite; to increase the heat lost by convection after high muscular activity or from heat stress, Columba Livia increases its blood flow to the surface of its body. Cutaneous tissue of the beak, feet, and bends in the wings are dilated. To regulate brain temperature it uses the vascular vessels(plexus) in the eyes, in combination with vasomotion. Evaporation is usually controlled by sweat glands, however, birds use their breathing pattern to control heat dissipation. The frequency in breathing depends on body temperature, Tb; to increase respiratory evaporation the bird's breathing rate would increase. The most important thermoregulatory mechanism is called shivering thermogenesis. The skeletal muscles are used to generate heat through contractions when the surrounding air, Ta, is below its thermal neutral zone. As the temperature drops, the shivering increases to generate more heat. Non-shivering thermogenesis is used by Columba Livia, when exposed to cold to generate heat; an increase in Na+/K+-ATPase activity drives this mechanism in the liver.

  

Special adaptations

  

A study was done by Michael E. Rashotte, et al. (1998) comparing the vigilance states and body temperature is different within in fed and fasted pigeons (Columba Livia). Fasting induces nocturnal hypothermia in pigeons. There are different sleep patterns associated with heat production in pigeons, slow wave sleep (SWS) and paradoxical sleep (PS). An increase of SWS and PS was compared to the fasting-induced nocturnal hypothermia by comparing body temperature (Tb) and vigilance states when pigeons were fed and fasted. It was found that the Tb was decreasing near the beginning of the dark phase and that the time spent in SWS and PS was elevated in the fasting pigeons due to the increase of frequency and duration. When body temperature was low in the middle of the dark phase, it showed that SWS was elevated but it did not affect the PS stage. When the body temperature was high during the last hours of dark, SWS remained elevated in fasting-induced and that PS was relatively high. Rashotte, et al. (1998) suggests that more evidence is needed to confirm these results but he suggests that pigeons may be best viewed as an animal that has a shallow hypometabolic state that fall within (or very close to) their euthermic range. It is also seen that a pigeon’s vigilance stage can be compared similarly to mammals in hibernation.

  

Specialized organs or anatomy involved in thermoregulation

  

The purpose of thermoregulation is to maintain body temperature by producing heat through physiological and metabolic reactions. Heat gain should equal to rates of heat loss. If the body temperature is unbalanced, the animal becomes either warmer or colder. Heat production in birds is associated to shivering. The large flight muscles- pectoralis as well as the leg muscles generate heat by shivering.

  

Columba Livia have strong wings with flexible feathers which provide enough insulation to keep their body warm and dry. The fat layers and feathers reduce the flow of heat between an animal and its environment and lower the energy cost of keeping warm. In some birds the heat loss from the legs and feet is limited in cold weather because of a countercurrent mechanism that saves heat and in hot weather it can serve as heat radiators which increase blood flow.

  

Thermoregulation in birds requires cooling as well as warming. At low temperature birds can tuck head and neck under their wings to reduce heat loss. The heat is lost by the pigeons as an insensible heat by evaporation of water from the respiratory system and skin when temperature gradient is less and relative humidity is low. At the relatively high temperature birds increase their respiration rate to increase their cooling by evaporation. The panting is important in birds which involves gular flutter. The pouch richly supplied with blood vessels in the floor of the mouth; the rapid movement of the upper throat tissues - fluttering the pouch increases evaporation. Pigeons can use evaporative cooling to keep body temperature close to 40 °C in air temperatures as high as 60 °C, as long as they have sufficient water.

  

Also from previous studies experiment shows that a bird is capable of evaporating enough water from the cloaca for thermoregulation and results suggests that some birds’ cloacal evaporation can be controlled and could serve as an important maneuver for thermoregulation at high ambient temperatures.

  

Regulation of metabolism

  

Columba livia as homeothermic animals, are able to regulate heat production and external heat loss in autonomic ways, by a feedback control system. Negative feedback is the most important principle for regulation; a decrease of ambient temperature evoked by cold activates some thermoregulatory effector mechanisms, which reduce the heat loss and increase the internal heat production. The metabolic rate of resting Columba Livia at neutral ambient temperature, is reduced by a level of 5-10% during drowsiness, sleep and darkness. An increase follows every kind of muscle activity, such as flying, which increases metabolic rate by 10-12 times. Heat production throughout the day contributes to a high level of body temperature.

  

[Credit: en.wikipedia.org/]

  

Au niveau de la vessie gazeuse de ce poisson osseux, on découvre cet assemblage de capillaires artériels et veineux disposés à contre-courant, c’est-à-dire parallèles mais

circulant en sens opposés. Ainsi agencés, ils constituent un réseau admirable (rete mirabile : voir P8) qui représente une vaste surface d’échanges de gaz. Les globules rouges se repèrent à leur noyau bien central (flèches) et à leur teinte orangée, mais il est illusoire de différencier capillaires artériels afférents et veineux efférents.

 

- Pour plus de détails ou précisions, voir « Atlas of Fish Histology » CRC Press, ou « Histologie illustrée du poisson » (QUAE) ou s'adresser à Franck Genten (fgenten@gmail.com)

----------------------------------------------------------------------------------

In many teleost species the circulatory system of the

swim bladder is characterized by the presence of a

countercurrent arrangement of arterial and venous

capillaries, termed the rete mirabile (see P8) which supplies the bladder with gases. The red blood cells are easily recognizable by their central nuclei (arrows) but it is impossible to distinguish afferent arterial capillaries from efferent venous ones.

 

- For more information or details, see « Atlas of Fish Histology » CRC Press, or « Histologie illustrée du poisson » (QUAE) or contact Franck Genten (fgenten@gmail.com)

 

Large On Black

 

One small feet for a duckling, One Giant leap for Duckburg! - McDuck, Scrooge

 

Ok, that quote was made up. It nowhere appears in Duck Tales (by far my most favourite cartoon) and the ducks roaming around in Boulder remind me of it.

 

This one was shot at Denver Zoo on a cold cold day.

 

Q: Why dont they get frostbites?

 

A: (sourced from web) To maintain healthy tissue, and prevent frostbite, you need to provide nutrients to the tissue and keep it warm enough so that it doesn’t freeze. In ducks (and other cold-weather birds), this is done by a physiological set up called “countercurrent”. Think of venous blood, cold from exposure to the air, flowing back into the body from the feet. Too much cold blood will bring the core body temperature down, leading to hypothermia. Then think of warm, arterial blood rushing from the heart. In animals adapted to the cold, the veins and arteries run very close together. As cold blood runs up the leg from the foot and passes by the artery, it picks up most of the heat from the artery. Thus, by the time arterial blood reaches the foot, it is very cool, so does not lose too much heat in transfer with cold water. Blood flow is carefully regulated to maintain the delicate balance of providing blood but maintaining core body temperature.

 

All hail Scrooge!!

The "Swan Lake" painting narrates the story of the famous ballet. Swan Lake (1.3 x 2.9 metres) is painted on doubly primed canvas in acrylic. The geometrical scaffolding is double Golden Rectangle between upper and lower strips as in Pablo PIcasso's "Guernica", and superimposed upon a Mediaeval Muslim Tile Art pattern (as in the Alhambra, Spain)

 

The painting tells the story of the Tchaikovsky-orchestrated ballet "Swan Lake" in 4 Acts -in which (1) the Prince dances at Court, (2) he dances with Odette and the Swans in the Forest, (3) he is seduced by Odile at the Court and (4) The Prince and Odette plunging into the Lake, the Sorcerer dies and Odette expires on a dry lake bed (a metaphor for looming global warming catastrophe).

 

For a detailed discussion of the Swan Lake painting and its global warming metaphor see Gideon Polya, “Swan Lake. ”Swan Lake” Painting. Fear, Greed, Lying & Values, Biosphere & Market Collapse”: sites.google.com/site/artforpeaceplanetmotherchild/swan-lake . For details of related huge paintings by Gideon Polya see "Art for Peace, Planet, Mother & Child": sites.google.com/site/artforpeaceplanetmotherchild/home .

 

Climate Genocide.

 

The Climate Genocide website documents authoritative opinions of leading climate scientists, climate economists, climate analysts and world figures who predict a massive death toll from unaddressed, man-made global warming.

 

Both Dr James Lovelock FRS (Gaia hypothesis) and Professor Kevin Anderson ( Director, Tyndall Centre for Climate Change Research, University of Manchester, UK) have recently estimated that fewer than 1 billion people will survive this century due to unaddressed, man-made global warming – noting that the world population is expected to reach 9.5 billion by 2050, these estimates translate to a climate genocide involving deaths of 10 billion people this century, this including 6 billion under-5 year old infants, 3 billion Muslims in a terminal Muslim Holocaust, 2 billion Indians, 1.3 billion non-Arab Africans, 0.5 billion Bengalis, 0.3 billion Pakistanis and 0.3 billion Bangladeshis (see "Climate Genocide": sites.google.com/site/climategenocide/ ).

 

Of course, it just doesn't have to happen - thus see Professor James Hansen (NASA, GISS, Columbia University), “It’s possible to avert the climate crisis”, Countercurrents, 29 November 2009: www.countercurrents.org/hansen291109.htm .

  

A camel (from Latin: camelus and Greek: κάμηλος (kamēlos) from Ancient Semitic: gāmāl) is an even-toed ungulate in the genus Camelus that bears distinctive fatty deposits known as "humps" on its back. Camels have long been domesticated and, as livestock, they provide food (milk and meat) and textiles (fiber and felt from hair). Camels are working animals especially suited to their desert habitat and are a vital means of transport for passengers and cargo. There are three surviving species of camel. The one-humped dromedary makes up 94% of the world's camel population, and the two-humped Bactrian camel makes up 6%. The wild Bactrian camel is a separate species and is now critically endangered.

 

The word camel is also used informally in a wider sense, where the more correct term is "camelid", to include all seven species of the family Camelidae: the true camels (the above three species), along with the "New World" camelids: the llama, the alpaca, the guanaco, and the vicuña, which belong to the separate tribe Lamini. Camelids originated in North America during the Eocene, with the ancestor of modern camels, Paracamelus, migrating across the Bering land bridge into Asia during the late Miocene, around 6 million years ago.

 

Taxonomy

Extant species

Three species are extant:

 

ImageCommon nameScientific nameDistribution

Bactrian camelCamelus bactrianusDomesticated; Central Asia, including the historical region of Bactria.

Dromedary / Arabian camelCamelus dromedariusDomesticated; the Middle East, Sahara Desert, and South Asia; introduced to Australia

Wild Bactrian camelCamelus ferusRemote areas of northwest China and Mongolia

Biology

The average life expectancy of a camel is 40 to 50 years. A full-grown adult dromedary camel stands 1.85 m (6 ft 1 in) at the shoulder and 2.15 m (7 ft 1 in) at the hump. Bactrian camels can be a foot taller. Camels can run at up to 65 km/h (40 mph) in short bursts and sustain speeds of up to 40 km/h (25 mph). Bactrian camels weigh 300 to 1,000 kg (660 to 2,200 lb) and dromedaries 300 to 600 kg (660 to 1,320 lb). The widening toes on a camel's hoof provide supplemental grip for varying soil sediments.

 

The male dromedary camel has an organ called a dulla in his throat, a large, inflatable sac that he extrudes from his mouth when in rut to assert dominance and attract females. It resembles a long, swollen, pink tongue hanging out of the side of the camel's mouth. Camels mate by having both male and female sitting on the ground, with the male mounting from behind. The male usually ejaculates three or four times within a single mating session. Camelids are the only ungulates to mate in a sitting position.

 

Ecological and behavioral adaptations

  

Camel humps store fat, which are used as nourishment when food is scarce. If a camel uses the fat inside the hump, the hump will become limp and droop down

Camels do not directly store water in their humps; they are reservoirs of fatty tissue. When this tissue is metabolized, it yields a greater mass of water than that of the fat processed. This fat metabolization, while releasing energy, causes water to evaporate from the lungs during respiration (as oxygen is required for the metabolic process): overall, there is a net decrease in water.

 

Camels have a series of physiological adaptations that allow them to withstand long periods of time without any external source of water. The dromedary camel can drink as seldom as once every 10 days even under very hot conditions, and can lose up to 30% of its body mass due to dehydration. Unlike other mammals, camels' red blood cells are oval rather than circular in shape. This facilitates the flow of red blood cells during dehydration and makes them better at withstanding high osmotic variation without rupturing when drinking large amounts of water: a 600 kg (1,300 lb) camel can drink 200 L (53 US gal) of water in three minutes.

 

Camels are able to withstand changes in body temperature and water consumption that would kill most other mammals. Their temperature ranges from 34 °C (93 °F) at dawn and steadily increases to 40 °C (104 °F) by sunset, before they cool off at night again. In general, to compare between camels and the other livestock, camels lose only 1.3 liters of fluid intake every day while the other livestock lose 20 to 40 liters per day. Maintaining the brain temperature within certain limits is critical for animals; to assist this, camels have a rete mirabile, a complex of arteries and veins lying very close to each other which utilizes countercurrent blood flow to cool blood flowing to the brain. Camels rarely sweat, even when ambient temperatures reach 49 °C (120 °F). Any sweat that does occur evaporates at the skin level rather than at the surface of their coat; the heat of vaporization therefore comes from body heat rather than ambient heat. Camels can withstand losing 25% of their body weight in water, whereas most other mammals can withstand only about 12–14% dehydration before cardiac failure results from circulatory disturbance.

 

When the camel exhales, water vapor becomes trapped in their nostrils and is reabsorbed into the body as a means to conserve water. Camels eating green herbage can ingest sufficient moisture in milder conditions to maintain their bodies' hydrated state without the need for drinking.

  

Domesticated camel calves lying in sternal recumbency, a position that aids heat loss

The camel's thick coat insulates it from the intense heat radiated from desert sand; a shorn camel must sweat 50% more to avoid overheating. During the summer the coat becomes lighter in color, reflecting light as well as helping avoid sunburn. The camel's long legs help by keeping its body farther from the ground, which can heat up to 70 °C (158 °F). Dromedaries have a pad of thick tissue over the sternum called the pedestal. When the animal lies down in a sternal recumbent position, the pedestal raises the body from the hot surface and allows cooling air to pass under the body.

 

Camels' mouths have a thick leathery lining, allowing them to chew thorny desert plants. Long eyelashes and ear hairs, together with nostrils that can close, form a barrier against sand. If sand gets lodged in their eyes, they can dislodge it using their translucent third eyelid (also known as the nictitating membrane). The camels' gait and widened feet help them move without sinking into the sand.

 

The kidneys and intestines of a camel are very efficient at reabsorbing water. Camels' kidneys have a 1:4 cortex to medulla ratio. Thus, the medullary part of a camel's kidney occupies twice as much area as a cow's kidney. Secondly, renal corpuscles have a smaller diameter, which reduces surface area for filtration. These two major anatomical characteristics enable camels to conserve water and limit the volume of urine in extreme desert conditions. Camel urine comes out as a thick syrup, and camel faeces are so dry that they do not require drying when used to fuel fires.

 

The camel immune system differs from those of other mammals. Normally, the Y-shaped antibody molecules consist of two heavy (or long) chains along the length of the Y, and two light (or short) chains at each tip of the Y. Camels, in addition to these, also have antibodies made of only two heavy chains, a trait that makes them smaller and more durable. These "heavy-chain-only" antibodies, discovered in 1993, are thought to have developed 50 million years ago, after camelids split from ruminants and pigs. Camels suffer from surra caused by Trypanosoma evansi wherever camels are domesticated in the world: 2  and resultantly camels have evolved trypanolytic antibodies as with many mammals. In the future, nanobody/single-domain antibody therapy will surpass natural camel antibodies by reaching locations currently unreachable due to natural antibodies' larger size.: 788  Such therapies may also be suitable for other mammals.: 788  Tran et al. 2009 provides a new reference test for surra (T. evansi) of camel. They use recombinant Invariant Surface Glycoprotein 75 (rISG75, an Invariant Surface Glycoprotein) and ELISA. The Tran test has high test specificity and appears likely to work just as well for T. evansi in other hosts, and for a pan-Trypanozoon test, which would also be useful for T. b. brucei, T. b. gambiense, T. b. rhodesiense, and T. equiperdum.

 

Genetics

The karyotypes of different camelid species have been studied earlier by many groups, but no agreement on chromosome nomenclature of camelids has been reached. A 2007 study flow sorted camel chromosomes, building on the fact that camels have 37 pairs of chromosomes (2n=74), and found that the karyotype consisted of one metacentric, three submetacentric, and 32 acrocentric autosomes. The Y is a small metacentric chromosome, while the X is a large metacentric chromosome.

 

The hybrid camel, a hybrid between Bactrian and dromedary camels, has one hump, though it has an indentation 4–12 cm (1.6–4.7 in) deep that divides the front from the back. The hybrid is 2.15 m (7 ft 1 in) at the shoulder and 2.32 m (7 ft 7 in) tall at the hump. It weighs an average of 650 kg (1,430 lb) and can carry around 400 to 450 kg (880 to 990 lb), which is more than either the dromedary or Bactrian can.

 

According to molecular data, the wild Bactrian camel (C. ferus) separated from the domestic Bactrian camel (C. bactrianus) about 1 million years ago. New World and Old World camelids diverged about 11 million years ago. In spite of this, these species can hybridize and produce viable offspring. The cama is a camel-llama hybrid bred by scientists to see how closely related the parent species are. Scientists collected semen from a camel via an artificial vagina and inseminated a llama after stimulating ovulation with gonadotrophin injections. The cama is halfway in size between a camel and a llama and lacks a hump. It has ears intermediate between those of camels and llamas, longer legs than the llama, and partially cloven hooves. Like the mule, camas are sterile, despite both parents having the same number of chromosomes.

 

Evolution

The earliest known camel, called Protylopus, lived in North America 40 to 50 million years ago (during the Eocene). It was about the size of a rabbit and lived in the open woodlands of what is now South Dakota. By 35 million years ago, the Poebrotherium was the size of a goat and had many more traits similar to camels and llamas. The hoofed Stenomylus, which walked on the tips of its toes, also existed around this time, and the long-necked Aepycamelus evolved in the Miocene. The split between the tribes Camelini, which contains modern camels and Lamini, modern llamas, alpacas, vicuñas, and guanacos, is estimated to have occurred over 16 million years ago.

 

The ancestor of modern camels, Paracamelus, migrated into Eurasia from North America via Beringia during the late Miocene, between 7.5 and 6.5 million years ago. During the Pleistocene, around 3 to 1 million years ago, the North American Camelidae spread to South America as part of the Great American Interchange via the newly formed Isthmus of Panama, where they gave rise to guanacos and related animals. Populations of Paracamelus continued to exist in the North American Arctic into the Early Pleistocene. This creature is estimated to have stood around nine feet (2.7 metres) tall. The Bactrian camel diverged from the dromedary about 1 million years ago, according to the fossil record.

 

The last camel native to North America was Camelops hesternus, which vanished along with horses, short-faced bears, mammoths and mastodons, ground sloths, sabertooth cats, and many other megafauna as part of the Quaternary extinction event, coinciding with the migration of humans from Asia at the end of the Pleistocene, around 13–11,000 years ago.

 

Domestication

Like horses, camels originated in North America and eventually spread across Beringia to Asia. They survived in the Old World, and eventually humans domesticated them and spread them globally. Along with many other megafauna in North America, the original wild camels were wiped out during the spread of the first indigenous peoples of the Americas from Asia into North America, 10 to 12,000 years ago; although fossils have never been associated with definitive evidence of hunting.

 

Most camels surviving today are domesticated. Although feral populations exist in Australia, India and Kazakhstan, wild camels survive only in the wild Bactrian camel population of the Gobi Desert.

 

History

When humans first domesticated camels is disputed. Dromedaries may have first been domesticated by humans in Somalia or South Arabia sometime during the 3rd millennium BC, the Bactrian in central Asia around 2,500 BC, as at Shar-i Sokhta (also known as the Burnt City), Iran. A study from 2016, which genotyped and used world-wide sequencing of modern and ancient mitochondrial DNA (mtDNA), suggested that they were initially domesticated in the southeast Arabian Peninsula, with the Bactrian type later being domesticated around Central Asia.

 

Martin Heide's 2010 work on the domestication of the camel tentatively concludes that humans had domesticated the Bactrian camel by at least the middle of the third millennium somewhere east of the Zagros Mountains, with the practice then moving into Mesopotamia. Heide suggests that mentions of camels "in the patriarchal narratives may refer, at least in some places, to the Bactrian camel", while noting that the camel is not mentioned in relationship to Canaan. Heide and Joris Peters reasserted that conclusion in their 2021 study on the subject.

 

In 2009-2013, excavations in the Timna Valley by Lidar Sapir-Hen and Erez Ben-Yosef discovered what may be the earliest domestic camel bones yet found in Israel or even outside the Arabian Peninsula, dating to around 930 BC. This garnered considerable media coverage, as it is strong evidence that the stories of Abraham, Jacob, Esau, and Joseph were written after this time.

 

The existence of camels in Mesopotamia—but not in the eastern Mediterranean lands—is not a new idea. The historian Richard Bulliet did not think that the occasional mention of camels in the Bible meant that the domestic camels were common in the Holy Land at that time. The archaeologist William F. Albright, writing even earlier, saw camels in the Bible as an anachronism.

 

The official report by Sapir-Hen and Ben-Joseph notes:

 

The introduction of the dromedary camel (Camelus dromedarius) as a pack animal to the southern Levant ... substantially facilitated trade across the vast deserts of Arabia, promoting both economic and social change (e.g., Kohler 1984; Borowski 1998: 112–116; Jasmin 2005). This ... has generated extensive discussion regarding the date of the earliest domestic camel in the southern Levant (and beyond) (e.g., Albright 1949: 207; Epstein 1971: 558–584; Bulliet 1975; Zarins 1989; Köhler-Rollefson 1993; Uerpmann and Uerpmann 2002; Jasmin 2005; 2006; Heide 2010; Rosen and Saidel 2010; Grigson 2012). Most scholars today agree that the dromedary was exploited as a pack animal sometime in the early Iron Age (not before the 12th century [BC])

 

and concludes:

 

Current data from copper smelting sites of the Aravah Valley enable us to pinpoint the introduction of domestic camels to the southern Levant more precisely based on stratigraphic contexts associated with an extensive suite of radiocarbon dates. The data indicate that this event occurred not earlier than the last third of the 10th century [BC] and most probably during this time. The coincidence of this event with a major reorganization of the copper industry of the region—attributed to the results of the campaign of Pharaoh Shoshenq I—raises the possibility that the two were connected, and that camels were introduced as part of the efforts to improve efficiency by facilitating trade.

 

Textiles

Main article: Camel hair

Desert tribes and Mongolian nomads use camel hair for tents, yurts, clothing, bedding and accessories. Camels have outer guard hairs and soft inner down, and the fibers are sorted by color and age of the animal. The guard hairs can be felted for use as waterproof coats for the herdsmen, while the softer hair is used for premium goods. The fiber can be spun for use in weaving or made into yarns for hand knitting or crochet. Pure camel hair is recorded as being used for western garments from the 17th century onwards, and from the 19th century a mixture of wool and camel hair was used.

 

Military uses

Main article: Camel cavalry

By at least 1200 BC the first camel saddles had appeared, and Bactrian camels could be ridden. The first saddle was positioned to the back of the camel, and control of the Bactrian camel was exercised by means of a stick. However, between 500 and 100 BC, Bactrian camels came into military use. New saddles, which were inflexible and bent, were put over the humps and divided the rider's weight over the animal. In the seventh century BC the military Arabian saddle evolved, which again improved the saddle design slightly.

 

Military forces have used camel cavalries in wars throughout Africa, the Middle East, and into the modern-day Border Security Force (BSF) of India (though as of July 2012, the BSF planned the replacement of camels with ATVs). The first documented use of camel cavalries occurred in the Battle of Qarqar in 853 BC. Armies have also used camels as freight animals instead of horses and mules.

 

The East Roman Empire used auxiliary forces known as dromedarii, whom the Romans recruited in desert provinces. The camels were used mostly in combat because of their ability to scare off horses at close range (horses are afraid of the camels' scent), a quality famously employed by the Achaemenid Persians when fighting Lydia in the Battle of Thymbra (547 BC).

 

19th and 20th centuries

A photo of Bulgarian military-transport camels in 1912

A camel caravan of the Bulgarian military during the First Balkan War, 1912

The United States Army established the U.S. Camel Corps, stationed in California, in the 19th century.[19] One may still see stables at the Benicia Arsenal in Benicia, California, where they nowadays serve as the Benicia Historical Museum. Though the experimental use of camels was seen as a success (John B. Floyd, Secretary of War in 1858, recommended that funds be allocated towards obtaining a thousand more camels), the outbreak of the American Civil War in 1861 saw the end of the Camel Corps: Texas became part of the Confederacy, and most of the camels were left to wander away into the desert.

 

France created a méhariste camel corps in 1912 as part of the Armée d'Afrique in the Sahara in order to exercise greater control over the camel-riding Tuareg and Arab insurgents, as previous efforts to defeat them on foot had failed. The Free French Camel Corps fought during World War II, and camel-mounted units remained in service until the end of French rule over Algeria in 1962.

 

In 1916, the British created the Imperial Camel Corps. It was originally used to fight the Senussi, but was later used in the Sinai and Palestine Campaign in World War I. The Imperial Camel Corps comprised infantrymen mounted on camels for movement across desert, though they dismounted at battle sites and fought on foot. After July 1918, the Corps began to become run down, receiving no new reinforcements, and was formally disbanded in 1919.

 

In World War I, the British Army also created the Egyptian Camel Transport Corps, which consisted of a group of Egyptian camel drivers and their camels. The Corps supported British war operations in Sinai, Palestine, and Syria by transporting supplies to the troops.

 

The Somaliland Camel Corps was created by colonial authorities in British Somaliland in 1912; it was disbanded in 1944.

 

Bactrian camels were used by Romanian forces during World War II in the Caucasian region. At the same period the Soviet units operating around Astrakhan in 1942 adopted local camels as draft animals due to shortage of trucks and horses, and kept them even after moving out of the area. Despite severe losses, some of these camels ended up as far west as to Berlin itself.

 

The Bikaner Camel Corps of British India fought alongside the British Indian Army in World Wars I and II.

 

The Tropas Nómadas (Nomad Troops) were an auxiliary regiment of Sahrawi tribesmen serving in the colonial army in Spanish Sahara (today Western Sahara). Operational from the 1930s until the end of the Spanish presence in the territory in 1975, the Tropas Nómadas were equipped with small arms and led by Spanish officers. The unit guarded outposts and sometimes conducted patrols on camelback.

 

21st century competition

At the King Abdulaziz Camel Festival, in Saudi Arabia, thousands of camels are paraded and are judged on their lips and humps. The festival also features camel racing and camel milk tasting and has combined prize money of $57m (£40m). In 2018, 12 camels were disqualified from the beauty contest after it was discovered their owners had tried to improve their camel's good looks with injections of botox, into the animals' lips, noses and jaws. In 2021 over 40 camels were disqualified for acts of tampering and deception in beautifying camels.

 

Food uses

Dairy

Main article: Camel milk

Camel milk is a staple food of desert nomad tribes and is sometimes considered a meal itself; a nomad can live on only camel milk for almost a month.

 

Camel milk can readily be made into yogurt, but can only be made into butter if it is soured first, churned, and a clarifying agent is then added. Until recently, camel milk could not be made into camel cheese because rennet was unable to coagulate the milk proteins to allow the collection of curds. Developing less wasteful uses of the milk, the FAO commissioned Professor J.P. Ramet of the École Nationale Supérieure d'Agronomie et des Industries Alimentaires, who was able to produce curdling by the addition of calcium phosphate and vegetable rennet in the 1990s. The cheese produced from this process has low levels of cholesterol and is easy to digest, even for the lactose intolerant.

 

Camels provide food in the form of meat and milk. Approximately 3.3 million camels and camelids are slaughtered each year for meat worldwide. A camel carcass can provide a substantial amount of meat. The male dromedary carcass can weigh 300–400 kg (661–882 lb), while the carcass of a male Bactrian can weigh up to 650 kg (1,433 lb). The carcass of a female dromedary weighs less than the male, ranging between 250 and 350 kg (550 and 770 lb). The brisket, ribs and loin are among the preferred parts, and the hump is considered a delicacy. The hump contains "white and sickly fat", which can be used to make the khli (preserved meat) of mutton, beef, or camel. On the other hand, camel milk and meat are rich in protein, vitamins, glycogen, and other nutrients making them essential in the diet of many people. From chemical composition to meat quality, the dromedary camel is the preferred breed for meat production. It does well even in arid areas due to its unusual physiological behaviors and characteristics, which include tolerance to extreme temperatures, radiation from the sun, water paucity, rugged landscape and low vegetation. Camel meat is reported to taste like coarse beef, but older camels can prove to be very tough, although camel meat becomes tenderer the more it is cooked.

 

Camel is one of the animals that can be ritually slaughtered and divided into three portions (one for the home, one for extended family/social networks, and one for those who cannot afford to slaughter an animal themselves) for the qurban of Eid al-Adha.

 

The Abu Dhabi Officers' Club serves a camel burger mixed with beef or lamb fat in order to improve the texture and taste. In Karachi, Pakistan, some restaurants prepare nihari from camel meat. Specialist camel butchers provide expert cuts, with the hump considered the most popular.

 

Camel meat has been eaten for centuries. It has been recorded by ancient Greek writers as an available dish at banquets in ancient Persia, usually roasted whole. The Roman emperor Heliogabalus enjoyed camel's heel. Camel meat is mainly eaten in certain regions, including Eritrea, Somalia, Djibouti, Saudi Arabia, Egypt, Syria, Libya, Sudan, Ethiopia, Kazakhstan, and other arid regions where alternative forms of protein may be limited or where camel meat has had a long cultural history. Camel blood is also consumable, as is the case among pastoralists in northern Kenya, where camel blood is drunk with milk and acts as a key source of iron, vitamin D, salts and minerals.

 

A 2005 report issued jointly by the Saudi Ministry of Health and the United States Centers for Disease Control and Prevention details four cases of human bubonic plague resulting from the ingestion of raw camel liver.

 

Australia

Camel meat is also occasionally found in Australian cuisine: for example, a camel lasagna is available in Alice Springs. Australia has exported camel meat, primarily to the Middle East but also to Europe and the US, for many years. The meat is very popular among East African Australians, such as Somalis, and other Australians have also been buying it. The feral nature of the animals means they produce a different type of meat to farmed camels in other parts of the world, and it is sought after because it is disease-free, and a unique genetic group. Demand is outstripping supply, and governments are being urged not to cull the camels, but redirect the cost of the cull into developing the market. Australia has seven camel dairies, which produce milk, cheese and skincare products in addition to meat.

 

Religion

Islam

Main article: Animals in Islam

Muslims consider camel meat halal (Arabic: حلال, 'allowed'). However, according to some Islamic schools of thought, a state of impurity is brought on by the consumption of it. Consequently, these schools hold that Muslims must perform wudhu (ablution) before the next time they pray after eating camel meat. Also, some Islamic schools of thought consider it haram (Arabic: حرام, 'forbidden') for a Muslim to perform Salat in places where camels lie, as it is said to be a dwelling place of the Shaytan (Arabic: شيطان, 'Devil'). According to Abu Yusuf (d.798), the urine of camel may be used for medical treatment if necessary, but according to Abū Ḥanīfah, the drinking of camel urine is discouraged.

 

The Islamic texts contain several stories featuring camels. In the story of the people of Thamud, the prophet Salih miraculously brings forth a naqat (Arabic: ناقة, 'milch-camel') out of a rock. After the prophet Muhammad migrated from Mecca to Medina, he allowed his she-camel to roam there; the location where the camel stopped to rest determined the location where he would build his house in Medina.

 

Judaism

See also: Food and drink prohibitions

According to Jewish tradition, camel meat and milk are not kosher. Camels possess only one of the two kosher criteria; although they chew their cud, they do not possess cloven hooves: "But these you shall not eat among those that bring up the cud and those that have a cloven hoof: the camel, because it brings up its cud, but does not have a [completely] cloven hoof; it is unclean for you."

 

Cultural depictions

What may be the oldest carvings of camels were discovered in 2018 in Saudi Arabia. They were analysed by researchers from several scientific disciplines and, in 2021, were estimated to be 7,000 to 8,000 years old. The dating of rock art is made difficult by the lack of organic material in the carvings that may be tested, so the researchers attempting to date them tested animal bones found associated with the carvings, assessed erosion patterns, and analysed tool marks in order to determine a correct date for the creation of the sculptures. This Neolithic dating would make the carvings significantly older than Stonehenge (5,000 years old) and the Egyptian pyramids at Giza (4,500 years old) and it predates estimates for the domestication of camels.

 

Distribution and numbers

A view into a canyon: many camels gathering around a watering hole

Camels in the Guelta d'Archei, in northeastern Chad

There are approximately 14 million camels alive as of 2010, with 90% being dromedaries. Dromedaries alive today are domesticated animals (mostly living in the Horn of Africa, the Sahel, Maghreb, Middle East and South Asia). The Horn region alone has the largest concentration of camels in the world, where the dromedaries constitute an important part of local nomadic life. They provide nomadic people in Somalia and Ethiopia with milk, food, and transportation.

 

Over one million dromedary camels are estimated to be feral in Australia, descended from those introduced as a method of transport in the 19th and early 20th centuries. This population is growing about 8% per year; it was estimated at around 700,000 in 2008. Representatives of the Australian government have culled more than 100,000 of the animals in part because the camels use too much of the limited resources needed by sheep farmers.

 

A small population of introduced camels, dromedaries and Bactrians, wandered through Southwestern United States after having been imported in the 19th century as part of the U.S. Camel Corps experiment. When the project ended, they were used as draft animals in mines and escaped or were released. Twenty-five U.S. camels were bought and exported to Canada during the Cariboo Gold Rush.

 

The Bactrian camel is, as of 2010, reduced to an estimated 1.4 million animals, most of which are domesticated. The Wild Bactrian camel is a separate species and is the only truly wild (as opposed to feral) camel in the world. The wild camels are critically endangered and number approximately 1400, inhabiting the Gobi and Taklamakan Deserts in China and Mongolia.

The reindeer or caribou (Rangifer tarandus) is a species of deer with circumpolar distribution, native to Arctic, subarctic, tundra, boreal, and mountainous regions of Northern Europe, Siberia, and North America. It is the only representative of the genus Rangifer. More recent studies suggest the splitting of reindeer and caribou into six distinct species over their range.

 

Reindeer occur in both migratory and sedentary populations, and their herd sizes vary greatly in different regions. The tundra subspecies are adapted for extreme cold, and some are adapted for long-distance migration.

 

Reindeer vary greatly in size and color from the smallest, the Svalbard reindeer (R. (t.) platyrhynchus), to the largest, Osborn's caribou (R. t. osborni). Although reindeer are quite numerous, some species and subspecies are in decline and considered vulnerable. They are unique among deer (Cervidae) in that females may have antlers, although the prevalence of antlered females varies by species and subspecies.

 

Reindeer are the only successfully semi-domesticated deer on a large scale in the world. Both wild and domestic reindeer have been an important source of food, clothing, and shelter for Arctic people from prehistorical times. They are still herded and hunted today. In some traditional Christmas legends, Santa Claus's reindeer pull a sleigh through the night sky to help Santa Claus deliver gifts to good children on Christmas Eve.

 

Description

Names follow international convention before the recent revision[9] (see Taxonomy below). Reindeer/caribou (Rangifer) vary in size from the smallest, the Svalbard reindeer (R. (t.) platyrhynchus), to the largest, Osborn's caribou (R. t. osborni). They also vary in coat color and antler architecture.

 

The North American range of caribou extends from Alaska through the Yukon, the Northwest Territories and Nunavut throughout the tundra, taiga and boreal forest and south through the Canadian Rocky Mountains. Of the eight subspecies classified by Harding (2022) into the Arctic caribou (R. arcticus), the migratory mainland barren-ground caribou of Arctic Alaska and Canada (R. t. arcticus), summer in tundra and winter in taiga, a transitional forest zone between boreal forest and tundra; the nomadic Peary caribou (R. t. pearyi) lives in the polar desert of the High Arctic Archipelago and Grant's caribou (R. t. granti) lives in the western end of the Alaska Peninsula and the adjacent islands; the other four subspecies, Osborn's caribou (R. t. osborni), Stone's caribou (R. t. stonei), the Rocky Mountain caribou (R. t. fortidens) and the Selkirk Mountains caribou (R. t. montanus) are all montane. The extinct insular Queen Charlotte Islands caribou (R. t. dawsoni), lived on Graham Island in Haida Gwaii (formerly known as the Queen Charlotte Islands).

 

The boreal woodland caribou (R. t. caribou), lives in the boreal forest of northeastern Canada: the Labrador or Ungava caribou of northern Quebec and northern Labrador (R. t. caboti), and the Newfoundland caribou of Newfoundland (R. t. terranovae) have been found to be genetically in the woodland caribou lineage.

 

In Eurasia, both wild and domestic reindeer are distributed across the tundra and into the taiga. Eurasian mountain reindeer (R. t. tarandus) are close to North American caribou genetically and visually, but with sufficient differences to warrant division into two species. The unique, insular Svalbard reindeer inhabits the Svalbard Archipelago. The Finnish forest reindeer (R. t. fennicus) is spottily distributed in the coniferous forest zones from Finland to east of Lake Baikal: the Siberian forest reindeer (R. t. valentinae, formerly called the Busk Mountains reindeer (R. t. buskensis) by American taxonomists) occupies the Altai and Ural Mountains.

 

Male ("bull") and female ("cow") reindeer can grow antlers annually, although the proportion of females that grow antlers varies greatly between populations. Antlers are typically larger on males. Antler architecture varies by species and subspecies and, together with pelage differences, can often be used to distinguish between species and subspecies (see illustrations in Geist, 1991 and Geist, 1998).

 

Status

About 25,000 mountain reindeer (R. t. tarandus) still live in the mountains of Norway, notably in Hardangervidda. In Sweden there are approximately 250,000 reindeer in herds managed by Sami villages. Russia manages 19 herds of Siberian tundra reindeer (R. t. sibiricus) that total about 940,000. The Taimyr herd of Siberian tundra reindeer is the largest wild reindeer herd in the world, varying between 400,000 and 1,000,000; it is a metapopulation consisting of several subpopulations — some of which are phenotypically different — with different migration routes and calving areas. The Kamchatkan reindeer (R. t. phylarchus), a forest subspecies, formerly included reindeer west of the Sea of Okhotsk which, however, are indistinguishable genetically from the Jano-Indigirka, East Siberian taiga and Chukotka populations of R. t. sibiricus. Siberian tundra reindeer herds have been in decline but are stable or increasing since 2000.

 

Insular (island) reindeer, classified as the Novaya Zemlya reindeer (R. t. pearsoni) occupy several island groups: the Novaya Zemlya Archipelago (about 5,000 animals at last count, but most of these are either domestic reindeer or domestic-wild hybrids), the New Siberia Archipelago (about 10,000 to 15,000), and Wrangel Island (200 to 300 feral domestic reindeer).

 

What was once the second largest herd is the migratory Labrador caribou (R. t. caboti)[9] George River herd in Canada, with former variations between 28,000 and 385,000. As of January 2018, there are fewer than 9,000 animals estimated to be left in the George River herd, as reported by the Canadian Broadcasting Corporation. The New York Times reported in April 2018 of the disappearance of the only herd of southern mountain woodland caribou in the contiguous United States, with an expert calling it "functionally extinct" after the herd's size dwindled to a mere three animals. After the last individual, a female, was translocated to a wildlife rehabilitation center in Canada, caribou were considered extirpated from the contiguous United States. The Committee on Status of Endangered Wildlife in Canada (COSEWIC) classified both the Southern Mountain population DU9 (R. t. montanus) and the Central Mountain population DU8 (R. t. fortidens) as Endangered and the Northern Mountain population DU7 (R. t. osborni) as Threatened.

 

Some species and subspecies are rare and three subspecies have already become extinct: the Queen Charlotte Islands caribou (R. t. dawsoni) from western Canada, the Sakhalin reindeer (R. t. setoni) from Sakhalin and the East Greenland caribou from eastern Greenland, although some authorities believe that the latter, R. t. eogroenlandicus Degerbøl, 1957, is a junior synonym of the Peary caribou Historically, the range of the sedentary boreal woodland caribou covered more than half of Canada and into the northern states of the contiguous United States from Maine to Washington. Boreal woodland caribou have disappeared from most of their original southern range and were designated as Threatened in 2002 by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). Environment Canada reported in 2011 that there were approximately 34,000 boreal woodland caribou in 51 ranges remaining in Canada (Environment Canada, 2011b), although those numbers included montane populations classified by Harding (2022) into subspecies of the Arctic caribou. Siberian tundra reindeer herds are also in decline, and Rangifer as a whole is considered to be Vulnerable by the IUCN.

 

Naming

Charles Hamilton Smith is credited with the name Rangifer for the reindeer genus, which Albertus Magnus used in his De animalibus, fol. Liber 22, Cap. 268: "Dicitur Rangyfer quasi ramifer". This word may go back to the Sámi word raingo. Carl Linnaeus chose the word tarandus as the specific epithet, making reference to Ulisse Aldrovandi's Quadrupedum omnium bisulcorum historia fol. 859–863, Cap. 30: De Tarando (1621). However, Aldrovandi and Conrad Gessner thought that rangifer and tarandus were two separate animals, In any case, the tarandos name goes back to Aristotle and Theophrastus.

 

The use of the terms reindeer and caribou for essentially the same animal can cause confusion, but the International Union for Conservation of Nature clearly delineates the issue: "Reindeer is the European name for the species of Rangifer, while in North America, Rangifer species are known as Caribou." The word reindeer is an anglicized version of the Old Norse words hreinn (“reindeer”) and dýr (“animal”) and has nothing to do with reins. The word caribou comes through French, from the Mi'kmaq qalipu, meaning "snow shoveler", and refers to its habit of pawing through the snow for food.

 

Because of its importance to many cultures, Rangifer and some of its species and subspecies have names in many languages. Inuvaluit of the western Canadian Arctic and Inuit of the eastern Canadian Arctic, who speak different dialects of Inuktitut, both call the barren-ground caribou tuktu. The Wekʼèezhìi people, a Dene (Athapascan) group, call the Arctic caribou ekwǫ̀ and the boreal woodland caribou tǫdzı. The Gwichʼin (also a Dene group) have over 24 distinct caribou-related words.

 

Reindeer are also called tuttu by the Greenlandic Inuit and hreindýr, sometimes rein, by the Icelanders.

 

Evolution

The "glacial-interglacial cycles of the upper Pleistocene had a major influence on the evolution" of Rangifer species and other Arctic and sub-Arctic species. Isolation of tundra-adapted species Rangifer in Last Glacial Maximum refugia during the last glacial – the Wisconsin glaciation in North America and the Weichselian glaciation in Eurasia – shaped "intraspecific genetic variability" particularly between the North American and Eurasian parts of the Arctic.

 

Reindeer/caribou (Rangifer) are in the subfamily Odocoileinae, along with roe deer (Capreolus), Eurasian elk/moose (Alces), and water deer (Hydropotes). These antlered cervids split from the horned ruminants Bos (cattle and yaks), Ovis (sheep) and Capra (goats) about 36 million years ago. The Eurasian clade of Odocoileinae (Capreolini, Hydropotini and Alcini) split from the New World tribes of Capreolinae (Odocoileini and Rangiferini) in the Late Miocene, 8.7–9.6 million years ago. Rangifer “evolved as a mountain deer, ...exploiting the subalpine and alpine meadows...”. Rangifer originated in the Late Pliocene and diversified in the Early Pleistocene, a 2+ million-year period of multiple glacier advances and retreats. Several named Rangifer fossils in Eurasia and North America predate the evolution of modern tundra reindeer.

 

Archaeologists distinguish “modern” tundra reindeer and barren-ground caribou from primitive forms — living and extinct — that did not have adaptations to extreme cold and to long distance migration. They include a broad, high muzzle to increase the volume of the nasal cavity to warm and moisten the air before it enters the throat and lungs, bez tines set close to the brow tines, distinctive coat patterns, short legs and other adaptations for running long distances, and multiple behaviors suited to tundra, but not to forest (such as synchronized calving and aggregation during rutting and post-calving). As well, many genes, including those for vitamin D metabolism, fat metabolism, retinal development, circadian rhythm, and tolerance to cold temperatures, are found in tundra caribou that are lacking or rudimentary in forest types. For this reason, forest-adapted reindeer and caribou could not survive in tundra or polar deserts. The oldest undoubted Rangifer fossil is from Omsk, Russia, dated to 2.1-1.8 Ma. The oldest North American Rangifer fossil is from the Yukon, 1.6 million years before present (BP). A fossil skull fragment from Süßenborn, Germany, R. arcticus stadelmanni, (which is probably misnamed) with “rather thin and cylinder-shaped” antlers, dates to the Middle Pleistocene (Günz) Period, 680,000-620,000 BP. Rangifer fossils become increasingly frequent in circumpolar deposits beginning with the Riss glaciations, the second youngest of the Pleistocene Epoch, roughly 300,000–130,000 BP. By the 4-Würm period (110,000–70,000 to 12,000–10,000 BP), its European range was extensive, supplying a major food source for prehistoric Europeans. North American fossils outside of Beringia that predate the Last Glacial Maximum (LGM) are of Rancholabrean age (240,000–11,000 years BP) and occur along the fringes of the Rocky Mountain and Laurentide ice sheets as far south as northern Alabama; and in Sangamonian deposits (~100,000 years BP) from western Canada.

 

A R. t. pearyi-sized caribou occupied Greenland before and after the LGM and persisted in a relict enclave in northeastern Greenland until it went extinct about 1900 (see discussion of R. t. eogroenlandicus below). Archaeological excavations showed that larger barren-ground-sized caribou appeared in western Greenland about 4,000 years ago.

 

The late Valerius Geist (1998) dates the Eurasian reindeer radiation dates to the large Riss glaciation (347,000 to 128,000 years ago), based on the Norwegian-Svalbard split 225,000 years ago. Finnish forest reindeer (R. t. fennicus) likely evolved from Cervus [Rangifer] geuttardi Desmarest, 1822, a reindeer that adapted to forest habitats in Eastern Europe as forests expanded during an interglacial period before the LGM (the Würmian or Weichsel glaciation);. The fossil species geuttardi was later replaced by R. constantini, which was adapted for grasslands, in a second immigration 19,000–20,000 years ago when the LGM turned its forest habitats into tundra, while fennicus survived in isolation in southwestern Europe. R. constantini was then replaced by modern tundra/barren-ground caribou adapted to extreme cold, probably in Beringia, before dispersing west (R. t. tarandus in the Scandinavian mountains and R. t. sibiricus across Siberia) and east (R. t. arcticus in the North American Barrenlands) when rising seas isolated them. Likewise in North America, DNA analysis shows that woodland caribou (R. caribou) diverged from primitive ancestors of tundra/barren-ground caribou not during the LGM, 26,000–19,000 years ago, as previously assumed, but in the Middle Pleistocene around 357,000 years ago. At that time, modern tundra caribou had not even evolved. Woodland caribou are likely more related to extinct North American forest caribou than to barren-ground caribou. For example, the extinct caribou Torontoceros [Rangifer] hypogaeus, had features (robust and short pedicles, smooth antler surface, and high position of second tine) that relate it to forest caribou.

 

Humans started hunting reindeer in both the Mesolithic and Neolithic Periods, and humans are today the main predator in many areas. Norway and Greenland have unbroken traditions of hunting wild reindeer from the Last Glacial Period until the present day. In the non-forested mountains of central Norway, such as Jotunheimen, it is still possible to find remains of stone-built trapping pits, guiding fences and bow rests, built especially for hunting reindeer. These can, with some certainty, be dated to the Migration Period, although it is not unlikely that they have been in use since the Stone Age.

 

Cave paintings by ancient Europeans include both tundra and forest types of reindeer.

 

A 2022 study of ancient environmental DNA from the Early Pleistocene (2 million years ago) Kap Kobenhavn Formation of northern Greenland identified preserved DNA fragments of Rangifer, identified as basal but potentially ancestral to modern reindeer. This suggests that reindeer have inhabited Greenland since at least the Early Pleistocene. Around this time, northern Greenland was 11–19 °C warmer than the Holocene, with a boreal forest hosting a species assemblage with no modern analogue. These are among the oldest DNA fragments ever sequenced.

 

Taxonomy

Carl Linnaeus in 1758 named the Eurasian tundra species Cervus tarandus, the genus Rangifer being credited to Smith, 1827.

 

Rangifer has had a convoluted history because of the similarity in antler architecture (brow tines asymmetrical and often palmate, bez tines, a back tine sometimes branched, and branched at the distal end, often palmate). Because of individual variability, early taxonomists were unable to discern consistent patterns among populations, nor could they, examining collections in Europe, appreciate the difference in habitats and the differing function they imposed on antler architecture. For example, woodland caribou males, rutting in boreal forest where only a few females can be found, collect harems and defend them against other males, for which they have short, straight, strong, much-branched antlers, beams flattened in cross-section, designed for combat — and not too large, so as not to impede them in forested winter ranges. By contrast, modern tundra caribou (see Evolution above) have synchronized calving as a predator-avoidance strategy, which requires large rutting aggregations. Males cannot defend a harem because, while he was busy fighting, they would disappear into the mass of the herd. Males therefore tend individual females; their fights are infrequent and brief. Their antlers are thin, beams round in cross-section, sweep back and then forward with a cluster of branches at the top; these are designed more for visual stimulation of the females. Their bez tines are set low, just above the brow tine, which is vertically flattened to protect the eyes while the buck "threshes" low brush, a courtship display. The low bez tines help the wide flat brow tines dig craters in the hard-packed tundra snow for forage, for which reason brow tines are often called "shovels" in North America and "ice tines" in Europe. The differences in antler architecture reflect fundamental differences in ecology and behavior, and in turn deep divisions in ancestry that were not apparent to the early taxonomists.

 

Similarly, working on museum collections where skins were often faded and in poor states of preservation, early taxonomists could not readily perceive differences in coat patterns that are consistent within a subspecies, but variable among them. Geist calls these "nuptial" characteristics: sexually selected characters that are highly conserved and diagnostic among subspecies.

 

Towards the end of the 19th century, national museums began sending out biological exploration expeditions and collections accumulated. Taxonomists, usually working for the museums began naming subspecies more rigorously, based on statistical differences in detailed cranial, dental and skeletal measurements than antlers and pelage, supplemented by better knowledge of differences in ecology and behavior. From 1898 to 1937, mammalogists named 12 new species (other than barren-ground and woodland, which had been named earlier) of caribou in Canada and Alaska, and three new species and nine new subspecies in Eurasia, each properly described according to the evolving rules of zoological nomenclature, with type localities designated and type specimens deposited in museums.

 

In the mid-20th century, as definitions of "species" evolved, mammalogists in Europe and North America made all Rangifer species conspecific with R. tarandus, and synonymized most of the subspecies. Banfield's often-cited A Revision of the Reindeer and Caribou, Genus Rangifer (1961), eliminated R. t. caboti (the Labrador caribou), R. t. osborni (Osborn's caribou — from British Columbia) and R. t. terranovae (the Newfoundland caribou) as invalid and included only barren-ground caribou, renamed as R. t. groenlandicus (formerly R. arcticus) and woodland caribou as R. t. caribou. However, Banfield made multiple errors, eliciting a scathing review by Ian McTaggart-Cowan in 1962 Most authorities continued to consider all or most subspecies valid; some were quite distinct. In his chapter in the authoritative 2005 reference work Mammal Species of the World, referenced by the American Society of Mammalogists, English zoologist Peter Grubb agreed with Valerius Geist, a specialist on large mammals, that these subspecies were valid (i.e., before the recent revision): In North America, R. t. caboti, R. t. caribou, R. t. dawsoni, R. t. groenlandicus, R. t. osborni, R. t. pearyi, and R. t. terranovae; and in Eurasia, R. t. tarandus, R. t. buskensis (called R. t. valentinae in Europe; see below), R. t. phylarchus, R. t. pearsoni, R. t. sibiricus and R. t. platyrhynchus. These subspecies were retained in the 2011 replacement work Handbook of Mammals of the World Vol. 2: Hoofed Mammals.[8] Most Russian authors also recognized R. t. angustirostris, a forest reindeer from east of Lake Baikal.

 

However, since 1991, many genetic studies have revealed deep divergence between modern tundra reindeer and woodland caribou. Geist (2007) and others continued arguing that the woodland caribou was incorrectly classified, noting that "true woodland caribou, the uniformly dark, small-maned type with the frontally emphasized, flat-beamed antlers", is "scattered thinly along the southern rim of North American caribou distribution". He affirms that the "true woodland caribou is very rare, in very great difficulties and requires the most urgent of attention."

 

In 2011, noting that the former classifications of Rangifer tarandus, either with prevailing taxonomy on subspecies, designations based on ecotypes, or natural population groupings, failed to capture "the variability of caribou across their range in Canada" needed for effective subspecies conservation and management, COSEWIC developed Designatable Unit (DU) attribution, an adaptation of "evolutionary significant units". The 12 designatable units for caribou in Canada (that is, excluding Alaska and Greenland) based on ecology, behavior and, importantly, genetics (but excluding morphology and archaeology) essentially followed the previously-named subspecies distributions, without naming them as such, plus some ecotypes. Ecotypes are not phylogenetically based and cannot substitute for taxonomy.

 

Meanwhile, genetic data continued to accumulate, revealing sufficiently deep divisions to easily separate Rangifer back into six previously named species and to resurrect several previously named subspecies. Molecular data showed that the Greenland caribou (R. t. groenlandicus) and the Svalbard reindeer (R. t. platyrhynchus), although not closely related to each other, were the most genetically divergent among Rangifer clades; that modern (see Evolution above) Eurasian tundra reindeer (R. t. tarandus and R. t. sibiricus) and North American barren-ground caribou (R. t. arcticus), although sharing ancestry, were separable at the subspecies level; that Finnish forest reindeer (R. t. fennicus) clustered well apart from both wild and domestic tundra reindeer and that boreal woodland caribou (R. t. caribou) were separable from all others. Meanwhile, archaeological evidence was accumulating that Eurasian forest reindeer descended from an extinct forest-adapted reindeer and not from tundra reindeer; since they do not share a direct common ancestor, they cannot be conspecific. Similarly, woodland caribou diverged from the ancestors of Arctic caribou before modern barren-ground caribou had evolved, and were more likely related to extinct North American forest reindeer. Lacking a direct shared ancestor, barren-ground and woodland caribou cannot be conspecific.

 

Molecular data also revealed that the four western Canadian montane ecotypes are not woodland caribou: they share a common ancestor with modern barren-ground caribou/tundra reindeer, but distantly, having diverged > 60,000 years ago — before the modern ecotypes had evolved their cold- and darkness-adapted physiologies and mass-migration and aggregation behaviors (see Evolution above). Before Banfield (1961), taxonomists using cranial, dental and skeletal measurements had unequivocally allied these western montane ecotypes with barren-ground caribou, naming them (as in Osgood 1909[85] Murie, 1935 and Anderson 1946, among others) R. t. stonei, R. t. montanus, R. t. fortidens and R. t. osborni, respectively, and this phylogeny was confirmed by genetic analysis.

 

DNA also revealed three unnamed clades that, based on genetic distance, genetic divergence and shared vs. private haplotypes and alleles, together with ecological and behavioral differences, may justify separation at the subspecies level: the Atlantic-Gaspésie caribou (COSEWIC DU11), an eastern montane ecotype of the boreal woodland caribou, and the Baffin Island caribou. Neither one of these clades has yet been formally described or named.

 

Jenkins et al. (2012) said that "[Baffin Island] caribou are unique compared to other Barrenground herds, as they do not overwinter in forested habitat, nor do all caribou undertake long seasonal migrations to calving areas." It also shares a mtDNA haplotype with Labrador caribou, in the North American lineage (i.e., woodland caribou). Røed et al. (1991) had noted:

 

Among Baffin Island caribou the TFL2 allele was the most common allele (p=0.521), while this allele was absent, or present in very low frequencies, in other caribou populations , including the Canadian barren-ground caribou from the Beverly herd. A large genetic difference between Baffin Island caribou and the Beverly herd was also indicated by eight alleles found in the Beverly herd which were absent from the Baffin Island samples.

 

Jenkins et al. (2018) also reported genetic distinctiveness of Baffin Island caribou from all other barren-ground caribou; its genetic signature was not found on the mainland or on other islands; nor were Beverly herd (the nearest mainly barren-ground caribou) alleles present in Baffin Island caribou, evidence of reproductive isolation.

 

These advances in Rangifer genetics were brought together with previous morphological-based descriptions, ecology, behavior and archaeology to propose a new revision of the genus.

 

The scientific name Tarandus rangifer buskensis Millais, 1915 (the Busk Mountains reindeer) was selected as the senior synonym to R. t. valentinae Flerov, 1933, in Mammal Species of the World but Russian authors do not recognize Millais and Millais' articles in a hunting travelogue, The Gun at Home and Abroad, seem short of a taxonomic authority.

 

The scientific name groenlandicus is fraught with problems. Edwards (1743) illustrated and claimed to have seen a male specimen (“head of perfect horns...”) from Greenland and said that a Captain Craycott had brought a live pair from Greenland to England in 1738. He named it Capra groenlandicus, Greenland reindeer. Linnaeus, in the 12th edition of Systema naturae, gave grœnlandicus as a synonym for Cervus tarandus. Borowski disagreed (and again changed the spelling), saying Cervus grönlandicus was morphologically distinct from Eurasian tundra reindeer. Baird placed it under the genus Rangifer as R. grœnlandicus. It went back and forth as a full species or subspecies of the barren-ground caribou (R. arcticus) or a subspecies of the tundra reindeer (R. tarandus), but always as the Greenland reindeer/caribou. Taxonomists consistently documented morphological differences between Greenland and other caribou/reindeer in cranial measurements, dentition, antler architecture, etc. Then Banfield (1961) in his famously flawed revision, gave the name groenlandicus to all the barren-ground caribou in North America, Greenland included, because groenlandicus pre-dates Richardson’s R. arctus,. However, because genetic data shows the Greenland caribou to be the most distantly related of any caribou to all the others (genetic distance, FST = 44%, whereas most cervid (deer family) species have a genetic distance of 2% to 5%)--as well as behavioral and morphological differences—a recent revision returned it to species status as R. groenlandicus. Although it has been assumed that the larger caribou that appeared in Greenland 4,000 years ago originated from Baffin Island (itself unique; see Taxonomy above), a reconstruction of LGM glacial retreat and caribou advance (Yannic et al. 2013) shows colonization by NAL lineage caribou more likely. Their PCA and tree diagrams show Greenland caribou clustering outside of the Beringian-Eurasian lineage.

 

The scientific name R. t. granti has a very interesting history. Allen (1902) named it as a distinct species, R. granti, from the "western end of Alaska Peninsula, opposite Popoff Island" and noting that:

 

Rangifer granti is a representative of the Barren Ground group of Caribou, which includes R. arcticus of the Arctic Coast and R. granlandicus of Greenland. It is not closely related to R. stonei of the Kenai Peninsula, from which it differs not only in its very much smaller size, but in important cranial characters and in coloration. ...The external and cranial differences between R. granti and the various forms of the Woodland Caribou are so great in almost every respect that no detailed comparison is necessary. ...According to Mr. Stone, Rangifer granti inhabits the " barren land of Alaska Peninsula, ranging well up into the mountains in summer, but descending to the lower levels in winter, generally feeding on the low flat lands near the coast and in the foothills...As regards cranial characters no comparison is necessary with R. montanus or with any of the woodland forms."

 

Osgood and Murie (1935), agreeing with granti's close relationship with the barren-ground caribou, brought it under R. arcticus as a subspecies, R. t. granti. Anderson (1946) and Banfield (1961), based on statistical analysis of cranial, dental and other characters, agreed. But Banfield (1961) also synonymized Alaska's large R. stonei with other mountain caribou of British Columbia and the Yukon as invalid subspecies of woodland caribou, then R. t. caribou. This left the small, migratory barren-ground caribou of Alaska and the Yukon, including the Porcupine caribou herd, without a name, which Banfield rectified in his 1974 Mammals of Canada by extending to them the name "granti". The late Valerius Geist (1998), in the only error in his whole illustrious career, re-analyzed Banfield's data with additional specimens found in an unpublished report he cites as "Skal, 1982", but was "not able to find diagnostic features that could segregate this form from the western barren ground type." But Skal 1982 had included specimens from the eastern end of the Alaska Peninsula and the Kenai Peninsula, the range of the larger Stone's caribou. Later, geneticists comparing barren-ground caribou of Alaska with those of mainland Canada found little difference and they all became the former R. t. groenlandicus (now R. t. arcticus). R. t. granti was lost in the oblivion of invalid taxonomy until Alaskan researchers sampled some small, pale caribou from the western end of the Alaska Peninsula, their range enclosing the type locality designated by Allen (1902) and found them to be genetically distinct from all other caribou in Alaska. Thus, granti was rediscovered, its range restricted to that originally described.

 

Stone's caribou (R. t. stonei), a large montane type, was described from the Kenai Peninsula (where, apparently, it was never common except in years of great abundance), the eastern end of the Alaska Peninsula, and mountains throughout southern and eastern Alaska. It was placed under R. arcticus as a subspecies, R. t. stonei, and later synonymised as noted above. The same genetic analyses mentioned above for R. t. granti resulted in resurrecting R. t. stonei as well.

 

The Sakhalin reindeer (R. t. setoni), endemic to Sakhalin, was described as Rangifer tarandus setoni Flerov, 1933, but Banfield (1961) brought it under R. t. fennicus as a junior synonym. The wild reindeer on the island are apparently extinct, having been replaced by domestic reindeer.

 

Some of the Rangifer species and subspecies may be further divided by ecotype depending on several behavioral factors – predominant habitat use (northern, tundra, mountain, forest, boreal forest, forest-dwelling, woodland, woodland (boreal), woodland (migratory) or woodland (mountain), spacing (dispersed or aggregated) and migration patterns (sedentary or migratory). North American examples of this are the Torngat Mountain population DU10, an ecotype of R. t. caboti; a recently discovered and unnamed clade between the Mackenzie River and Great Bear Lake of Beringian-Eurasian lineage, an ecotype of R. t. osborni; the Atlantic-Gaspésie population DU11, an eastern montane ecotype of the boreal woodland caribou (R. t. caribou); the Baffin Island caribou, an ecotype of the barren-ground caribou (R. t. arcticus); and the Dolphin-Union “herd”, another ecotype of R. t. arcticus. The last three of these likely qualify as subspecies, but they have not yet been formally described or named.

 

Physical characteristics

Naming in this and following sections follows the taxonomy in the authoritative 2011 reference work Handbook of Mammals of the World Vol. 2: Hoofed Mammals.

 

Antlers

In most cervid species, only males grow antlers; the reindeer is the only cervid species in which females also grow them normally. Androgens play an essential role in the antler formation of cervids. The antlerogenic genes in reindeer have more sensitivity to androgens in comparison with other cervids.

 

There is considerable variation among species and subspecies in the size of the antlers (e.g., they are rather small and spindly in the northernmost species and subspecies), but on average the bull's antlers are the second largest of any extant deer, after those of the male moose. In the largest subspecies, the antlers of large bulls can range up to 100 cm (39 in) in width and 135 cm (53 in) in beam length. They have the largest antlers relative to body size among living deer species.[116] Antler size measured in number of points reflects the nutritional status of the reindeer and climate variation of its environment. The number of points on male reindeer increases from birth to 5 years of age and remains relatively constant from then on.  "In male caribou, antler mass (but not the number of tines) varies in concert with body mass." While antlers of male woodland caribou are typically smaller than those of male barren-ground caribou, they can be over 1 m (3 ft 3 in) across. They are flattened in cross-section, compact and relatively dense.[36] Geist describes them as frontally emphasized, flat-beamed antlers. Woodland caribou antlers are thicker and broader than those of the barren-ground caribou and their legs and heads are longer. Quebec-Labrador male caribou antlers can be significantly larger and wider than other woodland caribou. Central barren-ground male caribou antlers are perhaps the most diverse in configuration and can grow to be very high and wide. Osborn's caribou antlers are typically the most massive, with the largest circumference measurements.

 

The antlers' main beams begin at the brow "extending posterior over the shoulders and bowing so that the tips point forward. The prominent, palmate brow tines extend forward, over the face." The antlers typically have two separate groups of points, lower and upper.

 

Antlers begin to grow on male reindeer in March or April and on female reindeer in May or June. This process is called antlerogenesis. Antlers grow very quickly every year on the bulls. As the antlers grow, they are covered in thick velvet, filled with blood vessels and spongy in texture. The antler velvet of the barren-ground caribou and the boreal woodland caribou is dark chocolate brown. The velvet that covers growing antlers is a highly vascularised skin. This velvet is dark brown on woodland or barren-ground caribou and slate-grey on Peary caribou and the Dolphin-Union caribou herd. Velvet lumps in March can develop into a rack measuring more than a meter in length (3 ft) by August.

  

A R. tarandus skull

When the antler growth is fully grown and hardened, the velvet is shed or rubbed off. To the Inuit, for whom the caribou is a "culturally important keystone species", the months are named after landmarks in the caribou life cycle. For example, amiraijaut in the Igloolik region is "when velvet falls off caribou antlers."

 

Male reindeer use their antlers to compete with other males during the mating season. Butler (1986) showed that the social requirements of caribou females during the rut determines the mating strategies of males and, consequently, the form of male antlers. In describing woodland caribou, which have a harem-defense mating system, SARA wrote, "During the rut, males engage in frequent and furious sparring battles with their antlers. Large males with large antlers do most of the mating." Reindeer continue to migrate until the bulls have spent their back fat. By contrast, barren-ground caribou males tend individual females and their fights are brief and much less intense; consequently, their antlers are long, and thin, round in cross-section and less branched and are designed more for show (or sexual attraction) than fighting.

 

In late autumn or early winter after the rut, male reindeer lose their antlers, growing a new pair the next summer with a larger rack than the previous year. Female reindeer keep their antlers until they calve. In the Scandinavian and Arctic Circle populations, old bulls' antlers fall off in late December, young bulls' antlers fall off in the early spring, and cows' antlers fall off in the summer.

 

When male reindeer shed their antlers in early to mid-winter, the antlered cows acquire the highest ranks in the feeding hierarchy, gaining access to the best forage areas. These cows are healthier than those without antlers. Calves whose mothers do not have antlers are more prone to disease and have a significantly higher mortality. Cows in good nutritional condition, for example, during a mild winter with good winter range quality, may grow new antlers earlier as antler growth requires high intake.

  

A R. t. platyrhynchus skull

According to a respected Igloolik elder, Noah Piugaattuk, who was one of the last outpost camp leaders, caribou (tuktu) antlers

 

...get detached every year...Young males lose the velvet from the antlers much more quickly than female caribou even though they are not fully mature. They start to work with their antlers just as soon as the velvet starts to fall off. The young males engage in fights with their antlers towards autumn...soon after the velvet had fallen off they will be red, as they start to get bleached their colour changes...When the velvet starts to fall off the antler is red because the antler is made from blood. The antler is the blood that has hardened; in fact, the core of the antler is still bloody when the velvet starts to fall off, at least close to the base.

 

— Elder Noah Piugaattuk of Igloolik cited in "Tuktu — Caribou" (2002) "Canada's Polar Life"

According to the Igloolik Oral History Project (IOHP), "Caribou antlers provided the Inuit with a myriad of implements, from snow knives and shovels to drying racks and seal-hunting tools. A complex set of terms describes each part of the antler and relates it to its various uses". Currently, the larger racks of antlers are used by Inuit as materials for carving. Iqaluit-based Jackoposie Oopakak's 1989 carving, entitled Nunali, which means "place where people live", and which is part of the permanent collection of the National Gallery of Canada, includes a massive set of caribou antlers on which he has intricately carved the miniaturized world of the Inuit where "Arctic birds, caribou, polar bears, seals, and whales are interspersed with human activities of fishing, hunting, cleaning skins, stretching boots, and travelling by dog sled and kayak...from the base of the antlers to the tip of each branch".

 

Pelt

The color of the fur varies considerably, both between individuals and depending on season and species. Northern populations, which usually are relatively small, are whiter, while southern populations, which typically are relatively large, are darker. This can be seen well in North America, where the northernmost subspecies, the Peary caribou, is the whitest and smallest subspecies of the continent, while the Selkirk Mountains caribou (Southern Mountain population DU9) is the darkest and nearly the largest, only exceeded in size by Osborn's caribou (Northern Mountain population DU7).

 

The coat has two layers of fur: a dense woolly undercoat and a longer-haired overcoat consisting of hollow, air-filled hairs. Fur is the primary insulation factor that allows reindeer to regulate their core body temperature in relation to their environment, the thermogradient, even if the temperature rises to 38 °C (100 °F). In 1913, Dugmore noted how the woodland caribou swim so high out of the water, unlike any other mammal, because their hollow, "air-filled, quill-like hair" acts as a supporting "life jacket".

 

A darker belly color may be caused by two mutations of MC1R. They appear to be more common in domestic reindeer herds.

 

Heat exchange

Blood moving into the legs is cooled by blood returning to the body in a countercurrent heat exchange (CCHE), a highly efficient means of minimizing heat loss through the skin's surface. In the CCHE mechanism, in cold weather, blood vessels are closely knotted and intertwined with arteries to the skin and appendages that carry warm blood with veins returning to the body that carry cold blood causing the warm arterial blood to exchange heat with the cold venous blood. In this way, their legs for example are kept cool, maintaining the core body temperature nearly 30 °C (54 °F) higher with less heat lost to the environment. Heat is thus recycled instead of being dissipated. The "heart does not have to pump blood as rapidly in order to maintain a constant body core temperature and thus, metabolic rate." CCHE is present in animals like reindeer, fox and moose living in extreme conditions of cold or hot weather as a mechanism for retaining the heat in (or out of) the body. These are countercurrent exchange systems with the same fluid, usually blood, in a circuit, used for both directions of flow.

 

Reindeer have specialized counter-current vascular heat exchange in their nasal passages. Temperature gradient along the nasal mucosa is under physiological control. Incoming cold air is warmed by body heat before entering the lungs and water is condensed from the expired air and captured before the reindeer's breath is exhaled, then used to moisten dry incoming air and possibly be absorbed into the blood through the mucous membranes. Like moose, caribou have specialized noses featuring nasal turbinate bones that dramatically increase the surface area within the nostrils.

 

Hooves

The reindeer has large feet with crescent-shaped cloven hooves for walking in snow or swamps. According to the Species at Risk Public Registry (SARA), woodland

 

"Caribou have large feet with four toes. In addition to two small ones, called "dew claws," they have two large, crescent-shaped toes that support most of their weight and serve as shovels when digging for food under snow. These large concave hooves offer stable support on wet, soggy ground and on crusty snow. The pads of the hoof change from a thick, fleshy shape in the summer to become hard and thin in the winter months, reducing the animal's exposure to the cold ground. Additional winter protection comes from the long hair between the "toes"; it covers the pads so the caribou walks only on the horny rim of the hooves."

 

— SARA 2014

Reindeer hooves adapt to the season: in the summer, when the tundra is soft and wet, the footpads become sponge-like and provide extra traction. In the winter, the pads shrink and tighten, exposing the rim of the hoof, which cuts into the ice and crusted snow to keep it from slipping. This also enables them to dig down (an activity known as "cratering") through the snow to their favourite food, a lichen known as reindeer lichen (Cladonia rangiferina).

 

Size

The females (or "cows" as they are often called) usually measure 162–205 cm (64–81 in) in length and weigh 80–120 kg (180–260 lb). The males (or "bulls" as they are often called) are typically larger (to an extent which varies between the different species and subspecies), measuring 180–214 cm (71–84 in) in length and usually weighing 159–182 kg (351–401 lb). Exceptionally large bulls have weighed as much as 318 kg (701 lb). Weight varies drastically between the seasons, with bulls losing as much as 40% of their pre-rut weight.

 

The shoulder height is usually 85 to 150 cm (33 to 59 in), and the tail is 14 to 20 cm (5.5 to 7.9 in) long.

 

The reindeer from Svalbard are the smallest of all. They are also relatively short-legged and may have a shoulder height of as little as 80 cm (31 in), thereby following Allen's rule.

 

Clicking sound

The knees of many species and subspecies of reindeer are adapted to produce a clicking sound as they walk. The sounds originate in the tendons of the knees and may be audible from several hundred meters away. The frequency of the knee-clicks is one of a range of signals that establish relative positions on a dominance scale among reindeer. "Specifically, loud knee-clicking is discovered to be an honest signal of body size, providing an exceptional example of the potential for non-vocal acoustic communication in mammals." The clicking sound made by reindeer as they walk is caused by small tendons slipping over bone protuberances (sesamoid bones) in their feet. The sound is made when a reindeer is walking or running, occurring when the full weight of the foot is on the ground or just after it is relieved of the weight.

 

Eyes

A study by researchers from University College London in 2011 revealed that reindeer can see light with wavelengths as short as 320 nm (i.e. in the ultraviolet range), considerably below the human threshold of 400 nm. It is thought that this ability helps them to survive in the Arctic, because many objects that blend into the landscape in light visible to humans, such as urine and fur, produce sharp contrasts in ultraviolet. It has been proposed that UV flashes on power lines are responsible for reindeer avoiding power lines because "...in darkness these animals see power lines not as dim, passive structures but, rather, as lines of flickering light stretching across the terrain."

 

In 2023, researchers studying reindeer living in Cairngorms National Park, Scotland, suggested that UV visual sensitivity in reindeer helps them detect UV-absorbing lichens against a background of UV-reflecting snows.

 

The tapetum lucidum of Arctic reindeer eyes changes in color from gold in summer to blue in winter to improve their vision during times of continuous darkness, and perhaps enable them to better spot predators.

 

Biology and behaviors

Reindeer have developed adaptations for optimal metabolic efficiency during warm months as well as for during cold months. The body composition of reindeer varies highly with the seasons. Of particular interest is the body composition and diet of breeding and non-breeding females between the seasons. Breeding females have more body mass than non-breeding females between the months of March and September with a difference of around 10 kg (22 lb) more than non-breeding females. From November to December, non-breeding females have more body mass than breeding females, as non-breeding females are able to focus their energies towards storage during colder months rather than lactation and reproduction. Body masses of both breeding and non-breeding females peaks in September. During the months of March through April, breeding females have more fat mass than the non-breeding females with a difference of almost 3 kg (6.6 lb). After this, however, non-breeding females on average have a higher body fat mass than do breeding females.

 

The environmental variations play a large part in reindeer nutrition, as winter nutrition is crucial to adult and neonatal survival rates. Lichens are a staple during the winter months as they are a readily available food source, which reduces the reliance on stored body reserves. Lichens are a crucial part of the reindeer diet; however, they are less prevalent in the diet of pregnant reindeer compared to non-pregnant individuals. The amount of lichen in a diet is found more in non-pregnant adult diets than pregnant individuals due to the lack of nutritional value. Although lichens are high in carbohydrates, they are lacking in essential proteins that vascular plants provide. The amount of lichen in a diet decreases in latitude, which results in nutritional stress being higher in areas with low lichen abundance. 

 

In a study of seasonal light-dark cycles on sleep patterns of female reindeer, researchers performed non-invasive electroencephalography (EEG) on reindeer kept in a stable at the UiT The Arctic University of Norway. The EEG recordings showed that: the more time reindeer spend ruminating, the less time they spend in non-rapid eye movement sleep (NREM sleep); and reindeer's brainwaves during rumination resemble the brainwaves present during NREM sleep. These results suggest that, by reducing the time requirement for NREM sleep, reindeer are able to spend more time feeding during the summer months, when food is abundant.

 

Reproduction and life cycle

Reindeer mate in late September to early November, and the gestation period is about 228–234 days. During the mating season, bulls battle for access to cows. Two bulls will lock each other's antlers together and try to push each other away. The most dominant bulls can collect as many as 15–20 cows to mate with. A bull will stop eating during this time and lose much of his body fat reserves.

 

To calve, "females travel to isolated, relatively predator-free areas such as islands in lakes, peatlands, lake-shores, or tundra." As females select the habitat for the birth of their calves, they are warier than males. Dugmore noted that, in their seasonal migrations, the herd follows a female for that reason. Newborns weigh on average 6 kg (13 lb).[148] In May or June, the calves are born. After 45 days, the calves are able to graze and forage, but continue suckling until the following autumn when they become independent from their mothers.

 

Bulls live four years less than the cows, whose maximum longevity is about 17 years. Cows with a normal body size and who have had sufficient summer nutrition can begin breeding anytime between the ages of 1 and 3 years. When a cow has undergone nutritional stress, it is possible for her to not reproduce for the year. Dominant bulls, those with larger body size and antler racks, inseminate more than one cow a season.

 

Social structure, migration and range

Some populations of North American caribou; for example, many herds in the barren-ground caribou subspecies and some woodland caribou in Ungava and northern Labrador, migrate the farthest of any terrestrial mammal, traveling up to 5,000 km (3,000 mi) a year, and covering 1,000,000 km2 (400,000 sq mi). Other North American populations, the boreal woodland caribou for example, are largely sedentary. The European populations are known to have shorter migrations. Island populations, such as the Novaya Zemlya and Svalbard reindeer and the Peary caribou, make local movements both within and among islands. Migrating reindeer can be negatively affected by parasite loads. Severely infected individuals are weak and probably have shortened lifespans, but parasite levels vary between populations. Infections create an effect known as culling: infected migrating animals are less likely to complete the migration.

 

Normally travelling about 19–55 km (12–34 mi) a day while migrating, the caribou can run at speeds of 60–80 km/h (37–50 mph).[2] Young calves can already outrun an Olympic sprinter when only 1 day old. During the spring migration, smaller herds will group together to form larger herds of 50,000 to 500,000 animals, but during autumn migrations, the groups become smaller and the reindeer begin to mate. During winter, reindeer travel to forested areas to forage under the snow. By spring, groups leave their winter grounds to go to the calving grounds. A reindeer can swim easily and quickly, normally at about 6.5 km/h (4.0 mph) but, if necessary, at 10 km/h (6.2 mph) and migrating herds will not hesitate to swim across a large lake or broad river.

 

The barren-ground caribou form large herds and undertake lengthy seasonal migrations from winter feeding grounds in taiga to spring calving grounds and summer range in the tundra. The migrations of the Porcupine herd of barren-ground caribou are among the longest of any mammal. Greenland caribou, found in southwestern Greenland, are "mixed migrators" and many individuals do not migrate; those that do migrate less than 60 km. Unlike the individual-tending mating system, aggregated rutting, synchronized calving and aggregated post-calving of barren-ground caribou, Greenland caribou have a harem-defense mating system and dispersed calving and they do not aggregate.

 

Although most wild tundra reindeer migrate between their winter range in taiga and summer range in tundra, some ecotypes or herds are more or less sedentary. Novaya Zemlya reindeer (R. t. pearsoni) formerly wintered on the mainland and migrated across the ice to the islands for summer, but only a few now migrate. Finnish forest reindeer (R. t. fennicus) were formerly distributed in most of the coniferous forest zones south of the tree line, including some mountains, but are now spottily distributed within this zone.

 

As an adaptation to their Arctic environment, they have lost their circadian rhythm.

 

Distribution and habitat

Originally, the reindeer was found in Scandinavia, Eastern Europe, Greenland, Russia, Mongolia and northern China north of the 50th latitude. In North America, it was found in Canada, Alaska, and the northern contiguous United States from Maine to Washington. In the 19th century, it was still present in southern Idaho. Even in historical times, it probably occurred naturally in Ireland, and it is believed to have lived in Scotland until the 12th century, when the last reindeer were hunted in Orkney. During the Late Pleistocene Epoch, reindeer occurred further south in North America, such as in Nevada, Tennessee, and Alabama, and as far south as Spain in Europe Today, wild reindeer have disappeared from these areas, especially from the southern parts, where it vanished almost everywhere. Large populations of wild reindeer are still found in Norway, Finland, Siberia, Greenland, Alaska and Canada.

 

According to Grubb (2005), Rangifer is "circumboreal in the tundra and taiga" from "Svalbard, Norway, Finland, Russia, Alaska (USA) and Canada including most Arctic islands, and Greenland, south to northern Mongolia, China (Inner Mongolia), Sakhalin Island, and USA (northern Idaho and Great Lakes region)." Reindeer were introduced to, and are feral in, "Iceland, Kerguelen Islands, South Georgia Island, Pribilof Islands, St. Matthew Island": a free-ranging semi-domesticated herd is also present in Scotland.

 

There is strong regional variation in Rangifer herd size. There are large population differences among individual herds and the size of individual herds has varied greatly since 1970. The largest of all herds (in Taimyr, Russia) has varied between 400,000 and 1,000,000; the second largest herd (at the George River in Canada) has varied between 28,000 and 385,000.

 

While Rangifer is a widespread and numerous genus in the northern Holarctic, being present in both tundra and taiga (boreal forest), by 2013, many herds had "unusually low numbers" and their winter ranges in particular were smaller than they used to be. Caribou and reindeer numbers have fluctuated historically, but many herds are in decline across their range. This global decline is linked to climate change for northern migratory herds and industrial disturbance of habitat for non-migratory herds. Barren-ground caribou are susceptible to the effects of climate change due to a mismatch in the phenological process between the availability of food during the calving period.

 

In November 2016, it was reported that more than 81,000 reindeer in Russia had died as a result of climate change. Longer autumns, leading to increased amounts of freezing rain, created a few inches of ice over lichen, causing many reindeer to starve to death.

 

Diet.

Reindeer are ruminants, having a four-chambered stomach. They mainly eat lichens in winter, especially reindeer lichen (Cladonia rangiferina); they are the only large mammal able to metabolize lichen owing to specialised bacteria and protozoa in their gut. They are also the only animals (except for some gastropods) in which the enzyme lichenase, which breaks down lichenin to glucose, has been found. However, they also eat the leaves of willows and birches, as well as sedges and grasses.

 

Reindeer are osteophagous; they are known to gnaw and partly consume shed antlers as a dietary supplement and in some extreme cases will cannibalise each other's antlers before shedding. There is also some evidence to suggest that on occasion, especially in the spring when they are nutritionally stressed, they will feed on small rodents (such as lemmings), fish (such as the Arctic char (Salvelinus alpinus)), and bird eggs. Reindeer herded by the Chukchis have been known to devour mushrooms enthusiastically in late summer.

 

During the Arctic summer, when there is continuous daylight, reindeer change their sleeping pattern from one synchronised with the sun to an ultradian pattern, in which they sleep when they need to digest food.

 

Predators.

A variety of predators prey heavily on reindeer, including overhunting by people in some areas, which contributes to the decline of populations.

 

Golden eagles prey on calves and are the most prolific hunter on the calving grounds. Wolverines will take newborn calves or birthing cows, as well as (less commonly) infirm adults.

 

Brown bears and polar bears prey on reindeer of all ages but, like wolverines, are most likely to attack weaker animals, such as calves and sick reindeer, since healthy adult reindeer can usually outpace a bear. The gray wolf is the most effective natural predator of adult reindeer and sometimes takes large numbers, especially during the winter. Some gray wolf packs, as well as individual grizzly bears in Canada, may follow and live off of a particular reindeer herd year-round.

 

In 2020, scientists on Svalbard witnessed, and were able to film for the first time, a polar bear attack reindeer, driving one into the ocean, where the polar bear caught up with and killed it. The same bear successfully repeated this hunting technique the next day. On Svalbard, reindeer remains account for 27.3% in polar bear scats, suggesting that they "may be a significant part of the polar bear's diet in that area".

 

Additionally, as carrion, reindeer may be scavenged opportunistically by red and Arctic foxes, various species of eagles, hawks and falcons, and common ravens.

 

Bloodsucking insects, such as mosquitoes, black flies, and especially the reindeer warble fly or reindeer botfly (Hypoderma tarandi) and the reindeer nose botfly (Cephenemyia trompe), are a plague to reindeer during the summer and can cause enough stress to inhibit feeding and calving behaviors. An adult reindeer will lose perhaps about 1 L (0.22 imp gal; 0.26 US gal) of blood to biting insects for every week it spends in the tundra. The population numbers of some of these predators is influenced by the migration of reindeer. Tormenting insects keep caribou on the move, searching for windy areas like hilltops and mountain ridges, rock reefs, lakeshore and forest openings, or snow patches that offer respite from the buzzing horde. Gathering in large herds is another strategy that caribou use to block insects.

 

Reindeer are good swimmers and, in one case, the entire body of a reindeer was found in the stomach of a Greenland shark (Somniosus microcephalus), a species found in the far North Atlantic.

 

Other threats

White-tailed deer (Odocoileus virginianus) commonly carry meningeal worm or brainworm (Parelaphostrongylus tenuis), a nematode parasite that causes reindeer, moose (Alces alces), elk (Cervus canadensis), and mule deer (Odocoileus hemionus) to develop fatal neurological symptoms which include a loss of fear of humans. White-tailed deer that carry this worm are partially immune to it.

 

Changes in climate and habitat beginning in the 20th century have expanded range overlap between white-tailed deer and caribou, increasing the frequency of infection within the reindeer population. This increase in infection is a concern for wildlife managers. Human activities, such as "clear-cutting forestry practices, forest fires, and the clearing for agriculture, roadways, railways, and power lines," favor the conversion of habitats into the preferred habitat of the white-tailed deer – "open forest interspersed with meadows, clearings, grasslands, and riparian flatlands." Towards the end of the Soviet Union, there was increasingly open admission from the Soviet government that reindeer numbers were being negatively affected by human activity, and that this must be remediated especially by supporting reindeer breeding by native herders.

 

Conservation

Current status

While overall widespread and numerous, some reindeer species and subspecies are rare and three subspecies have already become extinct. As of 2015, the IUCN has classified the reindeer as Vulnerable due to an observed population decline of 40% over the last +25 years. According to IUCN, Rangifer tarandus as a species is not endangered because of its overall large population and its widespread range.

 

In North America, the Queen Charlotte Islands caribou and the East Greenland caribou both became extinct in the early 20th century, the Peary caribou is designated as Endangered, the boreal woodland caribou is designated as Threatened and some individual populations are endangered as well. While the barren-ground caribou is not designated as Threatened, many individual herds — including some of the largest — are declining and there is much concern at the local level. Grant's caribou, a small, pale subspecies endemic to the western end of the Alaska Peninsula and the adjacent islands, has not been assessed as to its conservation status.

 

The status of the Dolphin-Union "herd" was upgraded to Endangered in 2017. In NWT, Dolphin-Union caribou were listed as Special Concern under the NWT Species at Risk (NWT) Act (2013).

 

Both the Selkirk Mountains caribou (Southern Mountain population DU9) and the Rocky Mountain caribou (Central Mountain population DU8) are classified as Endangered in Canada in regions such as southeastern British Columbia at the Canada–United States border, along the Columbia and Kootenay Rivers and around Kootenay Lake. Rocky Mountain caribou are extirpated from Banff National Park, but a small population remains in Jasper National Park and in mountain ranges to the northwest into British Columbia. Montane caribou are now considered extirpated in the contiguous United States, including Washington and Idaho. Osborn's caribou (Northern Mountain population DU7) is classified as Threatened in Canada.

 

In Eurasia, the Sakhalin reindeer is extinct (and has been replaced by domestic reindeer) and reindeer on most of the Novaya Zemlya islands have also been replaced by domestic reindeer, although some wild reindeer still persist on the northern islands. Many Siberian tundra reindeer herds have declined, some dangerously, but the Taymir herd remains strong and in total about 940,000 wild Siberian tundra reindeer were estimated in 2010.

 

There is strong regional variation in Rangifer herd size. By 2013, many caribou herds in North America had "unusually low numbers" and their winter ranges in particular were smaller than they used to be. Caribou numbers have fluctuated historically, but many herds are in decline across their range. There are many factors contributing to the decline in numbers.

 

Boreal woodland caribou

Ongoing human development of their habitat has caused populations of boreal woodland caribou to disappear from their original southern range. In particular, boreal woodland caribou were extirpated in many areas of eastern North America in the beginning of the 20th century.

Wikipedia, "Sea elephant" redirects here. For the superfamily of sea slugs, see Pterotracheoidea.

Elephant seals

 

Male and female northern elephant seals

 

Male and female southern elephant seals

Scientific classification Edit this classification

Kingdom:Animalia

Phylum:Chordata

Class:Mammalia

Order:Carnivora

Parvorder:Pinnipedia

Family:Phocidae

Tribe:Miroungini

Muizon, 1981

Genus:Mirounga

Gray, 1827

Type species

Phoca leonina

Species

M. angustirostris

M. leonina

Elephant seals or sea elephants are very large, oceangoing true seals in the genus Mirounga. Both species, the northern elephant seal (M. angustirostris) and the southern elephant seal (M. leonina), were hunted to the brink of extinction for lamp oil by the end of the 19th century, but their numbers have since recovered. Males can weigh up to 4,000 kilograms (8,800 lb). Despite their name, elephant seals aren't closely related to elephants, and the large proboscis/trunk that males of the species possess is an example of convergent evolution.

 

The northern elephant seal, somewhat smaller than its southern relative, ranges over the Pacific coast of the U.S., Canada and Mexico. The most northerly breeding location on the Pacific Coast is at Race Rocks Marine Protected Area, at the southern tip of Vancouver Island in the Strait of Juan de Fuca. The southern elephant seal is found in the Southern Hemisphere on islands such as South Georgia and Macquarie Island, and on the coasts of New Zealand, Tasmania, South Africa, and Argentina in the Peninsula Valdés. In southern Chile, there is a small colony of 120 animals at Jackson Bay (Bahía Jackson) in Admiralty Sound (Seno Almirantazgo) on the southern coast of Isla Grande de Tierra del Fuego.[1]

 

The oldest known unambiguous elephant seal fossils are fragmentary fossils of a member of the tribe Miroungini described from the late Pliocene Petane Formation of New Zealand.[2] Teeth originally identified as representing an unnamed species of Mirounga have been found in South Africa, and dated to the Miocene epoch;[3][4] however, Boessenecker and Churchill (2016) considered these teeth almost certainly to be misidentified toothed whale (odontocete) teeth.[2] The elephant seals evolved in the Pacific Ocean during the Pliocene period.[2][5][6]

 

Elephant seals breed annually and are seemingly habitual to colonies that have established breeding areas.[7]

 

Taxonomy

John Edward Gray established the genus Mirounga in 1827.[8] The generic name Mirounga is a Latinization of miouroung, which is said to have been a term for the seal in an Australian Aboriginal language. However, it is not known which language this represents.[9]

 

Description

Elephant seals are marine mammals of the clade Pinnipedia, which, in Latin, means feather- or fin-footed.[10] Elephant seals are in the family Phocidae (true seals, or earless seals).[11] Earless seals (Phocids) have no outer ear and reduced limbs.[11] The reduction of their limbs helps them be more streamlined and move easily in the water.[10] However, it makes moving on land more difficult because they cannot turn their hind flippers forward to walk like eared seals (Otariidae).[10] Also, the hind flippers of elephant seals have a large surface area, which helps propel them in the water.[10]

 

Elephant seals spend most of their life (90%) underwater in search of food, and can cover 100 kilometres (60 miles) a day when they head out to sea.[11] Newborn elephant seals can weigh up to 36 kilograms (79 pounds) and reach lengths up to 122 cm (4 ft 0 in).[11] Sexual dimorphism is extreme; male elephant seals weigh up to 10 times more than females,[12] and having a prominent proboscis.[11]

 

Elephant seals get their name from the large proboscis of the adult male (bull), reminiscent of an elephant's trunk, and considered a secondary sexual characteristic.[13] The bull's proboscis is used in producing extraordinarily loud roaring noises, especially during mating season. More importantly, however, the nose acts as a sort of rebreather, filled with cavities that reabsorb moisture from their exhalations.[14] This is important during mating season when the seals do not leave the beach to feed, and must conserve body moisture as there is no incoming source of water.

 

They are very much larger than other pinnipeds; southern elephant seal bulls typically reach a length of 5 m (16 ft) and a weight of 3,000 kg (7,000 lb), and are much larger than adult females (cows); some exceptionally large males reach up to 6 m (20 ft) in length and weigh 4,000 kg (9,000 lb); cows typically measure about 3 m (10 ft) and 900 kg (2,000 lb). Northern elephant seal bulls reach a length of 4.3 to 4.8 m (14 to 16 ft) and the heaviest weigh about 2,500 kg (5,500 lb).[15][16]

 

The northern and southern elephant seal can be distinguished by various external features. On average, the southern elephant seal is larger than the northern.[12] Adult male northern elephant seals of tend to have a larger proboscis, and thick chest area with a red coloration, compared to the southern species.[12] Females do not have the large proboscis and can be distinguished between species by looking at their nose characteristics.[12] Southern females tend to have a smaller, blunt nose compared to northern females.[12]

 

Extant species distributions

Genus Mirounga – Gray, 1827 – two species

Common nameScientific name and subspeciesRangeSize and ecologyIUCN status and estimated population

Northern elephant seal

  

Mirounga angustirostris

(Gill, 1866)Eastern Pacific Ocean

Map of rangeSize:

 

Habitat:

 

Diet: LC

  

Southern elephant seal

  

Mirounga leonina

(Linnaeus, 1758)Southern Ocean

Map of rangeSize:

 

Habitat:

 

Diet: LC

  

Physiology

 

Skull of a northern elephant seal

Elephant seals spend up to 80% of their lives in the ocean. They can hold their breath for more than 100 minutes,[17][18] longer than any other noncetacean mammal. Elephant seals regularly dive to 1,550 m (5,090 ft) beneath the ocean's surface;[17] the deepest recorded dives of the two species being 2,388 m (7,835 ft) for a southern elephant seal, and 1,735 m (5,692 ft) for a northern elephant seal.[19][20][21] The average depth of their dives is about 300 to 600 m (1,000 to 2,000 ft), typically for around 20 minutes for females and 60 minutes for males, as they search for their favorite foods, which are skates, rays, squid, octopuses, eels, small sharks and large fish. Their stomachs also often contain gastroliths. They spend only brief amounts of time at the surface to rest between dives (2–3 minutes).[11] Females tend to dive a bit deeper due to their prey source.[11]

  

Male elephant seals fighting for mates

Elephant seals are shielded from extreme cold more by their blubber than by fur. Their hair and outer layers of skin molt in large patches. The skin has to be regrown by blood vessels reaching through the blubber. When molting occurs, the seal is susceptible to the cold, and must rest on land, in a safe place called a "haul out". Northern males and young adults haul out during June to July to molt; northern females and immature seals during April to May.

 

Elephant seals have a very large volume of blood, allowing them to hold a large amount of oxygen for use when diving. They have large sinuses in their abdomens to hold blood and can also store oxygen in their muscles with increased myoglobin concentrations in muscle. In addition, they have a larger proportion of oxygen-carrying red blood cells. These adaptations allow elephant seals to dive to such depths and remain underwater for up to two hours.[22]

 

Unlike some other marine mammals, such as dolphins, elephant seals do not have unihemispheric slow-wave sleep. Instead they sleep deeply for a little less than 20 minutes at the time while sinking through the water to depths measured up to 377 meters. When being near the continental shelf, where the ocean is less deep, they will often reach bottom, which sometimes wakes them up. But more often they continue to sleep on the seabed. On average, they get about two hours of sleep a day over a period of seven months, which is among the lowest amount of sleep of any mammal.[23]

 

They are able to slow down their heartbeat (bradycardia) and divert blood flow from the external areas of the body to important core organs.[11] They can also slow down their metabolism while performing deep dives.[11]

 

Elephant seals have a helpful feature in their bodies known as the countercurrent heat exchanger to help conserve energy and prevent heat loss.[11] In this system, arteries and veins are organized in a way to maintain a constant body temperature by having the cool blood flowing to the heart warmed by blood going to external areas of the animal.[11]

 

Milk produced by elephant seals is remarkably high in milkfat compared to other mammals. After an initially lower state, it rises to over 50% milkfat (human breast milk is about 4% milkfat, and cow milk is about 3.5% milkfat).[24]

 

Adaptations

Elephant seals have large circular eyes that have more rods than cones to help them see in low light conditions when they are diving.[10][11] These seals also possess a structure called the tapetum lucidum, which helps their vision by having light reflected back to the retina to allow more chances for photoreceptors to detect light.[10]

 

Their body is covered in blubber, which helps them keep warm and reduce drag while they are swimming.[11] The shape of their body also helps them maneuver well in the water, but limits their movement on land.[11] Also, elephant seals have the ability to fast for long periods of time while breeding or molting.[11] The turbinate process, another unique adaptation, is very beneficial when these seals are fasting, breeding, molting, or hauling out.[11][further explanation needed] This unique nasal structure recycles moisture when they breathe and helps prevent water loss.[11]

 

Elephant seals have external whiskers called vibrissae to help them locate prey and navigate their environment.[11] The vibrissae are connected to blood vessels, nerves, and muscles making them an important sensing tool.[10]

 

Due to evolutionary changes, their ear has been modified to work extremely well underwater.[10] The structure of the inner ear helps amplify incoming sounds, and allows these seals to have good directional hearing due to the isolation of the inner ear.[10] In addition to these adaptations, tissues in the ear canal allow the pressure in the ear to be adjusted while these seals perform their deep dives.[10]

 

Breeding season

 

Northern Elephant Seal rookery at San Simeon, California.

Males arrive at potential breeding sites in spring, and fast to ensure that they can mate with as many females as possible.[11] Male elephant seals use fighting, vocalisations, and different positions to determine the dominant males.[11][25] By the time males reach eight to nine years of age, they have developed a pronounced long nose, in addition to a chest shield, which is thickened skin in their chest area.[11] They display their dominance by showing their noses, making loud vocalisations, and altering their postures.[11][25] They fight each other by raising themselves and ramming each other with their chests and teeth.[11]

 

By the time females arrive, each dominating male has already established his territory on the beach.[11] Females cluster in groups called harems, which consist of up to 50 females surrounding one alpha male.[11] Outside of these groups, a beta bull is normally roaming around on the beach.[11] The beta bull helps the alpha by preventing other males accessing the females.[11] In return, the beta bull might have an opportunity to mate with one of the females while the alpha is occupied.[11]

 

Birth on average only takes a few minutes, and the mother and pup have a connection due to each other's unique smell and sound.[11] The mothers will fast and nurse up to 28 days, providing their pups with rich milk.[11] For the last two to three days, however, females will be ready to mate, and the dominant males will pounce on the opportunity.[11] Males and females lose up to a third of their body weight during the breeding season.[11] The gestation period for females is 11 months, and the pupping seasons lasts from mid to late summer.[11] The new pups will spend up to 10 additional weeks on land learning how to swim and dive.[11]

 

Life history

The average lifespan of a northern elephant seal is 9 years, while the average lifespan of a southern elephant seal is 21 years.[26] Males reach maturity at five to six years, but generally do not achieve alpha status until the age of eight, with the prime breeding years being between ages 9 and 12. The longest life expectancy of a male northern elephant seal is approximately 14 years.

 

Females begin breeding at age 3–6, and have one pup per breeding attempt.[27] Most adult females breed each year.[28] Breeding success is much lower for first-time mothers relative to experienced breeders.[28] Annual survival probability of adult females is 0.83 for experienced breeding females, but only 0.66 for first-time breeders indicating a significant cost of reproduction.[28] More male pups are produced than female pups in years with warmer sea surface temperature in the northeastern Pacific Ocean.[29]

 

Females and males utilize different feeding strategies in order to maximize their reproductive success. Males feed in benthic regions with more abundant food sources, but also more abundant predators. Females feed in pelagic regions where they are less likely to find prey, but also less likely to be preyed upon. They employ these different strategies because the smaller females require less food, and with at most one pup a year it is also most important for them to have as many breeding seasons as possible in order to maximize reproductive success. On the other hand, males adopt a high risk but high reward strategy in the hopes of gaining as much mass as possible, and thus being able to have one extremely successful breeding season as an alpha.[30]

 

Molting

 

Warning sign seen in South Africa to protect molting seals while hauling out on land

Once a year, elephant seals go through a process called molting where they shed the outer layer of hair and skin.[11] This molting process takes up to a month to complete.[11] When it comes time to molt, they will haul out on land to shed their outer layer, and will not consume any food during this time.[11] The females and juveniles will molt first, followed by the sub adult males, and finally the large mature males.[11]

 

Predators

The main predators of elephant seals are killer whales and great white sharks.[11] Cookiecutter sharks can take bites from their skin.[11]

 

Milk stealing

Sheathbills, Skuas, Western Gulls, and African feral cats have been reported to steal milk from the elephant seals' teats.[31][32][33][34]

 

Status

The IUCN lists both species of elephant seal as being of least concern, although they are still threatened by entanglement in marine debris, fishery interactions, and boat collisions. Though a complete population count of elephant seals is not possible because all age classes are not ashore at the same time, a 2005 study of the California breeding stock estimated approximately 124,000 individuals.[35] The animal is protected in most countries where it lives. In Mexico, the northern elephant seal is protected in the Guadalupe Island Biosphere Reserve where it was rediscovered after being believed to be extinct.[36] Wikipedia

 

A camel (from Latin: camelus and Greek: κάμηλος (kamēlos) from Ancient Semitic: gāmāl) is an even-toed ungulate in the genus Camelus that bears distinctive fatty deposits known as "humps" on its back. Camels have long been domesticated and, as livestock, they provide food (milk and meat) and textiles (fiber and felt from hair). Camels are working animals especially suited to their desert habitat and are a vital means of transport for passengers and cargo. There are three surviving species of camel. The one-humped dromedary makes up 94% of the world's camel population, and the two-humped Bactrian camel makes up 6%. The wild Bactrian camel is a separate species and is now critically endangered.

 

The word camel is also used informally in a wider sense, where the more correct term is "camelid", to include all seven species of the family Camelidae: the true camels (the above three species), along with the "New World" camelids: the llama, the alpaca, the guanaco, and the vicuña, which belong to the separate tribe Lamini. Camelids originated in North America during the Eocene, with the ancestor of modern camels, Paracamelus, migrating across the Bering land bridge into Asia during the late Miocene, around 6 million years ago.

 

Taxonomy

Extant species

Three species are extant:

 

ImageCommon nameScientific nameDistribution

Bactrian camelCamelus bactrianusDomesticated; Central Asia, including the historical region of Bactria.

Dromedary / Arabian camelCamelus dromedariusDomesticated; the Middle East, Sahara Desert, and South Asia; introduced to Australia

Wild Bactrian camelCamelus ferusRemote areas of northwest China and Mongolia

Biology

The average life expectancy of a camel is 40 to 50 years. A full-grown adult dromedary camel stands 1.85 m (6 ft 1 in) at the shoulder and 2.15 m (7 ft 1 in) at the hump. Bactrian camels can be a foot taller. Camels can run at up to 65 km/h (40 mph) in short bursts and sustain speeds of up to 40 km/h (25 mph). Bactrian camels weigh 300 to 1,000 kg (660 to 2,200 lb) and dromedaries 300 to 600 kg (660 to 1,320 lb). The widening toes on a camel's hoof provide supplemental grip for varying soil sediments.

 

The male dromedary camel has an organ called a dulla in his throat, a large, inflatable sac that he extrudes from his mouth when in rut to assert dominance and attract females. It resembles a long, swollen, pink tongue hanging out of the side of the camel's mouth. Camels mate by having both male and female sitting on the ground, with the male mounting from behind. The male usually ejaculates three or four times within a single mating session. Camelids are the only ungulates to mate in a sitting position.

 

Ecological and behavioral adaptations

  

Camel humps store fat, which are used as nourishment when food is scarce. If a camel uses the fat inside the hump, the hump will become limp and droop down

Camels do not directly store water in their humps; they are reservoirs of fatty tissue. When this tissue is metabolized, it yields a greater mass of water than that of the fat processed. This fat metabolization, while releasing energy, causes water to evaporate from the lungs during respiration (as oxygen is required for the metabolic process): overall, there is a net decrease in water.

 

Camels have a series of physiological adaptations that allow them to withstand long periods of time without any external source of water. The dromedary camel can drink as seldom as once every 10 days even under very hot conditions, and can lose up to 30% of its body mass due to dehydration. Unlike other mammals, camels' red blood cells are oval rather than circular in shape. This facilitates the flow of red blood cells during dehydration and makes them better at withstanding high osmotic variation without rupturing when drinking large amounts of water: a 600 kg (1,300 lb) camel can drink 200 L (53 US gal) of water in three minutes.

 

Camels are able to withstand changes in body temperature and water consumption that would kill most other mammals. Their temperature ranges from 34 °C (93 °F) at dawn and steadily increases to 40 °C (104 °F) by sunset, before they cool off at night again. In general, to compare between camels and the other livestock, camels lose only 1.3 liters of fluid intake every day while the other livestock lose 20 to 40 liters per day. Maintaining the brain temperature within certain limits is critical for animals; to assist this, camels have a rete mirabile, a complex of arteries and veins lying very close to each other which utilizes countercurrent blood flow to cool blood flowing to the brain. Camels rarely sweat, even when ambient temperatures reach 49 °C (120 °F). Any sweat that does occur evaporates at the skin level rather than at the surface of their coat; the heat of vaporization therefore comes from body heat rather than ambient heat. Camels can withstand losing 25% of their body weight in water, whereas most other mammals can withstand only about 12–14% dehydration before cardiac failure results from circulatory disturbance.

 

When the camel exhales, water vapor becomes trapped in their nostrils and is reabsorbed into the body as a means to conserve water. Camels eating green herbage can ingest sufficient moisture in milder conditions to maintain their bodies' hydrated state without the need for drinking.

  

Domesticated camel calves lying in sternal recumbency, a position that aids heat loss

The camel's thick coat insulates it from the intense heat radiated from desert sand; a shorn camel must sweat 50% more to avoid overheating. During the summer the coat becomes lighter in color, reflecting light as well as helping avoid sunburn. The camel's long legs help by keeping its body farther from the ground, which can heat up to 70 °C (158 °F). Dromedaries have a pad of thick tissue over the sternum called the pedestal. When the animal lies down in a sternal recumbent position, the pedestal raises the body from the hot surface and allows cooling air to pass under the body.

 

Camels' mouths have a thick leathery lining, allowing them to chew thorny desert plants. Long eyelashes and ear hairs, together with nostrils that can close, form a barrier against sand. If sand gets lodged in their eyes, they can dislodge it using their translucent third eyelid (also known as the nictitating membrane). The camels' gait and widened feet help them move without sinking into the sand.

 

The kidneys and intestines of a camel are very efficient at reabsorbing water. Camels' kidneys have a 1:4 cortex to medulla ratio. Thus, the medullary part of a camel's kidney occupies twice as much area as a cow's kidney. Secondly, renal corpuscles have a smaller diameter, which reduces surface area for filtration. These two major anatomical characteristics enable camels to conserve water and limit the volume of urine in extreme desert conditions. Camel urine comes out as a thick syrup, and camel faeces are so dry that they do not require drying when used to fuel fires.

 

The camel immune system differs from those of other mammals. Normally, the Y-shaped antibody molecules consist of two heavy (or long) chains along the length of the Y, and two light (or short) chains at each tip of the Y. Camels, in addition to these, also have antibodies made of only two heavy chains, a trait that makes them smaller and more durable. These "heavy-chain-only" antibodies, discovered in 1993, are thought to have developed 50 million years ago, after camelids split from ruminants and pigs. Camels suffer from surra caused by Trypanosoma evansi wherever camels are domesticated in the world: 2  and resultantly camels have evolved trypanolytic antibodies as with many mammals. In the future, nanobody/single-domain antibody therapy will surpass natural camel antibodies by reaching locations currently unreachable due to natural antibodies' larger size.: 788  Such therapies may also be suitable for other mammals.: 788  Tran et al. 2009 provides a new reference test for surra (T. evansi) of camel. They use recombinant Invariant Surface Glycoprotein 75 (rISG75, an Invariant Surface Glycoprotein) and ELISA. The Tran test has high test specificity and appears likely to work just as well for T. evansi in other hosts, and for a pan-Trypanozoon test, which would also be useful for T. b. brucei, T. b. gambiense, T. b. rhodesiense, and T. equiperdum.

 

Genetics

The karyotypes of different camelid species have been studied earlier by many groups, but no agreement on chromosome nomenclature of camelids has been reached. A 2007 study flow sorted camel chromosomes, building on the fact that camels have 37 pairs of chromosomes (2n=74), and found that the karyotype consisted of one metacentric, three submetacentric, and 32 acrocentric autosomes. The Y is a small metacentric chromosome, while the X is a large metacentric chromosome.

 

The hybrid camel, a hybrid between Bactrian and dromedary camels, has one hump, though it has an indentation 4–12 cm (1.6–4.7 in) deep that divides the front from the back. The hybrid is 2.15 m (7 ft 1 in) at the shoulder and 2.32 m (7 ft 7 in) tall at the hump. It weighs an average of 650 kg (1,430 lb) and can carry around 400 to 450 kg (880 to 990 lb), which is more than either the dromedary or Bactrian can.

 

According to molecular data, the wild Bactrian camel (C. ferus) separated from the domestic Bactrian camel (C. bactrianus) about 1 million years ago. New World and Old World camelids diverged about 11 million years ago. In spite of this, these species can hybridize and produce viable offspring. The cama is a camel-llama hybrid bred by scientists to see how closely related the parent species are. Scientists collected semen from a camel via an artificial vagina and inseminated a llama after stimulating ovulation with gonadotrophin injections. The cama is halfway in size between a camel and a llama and lacks a hump. It has ears intermediate between those of camels and llamas, longer legs than the llama, and partially cloven hooves. Like the mule, camas are sterile, despite both parents having the same number of chromosomes.

 

Evolution

The earliest known camel, called Protylopus, lived in North America 40 to 50 million years ago (during the Eocene). It was about the size of a rabbit and lived in the open woodlands of what is now South Dakota. By 35 million years ago, the Poebrotherium was the size of a goat and had many more traits similar to camels and llamas. The hoofed Stenomylus, which walked on the tips of its toes, also existed around this time, and the long-necked Aepycamelus evolved in the Miocene. The split between the tribes Camelini, which contains modern camels and Lamini, modern llamas, alpacas, vicuñas, and guanacos, is estimated to have occurred over 16 million years ago.

 

The ancestor of modern camels, Paracamelus, migrated into Eurasia from North America via Beringia during the late Miocene, between 7.5 and 6.5 million years ago. During the Pleistocene, around 3 to 1 million years ago, the North American Camelidae spread to South America as part of the Great American Interchange via the newly formed Isthmus of Panama, where they gave rise to guanacos and related animals. Populations of Paracamelus continued to exist in the North American Arctic into the Early Pleistocene. This creature is estimated to have stood around nine feet (2.7 metres) tall. The Bactrian camel diverged from the dromedary about 1 million years ago, according to the fossil record.

 

The last camel native to North America was Camelops hesternus, which vanished along with horses, short-faced bears, mammoths and mastodons, ground sloths, sabertooth cats, and many other megafauna as part of the Quaternary extinction event, coinciding with the migration of humans from Asia at the end of the Pleistocene, around 13–11,000 years ago.

 

Domestication

Like horses, camels originated in North America and eventually spread across Beringia to Asia. They survived in the Old World, and eventually humans domesticated them and spread them globally. Along with many other megafauna in North America, the original wild camels were wiped out during the spread of the first indigenous peoples of the Americas from Asia into North America, 10 to 12,000 years ago; although fossils have never been associated with definitive evidence of hunting.

 

Most camels surviving today are domesticated. Although feral populations exist in Australia, India and Kazakhstan, wild camels survive only in the wild Bactrian camel population of the Gobi Desert.

 

History

When humans first domesticated camels is disputed. Dromedaries may have first been domesticated by humans in Somalia or South Arabia sometime during the 3rd millennium BC, the Bactrian in central Asia around 2,500 BC, as at Shar-i Sokhta (also known as the Burnt City), Iran. A study from 2016, which genotyped and used world-wide sequencing of modern and ancient mitochondrial DNA (mtDNA), suggested that they were initially domesticated in the southeast Arabian Peninsula, with the Bactrian type later being domesticated around Central Asia.

 

Martin Heide's 2010 work on the domestication of the camel tentatively concludes that humans had domesticated the Bactrian camel by at least the middle of the third millennium somewhere east of the Zagros Mountains, with the practice then moving into Mesopotamia. Heide suggests that mentions of camels "in the patriarchal narratives may refer, at least in some places, to the Bactrian camel", while noting that the camel is not mentioned in relationship to Canaan. Heide and Joris Peters reasserted that conclusion in their 2021 study on the subject.

 

In 2009-2013, excavations in the Timna Valley by Lidar Sapir-Hen and Erez Ben-Yosef discovered what may be the earliest domestic camel bones yet found in Israel or even outside the Arabian Peninsula, dating to around 930 BC. This garnered considerable media coverage, as it is strong evidence that the stories of Abraham, Jacob, Esau, and Joseph were written after this time.

 

The existence of camels in Mesopotamia—but not in the eastern Mediterranean lands—is not a new idea. The historian Richard Bulliet did not think that the occasional mention of camels in the Bible meant that the domestic camels were common in the Holy Land at that time. The archaeologist William F. Albright, writing even earlier, saw camels in the Bible as an anachronism.

 

The official report by Sapir-Hen and Ben-Joseph notes:

 

The introduction of the dromedary camel (Camelus dromedarius) as a pack animal to the southern Levant ... substantially facilitated trade across the vast deserts of Arabia, promoting both economic and social change (e.g., Kohler 1984; Borowski 1998: 112–116; Jasmin 2005). This ... has generated extensive discussion regarding the date of the earliest domestic camel in the southern Levant (and beyond) (e.g., Albright 1949: 207; Epstein 1971: 558–584; Bulliet 1975; Zarins 1989; Köhler-Rollefson 1993; Uerpmann and Uerpmann 2002; Jasmin 2005; 2006; Heide 2010; Rosen and Saidel 2010; Grigson 2012). Most scholars today agree that the dromedary was exploited as a pack animal sometime in the early Iron Age (not before the 12th century [BC])

 

and concludes:

 

Current data from copper smelting sites of the Aravah Valley enable us to pinpoint the introduction of domestic camels to the southern Levant more precisely based on stratigraphic contexts associated with an extensive suite of radiocarbon dates. The data indicate that this event occurred not earlier than the last third of the 10th century [BC] and most probably during this time. The coincidence of this event with a major reorganization of the copper industry of the region—attributed to the results of the campaign of Pharaoh Shoshenq I—raises the possibility that the two were connected, and that camels were introduced as part of the efforts to improve efficiency by facilitating trade.

 

Textiles

Main article: Camel hair

Desert tribes and Mongolian nomads use camel hair for tents, yurts, clothing, bedding and accessories. Camels have outer guard hairs and soft inner down, and the fibers are sorted by color and age of the animal. The guard hairs can be felted for use as waterproof coats for the herdsmen, while the softer hair is used for premium goods. The fiber can be spun for use in weaving or made into yarns for hand knitting or crochet. Pure camel hair is recorded as being used for western garments from the 17th century onwards, and from the 19th century a mixture of wool and camel hair was used.

 

Military uses

Main article: Camel cavalry

By at least 1200 BC the first camel saddles had appeared, and Bactrian camels could be ridden. The first saddle was positioned to the back of the camel, and control of the Bactrian camel was exercised by means of a stick. However, between 500 and 100 BC, Bactrian camels came into military use. New saddles, which were inflexible and bent, were put over the humps and divided the rider's weight over the animal. In the seventh century BC the military Arabian saddle evolved, which again improved the saddle design slightly.

 

Military forces have used camel cavalries in wars throughout Africa, the Middle East, and into the modern-day Border Security Force (BSF) of India (though as of July 2012, the BSF planned the replacement of camels with ATVs). The first documented use of camel cavalries occurred in the Battle of Qarqar in 853 BC. Armies have also used camels as freight animals instead of horses and mules.

 

The East Roman Empire used auxiliary forces known as dromedarii, whom the Romans recruited in desert provinces. The camels were used mostly in combat because of their ability to scare off horses at close range (horses are afraid of the camels' scent), a quality famously employed by the Achaemenid Persians when fighting Lydia in the Battle of Thymbra (547 BC).

 

19th and 20th centuries

A photo of Bulgarian military-transport camels in 1912

A camel caravan of the Bulgarian military during the First Balkan War, 1912

The United States Army established the U.S. Camel Corps, stationed in California, in the 19th century.[19] One may still see stables at the Benicia Arsenal in Benicia, California, where they nowadays serve as the Benicia Historical Museum. Though the experimental use of camels was seen as a success (John B. Floyd, Secretary of War in 1858, recommended that funds be allocated towards obtaining a thousand more camels), the outbreak of the American Civil War in 1861 saw the end of the Camel Corps: Texas became part of the Confederacy, and most of the camels were left to wander away into the desert.

 

France created a méhariste camel corps in 1912 as part of the Armée d'Afrique in the Sahara in order to exercise greater control over the camel-riding Tuareg and Arab insurgents, as previous efforts to defeat them on foot had failed. The Free French Camel Corps fought during World War II, and camel-mounted units remained in service until the end of French rule over Algeria in 1962.

 

In 1916, the British created the Imperial Camel Corps. It was originally used to fight the Senussi, but was later used in the Sinai and Palestine Campaign in World War I. The Imperial Camel Corps comprised infantrymen mounted on camels for movement across desert, though they dismounted at battle sites and fought on foot. After July 1918, the Corps began to become run down, receiving no new reinforcements, and was formally disbanded in 1919.

 

In World War I, the British Army also created the Egyptian Camel Transport Corps, which consisted of a group of Egyptian camel drivers and their camels. The Corps supported British war operations in Sinai, Palestine, and Syria by transporting supplies to the troops.

 

The Somaliland Camel Corps was created by colonial authorities in British Somaliland in 1912; it was disbanded in 1944.

 

Bactrian camels were used by Romanian forces during World War II in the Caucasian region. At the same period the Soviet units operating around Astrakhan in 1942 adopted local camels as draft animals due to shortage of trucks and horses, and kept them even after moving out of the area. Despite severe losses, some of these camels ended up as far west as to Berlin itself.

 

The Bikaner Camel Corps of British India fought alongside the British Indian Army in World Wars I and II.

 

The Tropas Nómadas (Nomad Troops) were an auxiliary regiment of Sahrawi tribesmen serving in the colonial army in Spanish Sahara (today Western Sahara). Operational from the 1930s until the end of the Spanish presence in the territory in 1975, the Tropas Nómadas were equipped with small arms and led by Spanish officers. The unit guarded outposts and sometimes conducted patrols on camelback.

 

21st century competition

At the King Abdulaziz Camel Festival, in Saudi Arabia, thousands of camels are paraded and are judged on their lips and humps. The festival also features camel racing and camel milk tasting and has combined prize money of $57m (£40m). In 2018, 12 camels were disqualified from the beauty contest after it was discovered their owners had tried to improve their camel's good looks with injections of botox, into the animals' lips, noses and jaws. In 2021 over 40 camels were disqualified for acts of tampering and deception in beautifying camels.

 

Food uses

Dairy

Main article: Camel milk

Camel milk is a staple food of desert nomad tribes and is sometimes considered a meal itself; a nomad can live on only camel milk for almost a month.

 

Camel milk can readily be made into yogurt, but can only be made into butter if it is soured first, churned, and a clarifying agent is then added. Until recently, camel milk could not be made into camel cheese because rennet was unable to coagulate the milk proteins to allow the collection of curds. Developing less wasteful uses of the milk, the FAO commissioned Professor J.P. Ramet of the École Nationale Supérieure d'Agronomie et des Industries Alimentaires, who was able to produce curdling by the addition of calcium phosphate and vegetable rennet in the 1990s. The cheese produced from this process has low levels of cholesterol and is easy to digest, even for the lactose intolerant.

 

Camels provide food in the form of meat and milk. Approximately 3.3 million camels and camelids are slaughtered each year for meat worldwide. A camel carcass can provide a substantial amount of meat. The male dromedary carcass can weigh 300–400 kg (661–882 lb), while the carcass of a male Bactrian can weigh up to 650 kg (1,433 lb). The carcass of a female dromedary weighs less than the male, ranging between 250 and 350 kg (550 and 770 lb). The brisket, ribs and loin are among the preferred parts, and the hump is considered a delicacy. The hump contains "white and sickly fat", which can be used to make the khli (preserved meat) of mutton, beef, or camel. On the other hand, camel milk and meat are rich in protein, vitamins, glycogen, and other nutrients making them essential in the diet of many people. From chemical composition to meat quality, the dromedary camel is the preferred breed for meat production. It does well even in arid areas due to its unusual physiological behaviors and characteristics, which include tolerance to extreme temperatures, radiation from the sun, water paucity, rugged landscape and low vegetation. Camel meat is reported to taste like coarse beef, but older camels can prove to be very tough, although camel meat becomes tenderer the more it is cooked.

 

Camel is one of the animals that can be ritually slaughtered and divided into three portions (one for the home, one for extended family/social networks, and one for those who cannot afford to slaughter an animal themselves) for the qurban of Eid al-Adha.

 

The Abu Dhabi Officers' Club serves a camel burger mixed with beef or lamb fat in order to improve the texture and taste. In Karachi, Pakistan, some restaurants prepare nihari from camel meat. Specialist camel butchers provide expert cuts, with the hump considered the most popular.

 

Camel meat has been eaten for centuries. It has been recorded by ancient Greek writers as an available dish at banquets in ancient Persia, usually roasted whole. The Roman emperor Heliogabalus enjoyed camel's heel. Camel meat is mainly eaten in certain regions, including Eritrea, Somalia, Djibouti, Saudi Arabia, Egypt, Syria, Libya, Sudan, Ethiopia, Kazakhstan, and other arid regions where alternative forms of protein may be limited or where camel meat has had a long cultural history. Camel blood is also consumable, as is the case among pastoralists in northern Kenya, where camel blood is drunk with milk and acts as a key source of iron, vitamin D, salts and minerals.

 

A 2005 report issued jointly by the Saudi Ministry of Health and the United States Centers for Disease Control and Prevention details four cases of human bubonic plague resulting from the ingestion of raw camel liver.

 

Australia

Camel meat is also occasionally found in Australian cuisine: for example, a camel lasagna is available in Alice Springs. Australia has exported camel meat, primarily to the Middle East but also to Europe and the US, for many years. The meat is very popular among East African Australians, such as Somalis, and other Australians have also been buying it. The feral nature of the animals means they produce a different type of meat to farmed camels in other parts of the world, and it is sought after because it is disease-free, and a unique genetic group. Demand is outstripping supply, and governments are being urged not to cull the camels, but redirect the cost of the cull into developing the market. Australia has seven camel dairies, which produce milk, cheese and skincare products in addition to meat.

 

Religion

Islam

Main article: Animals in Islam

Muslims consider camel meat halal (Arabic: حلال, 'allowed'). However, according to some Islamic schools of thought, a state of impurity is brought on by the consumption of it. Consequently, these schools hold that Muslims must perform wudhu (ablution) before the next time they pray after eating camel meat. Also, some Islamic schools of thought consider it haram (Arabic: حرام, 'forbidden') for a Muslim to perform Salat in places where camels lie, as it is said to be a dwelling place of the Shaytan (Arabic: شيطان, 'Devil'). According to Abu Yusuf (d.798), the urine of camel may be used for medical treatment if necessary, but according to Abū Ḥanīfah, the drinking of camel urine is discouraged.

 

The Islamic texts contain several stories featuring camels. In the story of the people of Thamud, the prophet Salih miraculously brings forth a naqat (Arabic: ناقة, 'milch-camel') out of a rock. After the prophet Muhammad migrated from Mecca to Medina, he allowed his she-camel to roam there; the location where the camel stopped to rest determined the location where he would build his house in Medina.

 

Judaism

See also: Food and drink prohibitions

According to Jewish tradition, camel meat and milk are not kosher. Camels possess only one of the two kosher criteria; although they chew their cud, they do not possess cloven hooves: "But these you shall not eat among those that bring up the cud and those that have a cloven hoof: the camel, because it brings up its cud, but does not have a [completely] cloven hoof; it is unclean for you."

 

Cultural depictions

What may be the oldest carvings of camels were discovered in 2018 in Saudi Arabia. They were analysed by researchers from several scientific disciplines and, in 2021, were estimated to be 7,000 to 8,000 years old. The dating of rock art is made difficult by the lack of organic material in the carvings that may be tested, so the researchers attempting to date them tested animal bones found associated with the carvings, assessed erosion patterns, and analysed tool marks in order to determine a correct date for the creation of the sculptures. This Neolithic dating would make the carvings significantly older than Stonehenge (5,000 years old) and the Egyptian pyramids at Giza (4,500 years old) and it predates estimates for the domestication of camels.

 

Distribution and numbers

A view into a canyon: many camels gathering around a watering hole

Camels in the Guelta d'Archei, in northeastern Chad

There are approximately 14 million camels alive as of 2010, with 90% being dromedaries. Dromedaries alive today are domesticated animals (mostly living in the Horn of Africa, the Sahel, Maghreb, Middle East and South Asia). The Horn region alone has the largest concentration of camels in the world, where the dromedaries constitute an important part of local nomadic life. They provide nomadic people in Somalia and Ethiopia with milk, food, and transportation.

 

Over one million dromedary camels are estimated to be feral in Australia, descended from those introduced as a method of transport in the 19th and early 20th centuries. This population is growing about 8% per year; it was estimated at around 700,000 in 2008. Representatives of the Australian government have culled more than 100,000 of the animals in part because the camels use too much of the limited resources needed by sheep farmers.

 

A small population of introduced camels, dromedaries and Bactrians, wandered through Southwestern United States after having been imported in the 19th century as part of the U.S. Camel Corps experiment. When the project ended, they were used as draft animals in mines and escaped or were released. Twenty-five U.S. camels were bought and exported to Canada during the Cariboo Gold Rush.

 

The Bactrian camel is, as of 2010, reduced to an estimated 1.4 million animals, most of which are domesticated. The Wild Bactrian camel is a separate species and is the only truly wild (as opposed to feral) camel in the world. The wild camels are critically endangered and number approximately 1400, inhabiting the Gobi and Taklamakan Deserts in China and Mongolia.

Blast furnace

A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally iron.

 

In a blast furnace, fuel, ore, and flux (limestone) are continuously supplied through the top of the furnace, while air (sometimes with oxygen enrichment) is blown into the bottom of the chamber, so that the chemical reactions take place throughout the furnace as the material moves downward. The end products are usually molten metal and slag phases tapped from the bottom, and flue gases exiting from the top of the furnace. The downward flow of the ore and flux in contact with an upflow of hot, carbon monoxide-rich combustion gases is a countercurrent exchange process.

 

From Wikipedia, the free encyclopedia

Up with a fairly thick head and a furry tongue stuck to the roof of my mouth, it was the traditional cure-all of bacon butties that helped. That and the six coffees I sent down to keep the butties company.

 

For the morning we had cruised through the night to another sound/fjord, anchoring near to the wall of a glacier. All around were small mini-icebergs and other shards of ice, making this feel really like the high arctic for the first time.

 

All zodiacs were launched, so we could all partake in a cruise through the ice flows and along the edge of the glacier. Jools and I got in the first one, so we also got to experience the day with perfect reflections which made it very special indeed.

 

Most ice was white or clear, but recently calved ice was deep blue, and these offering the only contrast to the monocolours of snow, ice and rocks.

 

We powered to the edge of the area of thicker ice flows, then weaved our way through and along the front of the glacier, never getting within 500m of it. Sometimes all boats would cut their engines, passengers wouldn’t talk, so we could hear the sound of the arctic: the gentle bobbing of the ice caused by small calvings from the glacier, and the sound of cracking, with just about every piece of ice adding to the chorus. It wasn’t loud, jut there. Common Eider males called and Artic Skuas cruised looking for the first eggs of the season.

 

There had been no wind, so there were perfect reflections for the bergs and other lumps of ice in the icy sea. We weaved in and out, a line of ten boats, chugging along, all mesmerised by the sights of the bay and the seven mile long ice wall of the glacier.

 

At one point, it did calf, but only a small piece, and there was only a small wave. But ten minutes later, the swell from that reached us, causing the reflections to be stretched and compressed like a fairground hall of mirrors.

 

After two hours we made our way back the ship. We were all getting pretty cold by then, and needed coffee followed by lunch. After taking off our life vests and boots, we went up to the lounge for some welcome coffee and to warm up.

 

We cruised to our next anchorage, 14th July Bay, where there would be two activities: 1, a cruise along the cliffs looking for nesting birds, then a walk under the shadow of the huge cliffs, on which tens of thousands of birds nest, their guano fertilising the lower slopes, to make a “hanging garden”.

 

Today was the first time my back really ached, and so painful I almost skipped the trip out. But we have two days on board now, so I thought I would brave it out.

 

Back in the zodiacs, and out to the island, where the cliffs towered at something like a thousand feet, people already on the shore looked like ants in its shadow. Our boat cruised along the shore, where first of all we saw an Artic Fox, in its summer pelt, except for its tail, which was still white. High above a huge colony of Kittiwakes squawked and flew around, having seen the fox further down the cliffs.

 

Along further we saw more Kittiwake nests, though much closer, and a few Puffins looking out of crevices in the rock where they nest. Not nesting in burrows is, I think, unique to the Svalbard population.

 

After an hour we landed on the beach, I swapped lenses, and we began a slow amble along the beach looking for flora which might be in flower. Not much more than we saw before, but two Snow Buntings were gathering fur from a reindeer to line their nest.

 

At half five we got back in the boats and they brought us back to ship, not as clod as this morning, but my back was glad to being rested for a few days.

 

A quick coffee, and then the daily debrief before another three course meal and coffee.

 

After the red wine and whisky excess of the night before, we went to the cabin straight after dinner, and soon went to bed.

 

---------------------------------------------------

 

The Arctic fox (Vulpes lagopus), also known as the white fox, polar fox, or snow fox, is a small fox that belongs to the family of Canidae, native to the Arctic regions of the Northern Hemisphere and common throughout the Arctic tundra biome.[1][7][8][9] It is well adapted to living in cold environments, and is best known for its thick, warm fur that is also used as camouflage. It has a large and very fluffy tail. In the wild, most individuals do not live past their first year but some exceptional ones survive up to 11 years.[10] Its body length ranges from 46 to 68 cm (18 to 27 in), with a generally rounded body shape to minimize the escape of body heat.

 

The Arctic fox preys on many small creatures such as lemmings, voles, ringed seal pups, fish, waterfowl, and seabirds. It also eats carrion, berries, seaweed, and insects and other small invertebrates. Arctic foxes form monogamous pairs during the breeding season and they stay together to raise their young in complex underground dens. Occasionally, other family members may assist in raising their young. Natural predators of the Arctic fox are golden eagles,[11] Arctic wolves, polar bears,[12] wolverines, red foxes, and grizzly bears.

 

Arctic foxes must endure a temperature difference of up to 90–100 °C (160–180 °F) between the external environment and their internal core temperature.[15] To prevent heat loss, the Arctic fox curls up tightly tucking its legs and head under its body and behind its furry tail. This position gives the fox the smallest surface area to volume ratio and protects the least insulated areas. Arctic foxes also stay warm by getting out of the wind and residing in their dens.[16][15] Although the Arctic foxes are active year-round and do not hibernate, they attempt to preserve fat by reducing their locomotor activity.[16][17] They build up their fat reserves in the autumn, sometimes increasing their body weight by more than 50%. This provides greater insulation during the winter and a source of energy when food is scarce.

 

The Arctic fox contains advantageous genes to overcome extreme cold and starvation periods. Transcriptome sequencing has identified two genes that are under positive selection: Glycolipid transfer protein domain containing 1 (GLTPD1) and V-akt murine thymoma viral oncogene homolog 2 (AKT2). GLTPD1 is involved in the fatty acid metabolism, while AKT2 pertains to the glucose metabolism and insulin signaling.[31]

 

The average mass specific BMR and total BMR are 37% and 27% lower in the winter than the summer. The Arctic fox decreases its BMR via metabolic depression in the winter to conserve fat storage and minimize energy requirements. According to the most recent data, the lower critical temperature of the Arctic fox is at −7 °C (19 °F) in the winter and 5 °C (41 °F) in the summer. It was commonly believed that the Arctic fox had a lower critical temperature below −40 °C (−40 °F). However, some scientists have concluded that this statistic is not accurate since it was never tested using the proper equipment.[15]

 

About 22% of the total body surface area of the Arctic fox dissipates heat readily compared to red foxes at 33%. The regions that have the greatest heat loss are the nose, ears, legs, and feet, which is useful in the summer for thermal heat regulation. Also, the Arctic fox has a beneficial mechanism in their nose for evaporative cooling like dogs, which keeps the brain cool during the summer and exercise.[17] The thermal conductivity of Arctic fox fur in the summer and winter is the same; however, the thermal conductance of the Arctic fox in the winter is lower than the summer since fur thickness increases by 140%. In the summer, the thermal conductance of the Arctic foxes body is 114% higher than the winter, but their body core temperature is constant year-round.

 

One way that Arctic foxes regulate their body temperature is by utilizing a countercurrent heat exchange in the blood of their legs.[15] Arctic foxes can constantly keep their feet above the tissue freezing point (−1 °C (30 °F)) when standing on cold substrates without losing mobility or feeling pain. They do this by increasing vasodilation and blood flow to a capillary rete in the pad surface, which is in direct contact with the snow rather than the entire foot. They selectively vasoconstrict blood vessels in the center of the foot pad, which conserves energy and minimizes heat loss.[17][32] Arctic foxes maintain the temperature in their paws independently from the core temperature. If the core temperature drops, the pad of the foot will remain constantly above the tissue freezing point.

 

en.wikipedia.org/wiki/Arctic_fox

Clean Energy World (1.3 x 2.9 meters) is painted in acrylic on doubly primed canvas, It is based on a classical Fibonacci Sequence-based (Da Vinci Code) Golden Rectangle geometrical scaffolding. The painting is about the Clean Energy World of the New Jerusalem in "England's green and pleasant land" (William Blake and "Jerusalem"), this contrasting with the Zoroastrian duality obverse world of darkness and pollution. For details see 300.org: sites.google.com/site/300orgsite/300-org .

 

The world is acutely threatened by man-made climate change. Top climate scientists say that we must reduce the atmospheric carbon dioxide dioxide (CO2) concentration from the current 390 parts per million (ppm) to about 300 ppm for a safe planet for all people and all species (see "300.org - return atmosphere CO2 to 300 ppm": sites.google.com/site/300orgsite/300-org---return-atmosph... and "Climate Crisis Facts & Required Actions": sites.google.com/site/yarravalleyclimateactiongroup/clima... ).

 

To do this we need a rapid switch to the best non-carbon and renewable energy options (solar, wind, geothermal, wave, tide and hydro options) that are currently all cheaper than the true cost of coal burning-based power) and to energy efficiency, public transport, needs-based production, re-afforestation and return of carbon as biochar to soils coupled with correspondingly rapid cessation of fossil fuel burning, deforestation, methanogenic livestock production and population growth (see "Climate Crisis Facts & Required Actions": sites.google.com/site/yarravalleyclimateactiongroup/clima....

 

For a detailed discussion see "Gideon Polya, "Clean Energy World. “Clean Energy World” Painting. NASA’s Dr Hansen Pleads for NEGATIVE CO2 Emissions": sites.google.com/site/artforpeaceplanetmotherchild/clean-... , Climate Genocide: sites.google.com/site/climategenocide/ ; see also:

 

300.org: sites.google.com/site/300orgsite/ ;

 

Yarra Valley Climate Action Group: sites.google.com/site/yarravalleyclimateactiongroup/Home ;

 

Climate Crisis Articles: sites.google.com/site/climatecrisisarticles/ ;

 

Biofuel Genocide: sites.google.com/site/biofuelgenocide/ ;

 

Cut Carbon Emissions 80% by 2020: sites.google.com/site/cutcarbonemissions80by2020/ ;

 

100% renewable energy by 2020: sites.google.com/site/100renewableenergyby2020/ ;

 

Professor James Hansen (NASA, GISS, Columbia University), “It’s possible to avert the climate crisis”, Countercurrents, 29 November 2009: www.countercurrents.org/hansen291109.htm ;

 

Dr Andrew Glikson (paleoclimate & earth scientist, Senior Research Fellow, ANU; “Glikson Crater” named for him), “As sea level rises so does the level of climate change denial”, Countercurrents: www.countercurrents.org/glikson070210.htm .

  

.

 

Siena (Italy)

Effect film: Fuji Neopan PRO 1600

 

© Bruno Olivieri - brunoolivieri.effezero.it

Section longitudinale du rete mirabile chez l’anguille européenne. Des vaisseaux sanguins de toute taille (flèches - issus de l’artère vésicale ou se drainant dans la veine homologue) sont associés à la vessie gazeuse. Les plus petits vaisseaux à ce niveau sont les innombrables

capillaires (X) formant une structure complexe, le rete mirabile (« réseau ou faisceau admirable ») dans lequel les capillaires sanguins artériels et veineux sont disposés côte-à-côte, parallèles et à contre-courant, et sont en rapport étroit avec la glande à gaz.

 

- Pour plus de détails ou précisions, voir « Atlas of Fish Histology » CRC Press, ou « Histologie illustrée du poisson » (QUAE) ou s'adresser à Franck Genten (fgenten@gmail.com)

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Longitudinal section of the rete mirabile of an eel. The main blood vessel entering the anterior part of the gas bladder breaks up into smaller branches (arrows) which subdivide into a multitude of capillaries (X). The rete mirabile is a dense bundle of parallel arterial and venous capillaries arranged side by side (countercurrent system) and supplying the gas gland with blood.

 

- For more information or details, see « Atlas of Fish Histology » CRC Press, or « Histologie illustrée du poisson » (QUAE) or contact Franck Genten (fgenten@gmail.com)

 

Asamblea popular (20 de Mayo de 2011, Ciudad Real).

 

Todos los derechos reservados. No se permite su uso sin autorización previa.

 

Interesados en una copia a mayor resolución o sin firma ponerse en contacto por mensaje privado.

This is the main component of the hydronic system, where propane is burned to heat water for showers etc. as well as the glycol solution which circulates through radiators and the floor to provide cabin heat. It's a marvel of engineering. Note the nifty countercurrent heat exchanger combination air intake and exhaust - the exhaust heats the outside air coming in because the intake pipe is inside the exhaust pipe.

(I think this is the same article online).

 

The tank was an army group doing recruitment/info, in Bristol city centre, Saturday Oct 7th. This guy was protesting peacefully. I saw him exchange a few words with the Army guys, but nobody got cross or raised voices etc while I was there.

Faisceau de la zone périphérique du rein. L’une des particularités du rein des poissons cartilagineux est la très forte réabsorption d’urée à partir de l’urine primaire. Celle-ci implique l’existence d’un arrangement tubulaire en double épingle à cheveux au sein des faisceaux

latéraux et comprenant un canal (le collet) venant de la capsule de Bowman, deux autres canaux (segment intermédiaire et collecteur) issus de la «sinus zone» et deux portions tubulaires (P1 du tube proximal et partie initiale du tube distal) quittant le faisceau et se dirigeant vers

le parenchyme. Ce mécanisme à contre-courant forme deux boucles en « U » impliquant, pour la première, le collet et P1, et pour la seconde, le segment intermédiaire et le début du

tube distal. Un tube collecteur, quittant le faisceau et souvent empli de mucus, ainsi qu’un petit

vaisseau central (cercle) complètent souvent l’ensemble. Chaque faisceau est encerclé par une assise épaisse de conjonctif dit péritubulaire (collagène en turquoise) contenant des capillaires (carrés orange) et des noyaux allongés de fibrocytes. Voir aussi P10a_027.

  

- Pour plus de détails ou précisions, voir « Atlas of Fish Histology » CRC Press, ou « Histologie illustrée du poisson » (QUAE) ou s'adresser à Franck Genten (fgenten@gmail.com)

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Dogfish kidney bundle. The most amazing feature of the

elasmobranch kidney is that more than 90% of the urea is

resorbed from filtered primary urine : this involves a very

high urea concentration in plasma and body fluids and implies the existence of a specific mechanism enabling

reabsorption of urea by the kidney. Indeed, histological

studies have revealed that the renal tubules of sharks are highly elaborate. Each bundle consists of five canals which all belong to the same nephron. One canal (the neck segment NS) comes from the Bowman’s capsule, two canals (the intermediate segment IS and the collecting duct CT) come from the sinus zone and two last canals (the first part of proximal tubule P1 and the early distal tubule EDT) leave the bundle and run into the sinus zone. A large collecting duct leaves the bundle at its distal end. NS and P1, as well as IS and EDT form the two hairpin loops and the whole forms a double countercurrent mechanism allowing passive reabsorption of urea. A small bundle vessel (circle) is normally visible between the tubules. Each bundle is surrounded by an important peritubular connective sheath (collagen in turquoise) containing some capillaries (orange squares) and flattened connective tissue cells. See also P10a_027.

 

- For more information or details, see « Atlas of Fish Histology » CRC Press, or « Histologie illustrée du poisson » (QUAE) or contact Franck Genten (fgenten@gmail.com)

 

Got Gas?

 

$100/barrel by 2008?

Canuck says "Yes."

Professor says "No."

Market says "Wake Up!"

 

Dick Cheney's sadism!

 

Turkey Stink

 

Dollars? Are you joking?

 

(Created with fd's Flickr Toys.)

The arctic fox (Vulpes lagopus, formerly known as Alopex lagopus), also known as the white fox, polar fox or snow fox, is a small fox native to Arctic regions of the Northern Hemisphere and is common throughout the Arctic tundra biome. The Greek word alopex, (ἀλώπηξ) means a fox and Vulpes is the Latin version. Lagopus is derived from Ancient Greek lago (λαγως), meaning "hare", + pous (πους), "foot" and refers to the hair on its feet. Although it has previously been assigned to its own genus Alopex, genetic evidence places it in Vulpes (Mammal Species of the World) with the majority of the other foxes.

 

The arctic fox lives in some of the most frigid extremes on the planet. Among its adaptations for cold survival are its deep, thick fur, a system of countercurrent heat exchange in the circulation of paws to retain core temperature, and a good supply of body fat. The fox has a low surface area to volume ratio, as evidenced by its generally rounded body shape, short muzzle and legs, and short, thick ears. Since less of its surface area is exposed to the arctic cold, less heat escapes the body. Its furry paws allow it to walk on ice in search of food. The arctic fox has such keen hearing that it can precisely locate the position of prey under the snow. When it finds prey, it pounces and punches through the snow to catch its victim. Its fur changes colour with the seasons: in the winter it is white to blend in with snow, while in the summer it is brown.

 

The arctic fox will generally eat any small animal it can find: lemmings, voles, hares, owls, eggs, and carrion, etc. Lemmings are the most common prey. A family of foxes can eat dozens of lemmings each day. During April and May the arctic fox also preys on ringed seal pups when the young animals are confined to a snow den and are relatively helpless. Fish beneath the ice are also part of its diet. They also consume berries and seaweed and may thus be considered omnivores. It is a significant bird egg predator, excepting those of the largest tundra bird species. If there is an overabundance of food hunted, the arctic fox will bury what the family cannot eat. When its normal prey is scarce, the arctic fox scavenges the leftovers and even feces of larger predators, such as the polar bear, even though the bear's prey includes the arctic fox itself.

 

The arctic fox has a circumpolar range, meaning that it is found throughout the entire Arctic, including the outer edges of Greenland, Russia, Canada, Alaska, and Svalbard, as well as in Subarctic and alpine areas, such as Iceland and mainland alpine Scandinavia. The conservation status of the species is good, except for the Scandinavian mainland population. It is acutely endangered there, despite decades of legal protection from hunting and persecution. The total population estimate in all of Norway, Sweden and Finland is a mere 120 adult individuals.

 

The arctic fox is the only native land mammal to Iceland. It came to the isolated North Atlantic island at the end of the last ice age, walking over the frozen sea. The Arctic Fox Center in Súðavík contains an exhibition on the arctic fox and conducts studies on the influence of tourism on the population.

 

The abundance of the arctic fox species tends to fluctuate in a cycle along with the population of lemmings and voles (a 3-to-4-year cycle). Because the fox reproduces very quickly and often dies young, population levels are not seriously affected by trapping. The arctic fox has, nonetheless, been eradicated from many areas where humans are settled.

 

The pelts of arctic foxes with a slate blue coloration—an expression of a recessive gene—were especially valuable. They were transported to various previously fox-free Aleutian Islands during the 1920s. The program was successful in terms of increasing the population of blue foxes, but their predation of Aleutian Canadian geese conflicted with the goal of preserving that species.

 

The arctic fox is losing ground to the larger red fox. This has been attributed to climate change—the camouflage value of its lighter coat decreases with less snow cover. Red foxes dominate where their ranges begin to overlap by killing arctic foxes and their kits. An alternate explanation of the red fox's gains involves the gray wolf: Historically, it has kept red fox numbers down, but as the wolf has been hunted to near extinction in much of its former range, the red fox population has grown larger, and it has taken over the niche of top predator.[citation needed] In areas of northern Europe, there are programs in place that allow hunting of the red fox in the arctic fox's previous range.

 

As with many other game species, the best sources of historical and large scale population data are hunting bag records and questionnaires. There are several potential sources of error in such data collections. In addition, numbers vary widely between years due to the large population fluctuations. However, the total population of the arctic fox must be in the order of several hundred thousand animals.

 

The world population is thus not endangered, but two arctic fox subpopulations are. One is on Medny Island (Commander Islands, Russia), which was reduced by some 85-90%, to around 90 animals, as a result of mange caused by an ear tick introduced by dogs in the 1970s. The population is currently under treatment with antiparasitic drugs, but the result is still uncertain.

 

The other threatened population is the one in Fennoscandia (Norway, Sweden, Finland and Kola Peninsula). This population decreased drastically around the start of the 20th century as a result of extreme fur prices which caused severe hunting also during population lows. The population has remained at a low density for more than 90 years, with additional reductions during the last decade. The total population estimate for 1997 is around 60 adults in Sweden, 11 adults in Finland and 50 in Norway. From Kola, there are indications of a similar situation, suggesting a population of around 20 adults. The Fennoscandian population thus numbers a total of 140 breeding adults. Even after local lemming peaks, the arctic fox population tends to collapse back to levels dangerously close to non-viability.

 

The arctic fox is classed as a "prohibited new organism" under New Zealand's Hazardous Substances and New Organisms Act 1996 preventing it from being imported into the country

 

Maryland Zoo, Baltimore Md.

Hung. Over.

 

This guy is ridiculously alarmist and ill-informed, but there's something about these kinds of articles that I just can't get enough of these days...

 

www.countercurrents.org/goodchild230808.htm

 

Yesterday I met a rooster in Prospect Park.

 

Also, Alana found this quote by H.P. Lovecraft that I think is good:

 

"That is not dead which can eternal lie, and with strange æons even death may die."

(better on black, please press L)

Il fiume Krka sorge sotto la cascata del ruscello Krcic e scorre attraverso la pianura di Knin entrando in un kanyon lungo 50Km (profondo in alcuni punti anche 200m) formandovi una serie di cascate e di laghi. La cascata più grande è alta 26m e si trova nel corso superiore della Krka, mentre il lago più grande è quello di Visovac al centro del quale, su un'isola, sorge un monastero francescano. Controcorrente a questo isolotto si apre la cascata di Skradinski buk con i suoi 17 gradini, quindi la Krka confluisce nel lago Prikljansko formando un'ampia gola fino alla sua foce nel mare.

 

The river Krka rises under the fall of the brook Krcic and flows through the lowland of Knin entering a kanyon along 50Km (It also lavish in some points 200m) forming a series of falls and lakes. The greatest fall is tall 26m and is found in the superior progress of the Krka, while the greatest lake is that of Visovac to the center of which, on an island, a Franciscan monastery rises. Countercurrent in this islet opens the fall of Skradinski buk with its 17 steps, therefore the Krka meets in the lake Prikljansko forming an ample throat up to her mouth in the sea.

 

El río Krka surge bajo la catarata del arroyo Krcic y corre por el llano de Knin entrando en un kanyon largo 50Km, profundo en algunos también apuntas 200m, formándovos una serie de cataratas y lagos. La catarata más grande es alta 26m y se encuentra en el curso superior del Krka, mientras que el lago más grande es aquel de Visovac al centro del que, sobre una isla, surge un monasterio franciscano. Contracorriente a este islote se abre la catarata de Skradinski buk con los suyos 17 peldaños, por lo tanto el Krka confluye en el lago Prikljansko formando una amplia garganta hasta su desembocadura en el mar.

The Arctic fox (Alopex lagopus), also known as the polar fox, is a small fox native to cold Arctic regions of the Northern Hemisphere. The Arctic fox has smaller, more rounded ears, a more rounded braincase, and a slightly shorter and broader muzzle than the red fox. Its feet are furrier than those of other foxes.

 

The Arctic fox has evolved to live in the most frigid extremes on the planet. Among its adaptations for cold survival are its deep, thick fur, a system of countercurrent heat exchange in the circulation of paws to keep them from freezing, and a good supply of body fat. The fox has a low surface-area-to-volume ratio as evidenced by its generally rounded body shape, short muzzle and legs, and short, thick ears. Since less of its surface area is exposed to the cold, less heat escapes the body. Its furry paws allow it to walk on ice flows in search of food. It is also able to walk on top of snow and listen for the movements of prey underneath. It has the warmest fur of any mammal.

 

(from Wikipedia)

Il fiume Krka sorge sotto la cascata del ruscello Krcic e scorre attraverso la pianura di Knin entrando in un kanyon lungo 50Km (profondo in alcuni punti anche 200m) formandovi una serie di cascate e di laghi. La cascata più grande è alta 26m e si trova nel corso superiore della Krka, mentre il lago più grande è quello di Visovac al centro del quale, su un'isola, sorge un monastero francescano. Controcorrente a questo isolotto si apre la cascata di Skradinski buk con i suoi 17 gradini, quindi la Krka confluisce nel lago Prikljansko formando un'ampia gola fino alla sua foce nel mare.

 

The river Krka rises under the fall of the brook Krcic and flows through the lowland of Knin entering a kanyon along 50Km (It also lavish in some points 200m) forming a series of falls and lakes. The greatest fall is tall 26m and is found in the superior progress of the Krka, while the greatest lake is that of Visovac to the center of which, on an island, a Franciscan monastery rises. Countercurrent in this islet opens the fall of Skradinski buk with its 17 steps, therefore the Krka meets in the lake Prikljansko forming an ample throat up to her mouth in the sea.

 

El río Krka surge bajo la catarata del arroyo Krcic y corre por el llano de Knin entrando en un kanyon largo 50Km, profundo en algunos también apuntas 200m, formándovos una serie de cataratas y lagos. La catarata más grande es alta 26m y se encuentra en el curso superior del Krka, mientras que el lago más grande es aquel de Visovac al centro del que, sobre una isla, surge un monasterio franciscano. Contracorriente a este islote se abre la catarata de Skradinski buk con los suyos 17 peldaños, por lo tanto el Krka confluye en el lago Prikljansko formando una amplia garganta hasta su desembocadura en el mar.

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Davis Strait, Canada

 

Taken on August 30, 2018 (uploaded 1/9/19)

 

The strait was first explored by John DAVIS, leader of three voyages 1585-87 organized by merchants of London, England.

 

www.thecanadianencyclopedia.ca/en/article/davis-strait

 

Davis Strait, situated between BAFFIN ISLAND and Greenland, is the entrance to BAFFIN BAY from the North Atlantic. It is a large stretch of water over 950 km across at its greatest width and never less than 300 km wide. At the narrowest point, its submarine topography consists of an undersea ridge, a continuation of the mid-Labrador ridge, extending from the coast of Baffin Island to Greenland. The shallowest waters in the strait are found along this sill, from 350 to 550 m deep, before plunging down to abyssal basins on either side.

 

Some of the greatest depths in the eastern Arctic are reached here (3660 m) in the southern end of the strait. The surface waters are strongly affected by counterclockwise-flowing currents.

 

Along the west side, an outflow of cold water from the Arctic Basin moves south, at flow velocities of 8-20 km/day, to feed the Labrador current. On the east side the west Greenland countercurrent brings warmer water north. Ice conditions reflect this flow regime, with heavy ice movement and icebergs along the western shore, contrasting sharply with more open water along the Greenland side.

Lame branchiale, coupe sagittale au niveau du sinus veineux central. 1 : lame branchiale (parfois appelé filament ou lame primaire) – 2 : lamelles branchiales (lames secondaires) abritant l’abondant réseau capillaire – 3 :

globules rouges (noyau bien central) dans les capillaires lamellaires – 4 : globules rouges dans le sinus

veineux central de la lame.

Les cercles verts montrent une cellule en pilastre ou pilier (foncée) entourée par deux globules rouges. Ces cellules soutiennent et maintiennent séparées les fines parois épithéliales de la lamelle. Le sang au niveau des lamelles circule parallèlement, mais en sens opposé, à celui de l’eau. Ce mécanisme à contre-courant, dont le principe est très efficace, peut se retrouver dans divers groupes et organes, et permet, dans le cas présent, d’extraire jusqu’à 80 % de l’O2 dissous dans l’eau !

 

- Pour plus de détails ou précisions, voir « Atlas of Fish Histology » CRC Press, ou « Histologie illustrée du poisson » (QUAE) ou s'adresser à Franck Genten (fgenten@gmail.com)

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Gill filament, sagittal section through venous sinus.

1 : gill filament or primary lamella – 2 : secondary

lamellae with central capillary network – 3 : red blood cells

within capillary lumen of secondary lamellae – 4 : red blood cells (oxygenated blood) in the central venous sinus of the primary lamella.

The green circles surround one pillar cell with two red blood cells side-by-side. The direction of blood flow from afferent to efferent arterioles is opposite to the direction of water flow over the lamellae (countercurrent exchange). This arrangement allows very efficient oxygen exchange (up to 80 % !!).

 

- For more information or details, see « Atlas of Fish Histology » CRC Press, or « Histologie illustrée du poisson » (QUAE) or contact Franck Genten (fgenten@gmail.com)

 

The lymphatic system plays two key roles in the drainage of waste-containing cerebrospinal fluid from around the brain: glymphatic mechanisms (the perivascular countercurrent movement of fluid along the surface of veins and venules rather than within additional lymphatic vessels) and drainage directly into dural lymphatic vessels. (Image credit: “Glymphatics and Dural Lymphatic Vessels" by Julie Jenks is a derivative of the original work by Daniel Donnelly and is licensed under CC BY 4.0)

A camel is an even-toed ungulate within the genus Camelus, bearing distinctive fatty deposits known as "humps" on its back. The two surviving species of camel are the dromedary, or one-humped camel (C. dromedarius), which inhabits the Middle East and the Horn of Africa; and the bactrian, or two-humped camel (C. bactrianus), which inhabits Central Asia. Both species have been domesticated; they provide milk, meat, hair for textiles or goods such as felted pouches, and are working animals with tasks ranging from human transport to bearing loads.

 

The term "camel" is derived via Latin and Greek (camelus and κάμηλος kamēlos respectively) from Hebrew or Phoenician gāmāl.

 

"Camel" is also used more broadly to describe any of the six camel-like mammals in the family Camelidae: the two true camels and the four New World camelids: the llama, alpaca, guanaco, and vicuña of South America.

 

BIOLOGY

The average life expectancy of a camel is 40 to 50 years. A full-grown adult camel stands 1.85 m at the shoulder and 2.15 m at the hump. Camels can run at up to 65 km/h in short bursts and sustain speeds of up to 40 km/h. Bactrian camels weigh 300 to 1,000 kg and dromedaries 300 to 600 kg.

 

The male dromedary camel has in its throat an organ called a dulla, a large, inflatable sac he extrudes from his mouth when in rut to assert dominance and attract females. It resembles a long, swollen, pink tongue hanging out of the side of its mouth. Camels mate by having both male and female sitting on the ground, with the male mounting from behind. The male usually ejaculates three or four times within a single mating session. Camelids are the only ungulates to mate in a sitting position.

 

ECOLOGICAL AND BEHAVIORAL ADAPTIONS

Camels do not directly store water in their humps as was once commonly believed. The humps are actually reservoirs of fatty tissue: concentrating body fat in their humps minimizes the insulating effect fat would have if distributed over the rest of their bodies, helping camels survive in hot climates. When this tissue is metabolized, it yields more than one gram of water for every gram of fat processed. This fat metabolization, while releasing energy, causes water to evaporate from the lungs during respiration (as oxygen is required for the metabolic process): overall, there is a net decrease in water.

 

Camels have a series of physiological adaptations that allow them to withstand long periods of time without any external source of water. Unlike other mammals, their red blood cells are oval rather than circular in shape. This facilitates the flow of red blood cells during dehydration and makes them better at withstanding high osmotic variation without rupturing when drinking large amounts of water: a 600 kg camel can drink 200 L of water in three minutes.

 

Camels are able to withstand changes in body temperature and water consumption that would kill most other animals. Their temperature ranges from 34 °C at dawn and steadily increases to 40 °C by sunset, before they cool off at night again. Maintaining the brain temperature within certain limits is critical for animals; to assist this, camels have a rete mirabile, a complex of arteries and veins lying very close to each other which utilizes countercurrent blood flow to cool blood flowing to the brain. Camels rarely sweat, even when ambient temperatures reach 49 °C Any sweat that does occur evaporates at the skin level rather than at the surface of their coat; the heat of vaporization therefore comes from body heat rather than ambient heat. Camels can withstand losing 25% of their body weight to sweating, whereas most other mammals can withstand only about 12–14% dehydration before cardiac failure results from circulatory disturbance.

 

When the camel exhales, water vapor becomes trapped in their nostrils and is reabsorbed into the body as a means to conserve water. Camels eating green herbage can ingest sufficient moisture in milder conditions to maintain their bodies' hydrated state without the need for drinking.

 

The camels' thick coats insulate them from the intense heat radiated from desert sand; a shorn camel must sweat 50% more to avoid overheating. During the summer the coat becomes lighter in color, reflecting light as well as helping avoid sunburn. The camel's long legs help by keeping its body farther from the ground, which can heat up to 70 °C. Dromedaries have a pad of thick tissue over the sternum called the pedestal. When the animal lies down in a sternal recumbent position, the pedestal raises the body from the hot surface and allows cooling air to pass under the body.

 

Camels' mouths have a thick leathery lining, allowing them to chew thorny desert plants. Long eyelashes and ear hairs, together with nostrils that can close, form a barrier against sand. If sand gets lodged in their eyes, they can dislodge it using their transparent third eyelid. The camels' gait and widened feet help them move without sinking into the sand.

 

The kidneys and intestines of a camel are very efficient at reabsorbing water. Camel urine comes out as a thick syrup, and camel feces are so dry that they do not require drying when the Bedouins use them to fuel fires.

 

Camels' immune system differs from those of other mammals. Normally, the Y-shaped antibody molecules consist of two heavy (or long) chains along the length of the Y, and two light (or short) chains at each tip of the Y. Camels, in addition to these, also have antibodies made of only two heavy chains, a trait that makes them smaller and more durable. These "heavy-chain-only" antibodies, discovered in 1993, are thought to have developed 50 million years ago, after camelids split from ruminants and pigs.

 

GENETICS

The karyotypes of different camelid species have been studied earlier by many groups, but no agreement on chromosome nomenclature of camelids has been reached. A 2007 study flow sorted camel chromosomes, building on the fact that camels have 37 pairs of chromosomes (2n=74), and found that the karyotime consisted of one metacentric, three submetacentric, and 32 acrocentric autosomes. The Y is a small metacentric chromosome, while the X is a large metacentric chromosome.The hybrid camel, a hybrid between Bactrian and dromedary camels, has one hump, though it has an indentation 4–12 cm deep that divides the front from the back. The hybrid is 2.15 m at the shoulder and 2.32 m tall at the hump. It weighs an average of 650 kg and can carry around 400 to 450 kg, which is more than either the dromedary or Bactrian can. According to molecular data, the New World and Old World camelids diverged 11 million years ago. In spite of this, these species can still hybridize and produce fertile offspring. The cama is a camel–llama hybrid bred by scientists who wanted to see how closely related the parent species were. Scientists collected semen from a camel via an artificial vagina and inseminated a llama after stimulating ovulation with gonadotrophin injections. The cama has ears halfway between the length of camel and llama ears, no hump, longer legs than the llama, and partially cloven hooves. According to cama breeder Lulu Skidmore, cama have "the fleece of the llamas" and "the strength and patience of the camel". Like the mule, camas are sterile, despite both parents having the same number of chromosomes.

 

EVOLUTION

The earliest known camel, called Protylopus, lived in North America 40 to 50 million years ago (during the Eocene). It was about the size of a rabbit and lived in the open woodlands of what is now South Dakota. By 35 million years ago, the Poebrotherium was the size of a goat and had many more traits similar to camels and llamas. The hoofed Stenomylus, which walked on the tips of its toes, also existed around this time, and the long-necked Aepycamelus evolved in the Miocene.

 

The direct ancestor of all modern camels, Procamelus, existed in the upper Miocone and lower Pliocene. Around 3–5 million years ago, the North American Camelidae spread to South America via the Isthmus of Panama, where they gave rise to guanacos and related animals, and to Asia via the Bering land bridge. Surprising finds of fossil Paracamelus on Ellesmere Island beginning in 2006 in the high Canadian Arctic indicate the dromedary is descended from a larger, boreal browser whose hump may have evolved as an adaptation in a cold climate. This creature is estimated to have stood around nine feet tall.

 

The last camel native to North America was Camelops hesternus, which vanished along with horses, short-faced bears, mammoths and mastodons, ground sloths, sabertooth cats, and many other megafauna, coinciding with the migration of humans from Asia.

 

DOMESTICATION

Most camels surviving today are domesticated. Along with many other megafauna in North America, the original wild camels were wiped out during the spread of Native Americans from Asia into North America, 12,000 to 10,000 years ago. The only wild camels left are the Bactrian camels of the Gobi Desert.

 

Like the horse, before their extinction in their native land, camels spread across the Bering land bridge, moving the opposite direction from the Asian immigration to America, to survive in the Old World and eventually be domesticated and spread globally by humans.

 

Dromedaries may have first been domesticated by humans in Somalia and southern Arabia, around 3,000 BC, the Bactrian in central Asia around 2,500 BC, as at Shar-i Sokhta (also known as the Burnt City), Iran.

 

Discussions concerning camel domestication in Mesopotamia are often related to mentions of camels in the Hebrew Bible. The International Standard Bible Encyclopedia: E-J for instance mentions that "In accord with patriarchal traditions, cylinder seals from Middle Bronze Age Mesopotamia showed riders seated upon camels."

 

Martin Heide's 2010 work on the domestication of the camel tentatively concludes that the bactrian camel was domesticated by at least the middle of the third millennium somewhere east of the Zagros Mountains, then moving into Mesopotamia, and suggests that mentions of camels "in the patriarchal narratives may refer, at least in some places, to the Bactrian camel." while noting that the camel is not mentioned in relationship to Canaan.

 

Recent excavations in the Timna Valley by Lidar Sapir-Hen and Erez Ben-Yosef discovered what may be the earliest domestic camel bones found in Israel or even outside the Arabian peninsula, dating to around 930 BCE. This garnered considerable media coverage as it was described as evidence that the stories of Abraham, Joseph, Jacob and Esau were written after this time.

 

The existence of camels in Mesopotamia but not in Israel is not a new idea. According to an article in Time Magazine, the historian Richard Bulliet wrote in his 1975 book "The Camel and the Wheel" that "the occasional mention of camels in patriarchal narratives does not mean that the domestic camels were common in the Holy Land at that period." The archaeologist William F. Albright writing even earlier saw camels in the Bible as an anachronism. The official report by Sapir-Hen and Ben-Joseph notes that "The introduction of the dromedary camel (Camelus dromedarius) as a pack animal to the southern Levant signifies a crucial juncture in the history of the region; it substantially facilitated trade across the vast deserts of Arabia, promoting both economic and social change (e.g., Kohler 1984; Borowski 1998: 112-116; Jasmin 2005). This, together with the depiction of camels in the Patriarchal narrative, has generated extensive discussion regarding the date of the earliest domestic camel in the southern Levant (and beyond) (e.g., Albright 1949: 207; Epstein 1971: 558-584; Bulliet 1975; Zarins 1989; Köhler-Rollefson 1993; Uerpmann and Uerpmann 2002; Jasmin 2005; 2006; Heide 2010; Rosen and Saidel 2010; Grigson 2012). Most scholars today agree that the dromedary was exploited as a pack animal sometime in the early Iron Age (not before the 12th century BCE)" and concludes that "Current data from copper smelting sites of the Aravah Valley enable us to pinpoint the introduction of domestic camels to the southern Levant more precisely based on stratigraphic contexts associated with an extensive suite of radiocarbon dates. The data indicate that this event occurred not earlier than the last third of the 10th century BCE and most probably during this time. The coincidence of this event with a major reorganization of the copper industry of the region - attributed to the results of the campaign of Pharaoh Shoshenq I - raises the possibility that the two were connected, and that camels were introduced as part of the efforts to improve efficiency by facilitating trade."

 

MILITARY USES

By at least 1200 BC, the first camel saddles had appeared, and Bactrian camels could be ridden. The first saddle was positioned to the back of the camel, and control of the Bactrian camel was exercised by means of a stick. However, between 500–100 BC, Bactrian camels attained military use. New saddles, which were inflexible and bent, were put over the humps and divided the rider's weight over the animal. In the seventh century BC, the military Arabian saddle appeared, which improved the saddle design again slightly.

 

Camel cavalries have been used in wars throughout Africa, the Middle East, and into modern-day Border Security Force of India (though as of July 2012, the BSF has planned the replacement of camels with ATVs). The first use of camel cavalries was in the Battle of Qarqar in 853 BC. Armies have also used camels as freight animals instead of horses and mules.

In the East Roman Empire, the Romans used auxiliary forces known as dromedarii, whom they recruited in desert provinces. The camels were used mostly in combat because of their ability to scare off horses at close ranges (horses are afraid of the camels' scent), a quality famously employed by the Achaemenid Persians when fighting Lydia in the Battle of Thymbra.

 

19th and 20th CENTURIES

The United States Army established the U.S. Camel Corps, which was stationed in California in the late 19th century. One may still see stables at the Benicia Arsenal in Benicia, California, where they nowadays serve as the Benicia Historical Museum. Though the experimental use of camels was seen as a success (John B. Floyd, Secretary of War in 1858, recommended that funds be allocated towards obtaining a thousand more camels), the outbreak of the American Civil War saw the end of the Camel Corps: Texas became part of the Confederacy, and most of the camels were left to wander away into the desert.

 

France created a méhariste camel corps in 1912 as part of the Armée d'Afrique in the Sahara in order to exercise greater control over the camel-riding Tuareg and Arab insurgents, as previous efforts to defeat them on foot had failed. The camel-mounted units remained in service until the end of French rule over Algeria in 1962.

 

In 1916, the British created the Imperial Camel Corps. It was originally used to fight the Senussi, but was later used in the Sinai and Palestine Campaign in World War I. The Imperial Camel Corps comprised infantrymen mounted on camels for movement across desert, though they dismounted at battle sites and fought on foot. After July 1918, the Corps began to become run down, receiving no new reinforcements, and was formally disbanded in 1919.

 

In World War I, the British Army also created the Egyptian Camel Transport Corps, which consisted of a group of Egyptian camel drivers and their camels. The Corps supported British war operations in Sinai, Palestine, and Syria by transporting supplies to the troops.

 

The Somaliland Camel Corps was created by colonial authorities in British Somaliland in 1912; it was disbanded in 1944.

 

Bactrian camels were used by Romanian forces during World War II in the Caucasian region.

 

The Bikaner Camel Corps of British India fought alongside the British Indian Army in World Wars I and II.

 

The Tropas Nómadas (Nomad Troops) were an auxiliary regiment of Sahrawi tribesmen serving in the colonial army in Spanish Sahara (today Western Sahara). Operational from the 1930s until the end of the Spanish presence in the territory in 1975, the Tropas Nómadas were equipped with small arms and led by Spanish officers. The unit guarded outposts and sometimes conducted patrols on camelback.

 

FOOD USES

DAIRY

Camel milk is a staple food of desert nomad tribes and is sometimes considered a meal in and of itself; a nomad can live on only camel milk for almost a month. Camel milk is rich in vitamins, minerals, proteins, and immunoglobulins; compared to cow's milk, it is lower in fat and lactose, and higher in potassium, iron, and vitamin C. Bedouins believe the curative powers of camel milk are enhanced if the camel's diet consists of certain desert plants. Camel milk can readily be made into a drinkable yogurt, as well as butter or cheese, though the yields for cheese tend to be low.

 

Camel milk cannot be made into butter by the traditional churning method. It can be made if it is soured first, churned, and a clarifying agent is then added. Until recently, camel milk could not be made into camel cheese because rennet was unable to coagulate the milk proteins to allow the collection of curds. Developing less wasteful uses of the milk, the FAO commissioned Professor J.P. Ramet of the École Nationale Supérieure d'Agronomie et des Industries Alimentaires, who was able to produce curdling by the addition of calcium phosphate and vegetable rennet. The cheese produced from this process has low levels of cholesterol and is easy to digest, even for the lactose intolerant. The sale of camel cheese is limited owing to the small output of the few dairies producing camel cheese and the absence of camel cheese in local (West African) markets. Cheese imports from countries that traditionally breed camels are difficult to obtain due to restrictions on dairy imports from these regions.

 

Additionally, camel milk has been made into ice cream in a Netherlands camel farm.

 

MEAT

A camel carcass can provide a substantial amount of meat. The male dromedary carcass can weigh 300–400 kg, while the carcass of a male Bactrian can weigh up to 650 kg. The carcass of a female dromedary weighs less than the male, ranging between 250 and 350 kg. The brisket, ribs and loin are among the preferred parts, and the hump is considered a delicacy. The hump contains "white and sickly fat", which can be used to make the khli (preserved meat) of mutton, beef, or camel. Camel meat is reported to taste like coarse beef, but older camels can prove to be very tough, although camel meat becomes more tender the more it is cooked. The Abu Dhabi Officers' Club serves a camel burger mixed with beef or lamb fat in order to improve the texture and taste. In Karachi, Pakistan, some restaurants prepare nihari from camel meat. In Syria and Egypt, there are specialist camel butchers.

 

Camel meat has been eaten for centuries. It has been recorded by ancient Greek writers as an available dish at banquets in ancient Persia, usually roasted whole. The ancient Roman emperor Heliogabalus enjoyed camel's heel.[31] Camel meat is still eaten in certain regions, including Eritrea, Somalia, Djibouti, Saudi Arabia, Egypt, Syria, Libya, Sudan, Ethiopia, Kazakhstan, and other arid regions where alternative forms of protein may be limited or where camel meat has had a long cultural history. Camel blood is also consumable, as is the case among pastoralists in northern Kenya, where camel blood is drunk with milk and acts as a key source of iron, vitamin D, salts and minerals. Camel meat is also occasionally found in Australian cuisine: for example, a camel lasagna is available in Alice Springs.

 

A 2005 report issued jointly by the Saudi Ministry of Health and the United States Centers for Disease Control and Prevention details cases of human bubonic plague resulting from the ingestion of raw camel liver.

 

RELIGION

ISLAM

Camel meat is halal for Muslims. However, according to some Islamic schools of thought, a state of impurity is brought on by the consumption of it. Consequently, these schools hold that Muslims must perform wudhu (ablution) before the next time they pray after eating camel meat.

 

Also, some Islamic schools of thought consider it haraam for a Muslim to perform salat in places where camels lie, as it is said to be a dwelling place of shaytan.

 

According to Suni ahadith collected by Bukhari and Muslim, Muhammad ordered a certain group of people to drink camel milk and urine as a medicine. However, according to Abū Ḥanīfa, the drinking of camel urine, while not forbidden (ḥaram), is disliked (makrūh) in Islam.

 

Camel urine is sold as traditional medicine in shops in Saudi Arabia. The Sunni scholar Muhammad Al-Munajjid's IslamQA.info recommends camel urine as beneficial to curing certain diseases and to human health and cited Ahadith and scientific studies as justification. King Abdulaziz University researcher Dr. Faten Abdel-Rajman Khorshid has claimed that cancer and other diseases could be treated with camel urine as recommended by the Prophet. The United Arab Emirates "Arab Science and Technology Foundation" reported that cancer could be treated with camel urine. Camel urine was also prescribed as a treatment by Zaghloul El-Naggar, a religious scholar. Camel urine is the only urine which is permitted to be drunk according to the Hanbali madhhab of Sunni Islam. The World Health Organization said that camel urine consumption may be a factor in the spread of the MERS virus in Saudi Arabia. The Gulf Times writer Ahmad al-Sayyed wrote that various afflictions are dealt with camel urine by people. Dandruff, scalp ailments, hair, sores, and wounds were recommended to be treated with camel urine by Ibn Sina. Arab American University Professor of Cell Biology and Immunology Bashar Saad (PhD) along with Omar Said (PhD) wrote that medicinal use of camel urine is approved of and promoted by Islam since it was recommended by the prophet. A test on mice found that cytotoxic effects similar to cyclophosphamide were induced on bone marrow by camel urine. Besides for consumption as a medicinal drink, camel urine is believed to help treat hair. Bites from insects were warded off with camel urine, which also served as a shampoo. Camel urine is also used to help treat asthma, infections, treat hair, sores, hair growth and boost libido.

 

Several Sunni Ahadith mention drinking camel urine. Some Shia criticized Wahhabis for camel urine treatment. Shia scholars also recommend the medicinal use of camel urine. Shia Hadith on Imam Ja'far al-Sadiq reported that shortness of breath (asthma) was treated with camel urine. Shia Marja Ayatollah Sistani said that for medicinal purposes only, sheep, cow, and camel urine can be drunk.

 

JUDAISM

According to Jewish tradition, camel meat and milk are not kosher. Camels possess only one of the two kosher criteria; although they chew their cud, they do not possess cloven hooves:

 

Nevertheless these shall ye not eat of them that only chew the cud, or of them that only part the hoof: the camel, because he cheweth the cud but parteth not the hoof, he is unclean unto you.

— Leviticus 11:4

 

DISTRIBUTION ANDNUMBERS

There are around 14 million camels alive as of 2010, with 90% being dromedaries. Dromedaries alive today are domesticated animals (mostly living in the Horn of Africa, the Sahel, Maghreb, Middle East and South Asia). The Horn region alone has the largest concentration of camels in the world, where the dromedaries constitute an important part of local nomadic life. They provide nomadic people in Somalia (which has the largest camel herd in the world) and Ethiopia with milk, food, and transportation.

 

The Bactrian camel is, as of 2010, reduced to an estimated 1.4 million animals, most of which are domesticated. The only truly wild Bactrian camels, of which there are less than one thousand, are thought to inhabit the Gobi Desert in China and Mongolia.

 

The largest population of feral camels is in Australia. There are around 700,000 feral dromedary camels in central parts of Australia, descended from those introduced as a method of transport in the 19th and early 20th centuries. This population is growing about 8% per year. Representatives of the Australian government have culled more than 100,000 of the animals in part because the camels use too much of the limited resources needed by sheep farmers.

 

A small population of introduced camels, dromedaries and Bactrians, wandered through Southwest United States after having been imported in the 1800s as part of the U.S. Camel Corps experiment. When the project ended, they were used as draft animals in mines and escaped or were released. Twenty-five U.S. camels were bought and imported to Canada during the Cariboo Gold Rush.

 

WIKIPEDIA

A camel is an even-toed ungulate within the genus Camelus, bearing distinctive fatty deposits known as "humps" on its back. The two surviving species of camel are the dromedary, or one-humped camel (C. dromedarius), which inhabits the Middle East and the Horn of Africa; and the bactrian, or two-humped camel (C. bactrianus), which inhabits Central Asia. Both species have been domesticated; they provide milk, meat, hair for textiles or goods such as felted pouches, and are working animals with tasks ranging from human transport to bearing loads.

 

The term "camel" is derived via Latin and Greek (camelus and κάμηλος kamēlos respectively) from Hebrew or Phoenician gāmāl.

 

"Camel" is also used more broadly to describe any of the six camel-like mammals in the family Camelidae: the two true camels and the four New World camelids: the llama, alpaca, guanaco, and vicuña of South America.

 

BIOLOGY

The average life expectancy of a camel is 40 to 50 years. A full-grown adult camel stands 1.85 m at the shoulder and 2.15 m at the hump. Camels can run at up to 65 km/h in short bursts and sustain speeds of up to 40 km/h. Bactrian camels weigh 300 to 1,000 kg and dromedaries 300 to 600 kg.

 

The male dromedary camel has in its throat an organ called a dulla, a large, inflatable sac he extrudes from his mouth when in rut to assert dominance and attract females. It resembles a long, swollen, pink tongue hanging out of the side of its mouth. Camels mate by having both male and female sitting on the ground, with the male mounting from behind. The male usually ejaculates three or four times within a single mating session. Camelids are the only ungulates to mate in a sitting position.

 

ECOLOGICAL AND BEHAVIORAL ADAPTIONS

Camels do not directly store water in their humps as was once commonly believed. The humps are actually reservoirs of fatty tissue: concentrating body fat in their humps minimizes the insulating effect fat would have if distributed over the rest of their bodies, helping camels survive in hot climates. When this tissue is metabolized, it yields more than one gram of water for every gram of fat processed. This fat metabolization, while releasing energy, causes water to evaporate from the lungs during respiration (as oxygen is required for the metabolic process): overall, there is a net decrease in water.

 

Camels have a series of physiological adaptations that allow them to withstand long periods of time without any external source of water. Unlike other mammals, their red blood cells are oval rather than circular in shape. This facilitates the flow of red blood cells during dehydration and makes them better at withstanding high osmotic variation without rupturing when drinking large amounts of water: a 600 kg camel can drink 200 L of water in three minutes.

 

Camels are able to withstand changes in body temperature and water consumption that would kill most other animals. Their temperature ranges from 34 °C at dawn and steadily increases to 40 °C by sunset, before they cool off at night again. Maintaining the brain temperature within certain limits is critical for animals; to assist this, camels have a rete mirabile, a complex of arteries and veins lying very close to each other which utilizes countercurrent blood flow to cool blood flowing to the brain. Camels rarely sweat, even when ambient temperatures reach 49 °C Any sweat that does occur evaporates at the skin level rather than at the surface of their coat; the heat of vaporization therefore comes from body heat rather than ambient heat. Camels can withstand losing 25% of their body weight to sweating, whereas most other mammals can withstand only about 12–14% dehydration before cardiac failure results from circulatory disturbance.

 

When the camel exhales, water vapor becomes trapped in their nostrils and is reabsorbed into the body as a means to conserve water. Camels eating green herbage can ingest sufficient moisture in milder conditions to maintain their bodies' hydrated state without the need for drinking.

 

The camels' thick coats insulate them from the intense heat radiated from desert sand; a shorn camel must sweat 50% more to avoid overheating. During the summer the coat becomes lighter in color, reflecting light as well as helping avoid sunburn. The camel's long legs help by keeping its body farther from the ground, which can heat up to 70 °C. Dromedaries have a pad of thick tissue over the sternum called the pedestal. When the animal lies down in a sternal recumbent position, the pedestal raises the body from the hot surface and allows cooling air to pass under the body.

 

Camels' mouths have a thick leathery lining, allowing them to chew thorny desert plants. Long eyelashes and ear hairs, together with nostrils that can close, form a barrier against sand. If sand gets lodged in their eyes, they can dislodge it using their transparent third eyelid. The camels' gait and widened feet help them move without sinking into the sand.

 

The kidneys and intestines of a camel are very efficient at reabsorbing water. Camel urine comes out as a thick syrup, and camel feces are so dry that they do not require drying when the Bedouins use them to fuel fires.

 

Camels' immune system differs from those of other mammals. Normally, the Y-shaped antibody molecules consist of two heavy (or long) chains along the length of the Y, and two light (or short) chains at each tip of the Y. Camels, in addition to these, also have antibodies made of only two heavy chains, a trait that makes them smaller and more durable. These "heavy-chain-only" antibodies, discovered in 1993, are thought to have developed 50 million years ago, after camelids split from ruminants and pigs.

 

GENETICS

The karyotypes of different camelid species have been studied earlier by many groups, but no agreement on chromosome nomenclature of camelids has been reached. A 2007 study flow sorted camel chromosomes, building on the fact that camels have 37 pairs of chromosomes (2n=74), and found that the karyotime consisted of one metacentric, three submetacentric, and 32 acrocentric autosomes. The Y is a small metacentric chromosome, while the X is a large metacentric chromosome.The hybrid camel, a hybrid between Bactrian and dromedary camels, has one hump, though it has an indentation 4–12 cm deep that divides the front from the back. The hybrid is 2.15 m at the shoulder and 2.32 m tall at the hump. It weighs an average of 650 kg and can carry around 400 to 450 kg, which is more than either the dromedary or Bactrian can. According to molecular data, the New World and Old World camelids diverged 11 million years ago. In spite of this, these species can still hybridize and produce fertile offspring. The cama is a camel–llama hybrid bred by scientists who wanted to see how closely related the parent species were. Scientists collected semen from a camel via an artificial vagina and inseminated a llama after stimulating ovulation with gonadotrophin injections. The cama has ears halfway between the length of camel and llama ears, no hump, longer legs than the llama, and partially cloven hooves. According to cama breeder Lulu Skidmore, cama have "the fleece of the llamas" and "the strength and patience of the camel". Like the mule, camas are sterile, despite both parents having the same number of chromosomes.

 

EVOLUTION

The earliest known camel, called Protylopus, lived in North America 40 to 50 million years ago (during the Eocene). It was about the size of a rabbit and lived in the open woodlands of what is now South Dakota. By 35 million years ago, the Poebrotherium was the size of a goat and had many more traits similar to camels and llamas. The hoofed Stenomylus, which walked on the tips of its toes, also existed around this time, and the long-necked Aepycamelus evolved in the Miocene.

 

The direct ancestor of all modern camels, Procamelus, existed in the upper Miocone and lower Pliocene. Around 3–5 million years ago, the North American Camelidae spread to South America via the Isthmus of Panama, where they gave rise to guanacos and related animals, and to Asia via the Bering land bridge. Surprising finds of fossil Paracamelus on Ellesmere Island beginning in 2006 in the high Canadian Arctic indicate the dromedary is descended from a larger, boreal browser whose hump may have evolved as an adaptation in a cold climate. This creature is estimated to have stood around nine feet tall.

 

The last camel native to North America was Camelops hesternus, which vanished along with horses, short-faced bears, mammoths and mastodons, ground sloths, sabertooth cats, and many other megafauna, coinciding with the migration of humans from Asia.

 

DOMESTICATION

Most camels surviving today are domesticated. Along with many other megafauna in North America, the original wild camels were wiped out during the spread of Native Americans from Asia into North America, 12,000 to 10,000 years ago. The only wild camels left are the Bactrian camels of the Gobi Desert.

 

Like the horse, before their extinction in their native land, camels spread across the Bering land bridge, moving the opposite direction from the Asian immigration to America, to survive in the Old World and eventually be domesticated and spread globally by humans.

 

Dromedaries may have first been domesticated by humans in Somalia and southern Arabia, around 3,000 BC, the Bactrian in central Asia around 2,500 BC, as at Shar-i Sokhta (also known as the Burnt City), Iran.

 

Discussions concerning camel domestication in Mesopotamia are often related to mentions of camels in the Hebrew Bible. The International Standard Bible Encyclopedia: E-J for instance mentions that "In accord with patriarchal traditions, cylinder seals from Middle Bronze Age Mesopotamia showed riders seated upon camels."

 

Martin Heide's 2010 work on the domestication of the camel tentatively concludes that the bactrian camel was domesticated by at least the middle of the third millennium somewhere east of the Zagros Mountains, then moving into Mesopotamia, and suggests that mentions of camels "in the patriarchal narratives may refer, at least in some places, to the Bactrian camel." while noting that the camel is not mentioned in relationship to Canaan.

 

Recent excavations in the Timna Valley by Lidar Sapir-Hen and Erez Ben-Yosef discovered what may be the earliest domestic camel bones found in Israel or even outside the Arabian peninsula, dating to around 930 BCE. This garnered considerable media coverage as it was described as evidence that the stories of Abraham, Joseph, Jacob and Esau were written after this time.

 

The existence of camels in Mesopotamia but not in Israel is not a new idea. According to an article in Time Magazine, the historian Richard Bulliet wrote in his 1975 book "The Camel and the Wheel" that "the occasional mention of camels in patriarchal narratives does not mean that the domestic camels were common in the Holy Land at that period." The archaeologist William F. Albright writing even earlier saw camels in the Bible as an anachronism. The official report by Sapir-Hen and Ben-Joseph notes that "The introduction of the dromedary camel (Camelus dromedarius) as a pack animal to the southern Levant signifies a crucial juncture in the history of the region; it substantially facilitated trade across the vast deserts of Arabia, promoting both economic and social change (e.g., Kohler 1984; Borowski 1998: 112-116; Jasmin 2005). This, together with the depiction of camels in the Patriarchal narrative, has generated extensive discussion regarding the date of the earliest domestic camel in the southern Levant (and beyond) (e.g., Albright 1949: 207; Epstein 1971: 558-584; Bulliet 1975; Zarins 1989; Köhler-Rollefson 1993; Uerpmann and Uerpmann 2002; Jasmin 2005; 2006; Heide 2010; Rosen and Saidel 2010; Grigson 2012). Most scholars today agree that the dromedary was exploited as a pack animal sometime in the early Iron Age (not before the 12th century BCE)" and concludes that "Current data from copper smelting sites of the Aravah Valley enable us to pinpoint the introduction of domestic camels to the southern Levant more precisely based on stratigraphic contexts associated with an extensive suite of radiocarbon dates. The data indicate that this event occurred not earlier than the last third of the 10th century BCE and most probably during this time. The coincidence of this event with a major reorganization of the copper industry of the region - attributed to the results of the campaign of Pharaoh Shoshenq I - raises the possibility that the two were connected, and that camels were introduced as part of the efforts to improve efficiency by facilitating trade."

 

MILITARY USES

By at least 1200 BC, the first camel saddles had appeared, and Bactrian camels could be ridden. The first saddle was positioned to the back of the camel, and control of the Bactrian camel was exercised by means of a stick. However, between 500–100 BC, Bactrian camels attained military use. New saddles, which were inflexible and bent, were put over the humps and divided the rider's weight over the animal. In the seventh century BC, the military Arabian saddle appeared, which improved the saddle design again slightly.

 

Camel cavalries have been used in wars throughout Africa, the Middle East, and into modern-day Border Security Force of India (though as of July 2012, the BSF has planned the replacement of camels with ATVs). The first use of camel cavalries was in the Battle of Qarqar in 853 BC. Armies have also used camels as freight animals instead of horses and mules.

In the East Roman Empire, the Romans used auxiliary forces known as dromedarii, whom they recruited in desert provinces. The camels were used mostly in combat because of their ability to scare off horses at close ranges (horses are afraid of the camels' scent), a quality famously employed by the Achaemenid Persians when fighting Lydia in the Battle of Thymbra.

 

19th and 20th CENTURIES

The United States Army established the U.S. Camel Corps, which was stationed in California in the late 19th century. One may still see stables at the Benicia Arsenal in Benicia, California, where they nowadays serve as the Benicia Historical Museum. Though the experimental use of camels was seen as a success (John B. Floyd, Secretary of War in 1858, recommended that funds be allocated towards obtaining a thousand more camels), the outbreak of the American Civil War saw the end of the Camel Corps: Texas became part of the Confederacy, and most of the camels were left to wander away into the desert.

 

France created a méhariste camel corps in 1912 as part of the Armée d'Afrique in the Sahara in order to exercise greater control over the camel-riding Tuareg and Arab insurgents, as previous efforts to defeat them on foot had failed. The camel-mounted units remained in service until the end of French rule over Algeria in 1962.

 

In 1916, the British created the Imperial Camel Corps. It was originally used to fight the Senussi, but was later used in the Sinai and Palestine Campaign in World War I. The Imperial Camel Corps comprised infantrymen mounted on camels for movement across desert, though they dismounted at battle sites and fought on foot. After July 1918, the Corps began to become run down, receiving no new reinforcements, and was formally disbanded in 1919.

 

In World War I, the British Army also created the Egyptian Camel Transport Corps, which consisted of a group of Egyptian camel drivers and their camels. The Corps supported British war operations in Sinai, Palestine, and Syria by transporting supplies to the troops.

 

The Somaliland Camel Corps was created by colonial authorities in British Somaliland in 1912; it was disbanded in 1944.

 

Bactrian camels were used by Romanian forces during World War II in the Caucasian region.

 

The Bikaner Camel Corps of British India fought alongside the British Indian Army in World Wars I and II.

 

The Tropas Nómadas (Nomad Troops) were an auxiliary regiment of Sahrawi tribesmen serving in the colonial army in Spanish Sahara (today Western Sahara). Operational from the 1930s until the end of the Spanish presence in the territory in 1975, the Tropas Nómadas were equipped with small arms and led by Spanish officers. The unit guarded outposts and sometimes conducted patrols on camelback.

 

FOOD USES

DAIRY

Camel milk is a staple food of desert nomad tribes and is sometimes considered a meal in and of itself; a nomad can live on only camel milk for almost a month. Camel milk is rich in vitamins, minerals, proteins, and immunoglobulins; compared to cow's milk, it is lower in fat and lactose, and higher in potassium, iron, and vitamin C. Bedouins believe the curative powers of camel milk are enhanced if the camel's diet consists of certain desert plants. Camel milk can readily be made into a drinkable yogurt, as well as butter or cheese, though the yields for cheese tend to be low.

 

Camel milk cannot be made into butter by the traditional churning method. It can be made if it is soured first, churned, and a clarifying agent is then added. Until recently, camel milk could not be made into camel cheese because rennet was unable to coagulate the milk proteins to allow the collection of curds. Developing less wasteful uses of the milk, the FAO commissioned Professor J.P. Ramet of the École Nationale Supérieure d'Agronomie et des Industries Alimentaires, who was able to produce curdling by the addition of calcium phosphate and vegetable rennet. The cheese produced from this process has low levels of cholesterol and is easy to digest, even for the lactose intolerant. The sale of camel cheese is limited owing to the small output of the few dairies producing camel cheese and the absence of camel cheese in local (West African) markets. Cheese imports from countries that traditionally breed camels are difficult to obtain due to restrictions on dairy imports from these regions.

 

Additionally, camel milk has been made into ice cream in a Netherlands camel farm.

 

MEAT

A camel carcass can provide a substantial amount of meat. The male dromedary carcass can weigh 300–400 kg, while the carcass of a male Bactrian can weigh up to 650 kg. The carcass of a female dromedary weighs less than the male, ranging between 250 and 350 kg. The brisket, ribs and loin are among the preferred parts, and the hump is considered a delicacy. The hump contains "white and sickly fat", which can be used to make the khli (preserved meat) of mutton, beef, or camel. Camel meat is reported to taste like coarse beef, but older camels can prove to be very tough, although camel meat becomes more tender the more it is cooked. The Abu Dhabi Officers' Club serves a camel burger mixed with beef or lamb fat in order to improve the texture and taste. In Karachi, Pakistan, some restaurants prepare nihari from camel meat. In Syria and Egypt, there are specialist camel butchers.

 

Camel meat has been eaten for centuries. It has been recorded by ancient Greek writers as an available dish at banquets in ancient Persia, usually roasted whole. The ancient Roman emperor Heliogabalus enjoyed camel's heel.[31] Camel meat is still eaten in certain regions, including Eritrea, Somalia, Djibouti, Saudi Arabia, Egypt, Syria, Libya, Sudan, Ethiopia, Kazakhstan, and other arid regions where alternative forms of protein may be limited or where camel meat has had a long cultural history. Camel blood is also consumable, as is the case among pastoralists in northern Kenya, where camel blood is drunk with milk and acts as a key source of iron, vitamin D, salts and minerals. Camel meat is also occasionally found in Australian cuisine: for example, a camel lasagna is available in Alice Springs.

 

A 2005 report issued jointly by the Saudi Ministry of Health and the United States Centers for Disease Control and Prevention details cases of human bubonic plague resulting from the ingestion of raw camel liver.

 

RELIGION

ISLAM

Camel meat is halal for Muslims. However, according to some Islamic schools of thought, a state of impurity is brought on by the consumption of it. Consequently, these schools hold that Muslims must perform wudhu (ablution) before the next time they pray after eating camel meat.

 

Also, some Islamic schools of thought consider it haraam for a Muslim to perform salat in places where camels lie, as it is said to be a dwelling place of shaytan.

 

According to Suni ahadith collected by Bukhari and Muslim, Muhammad ordered a certain group of people to drink camel milk and urine as a medicine. However, according to Abū Ḥanīfa, the drinking of camel urine, while not forbidden (ḥaram), is disliked (makrūh) in Islam.

 

Camel urine is sold as traditional medicine in shops in Saudi Arabia. The Sunni scholar Muhammad Al-Munajjid's IslamQA.info recommends camel urine as beneficial to curing certain diseases and to human health and cited Ahadith and scientific studies as justification. King Abdulaziz University researcher Dr. Faten Abdel-Rajman Khorshid has claimed that cancer and other diseases could be treated with camel urine as recommended by the Prophet. The United Arab Emirates "Arab Science and Technology Foundation" reported that cancer could be treated with camel urine. Camel urine was also prescribed as a treatment by Zaghloul El-Naggar, a religious scholar. Camel urine is the only urine which is permitted to be drunk according to the Hanbali madhhab of Sunni Islam. The World Health Organization said that camel urine consumption may be a factor in the spread of the MERS virus in Saudi Arabia. The Gulf Times writer Ahmad al-Sayyed wrote that various afflictions are dealt with camel urine by people. Dandruff, scalp ailments, hair, sores, and wounds were recommended to be treated with camel urine by Ibn Sina. Arab American University Professor of Cell Biology and Immunology Bashar Saad (PhD) along with Omar Said (PhD) wrote that medicinal use of camel urine is approved of and promoted by Islam since it was recommended by the prophet. A test on mice found that cytotoxic effects similar to cyclophosphamide were induced on bone marrow by camel urine. Besides for consumption as a medicinal drink, camel urine is believed to help treat hair. Bites from insects were warded off with camel urine, which also served as a shampoo. Camel urine is also used to help treat asthma, infections, treat hair, sores, hair growth and boost libido.

 

Several Sunni Ahadith mention drinking camel urine. Some Shia criticized Wahhabis for camel urine treatment. Shia scholars also recommend the medicinal use of camel urine. Shia Hadith on Imam Ja'far al-Sadiq reported that shortness of breath (asthma) was treated with camel urine. Shia Marja Ayatollah Sistani said that for medicinal purposes only, sheep, cow, and camel urine can be drunk.

 

JUDAISM

According to Jewish tradition, camel meat and milk are not kosher. Camels possess only one of the two kosher criteria; although they chew their cud, they do not possess cloven hooves:

 

Nevertheless these shall ye not eat of them that only chew the cud, or of them that only part the hoof: the camel, because he cheweth the cud but parteth not the hoof, he is unclean unto you.

— Leviticus 11:4

 

DISTRIBUTION ANDNUMBERS

There are around 14 million camels alive as of 2010, with 90% being dromedaries. Dromedaries alive today are domesticated animals (mostly living in the Horn of Africa, the Sahel, Maghreb, Middle East and South Asia). The Horn region alone has the largest concentration of camels in the world, where the dromedaries constitute an important part of local nomadic life. They provide nomadic people in Somalia (which has the largest camel herd in the world) and Ethiopia with milk, food, and transportation.

 

The Bactrian camel is, as of 2010, reduced to an estimated 1.4 million animals, most of which are domesticated. The only truly wild Bactrian camels, of which there are less than one thousand, are thought to inhabit the Gobi Desert in China and Mongolia.

 

The largest population of feral camels is in Australia. There are around 700,000 feral dromedary camels in central parts of Australia, descended from those introduced as a method of transport in the 19th and early 20th centuries. This population is growing about 8% per year. Representatives of the Australian government have culled more than 100,000 of the animals in part because the camels use too much of the limited resources needed by sheep farmers.

 

A small population of introduced camels, dromedaries and Bactrians, wandered through Southwest United States after having been imported in the 1800s as part of the U.S. Camel Corps experiment. When the project ended, they were used as draft animals in mines and escaped or were released. Twenty-five U.S. camels were bought and imported to Canada during the Cariboo Gold Rush.

 

WIKIPEDIA

This fleeting scene on Sombrero Chino (Chinese Hat) provided a blink-of-the-eye impression of the western Galapagos Islands: Galápagos Penguins (Sphensicus mendiculus) preened as they warmed up on sun-heated, guano-coated lava after feeding in the cold, food-rich water that upwells from the Pacific Ocean’s west-to-east Cromwell Current (Pacific Equatorial Countercurrent); a Brown Pelican (Pelecanus occidentalis urinator) took off with freshly-caught fish in its pouch; airborne Brown Noddies (Anous stolidus), which nest on ledges near the water’s edge, flew looking for small fish to pluck from the water’s surface; lava displayed many colors; a ship (the National Geographic Endeavor) bore excursions of a dozen or fewer naturalist-guided tourists; Pacific water displayed subtle gradations of blue; and arid islets (southern members of the Bainbridge Rocks) populated the horizon. Sombrero Chino (Chinese Hat), Galápagos, Ecuador, 05 February 2015. Panasonic Lumix DMC-TS5, Gary Glen Price, Capture One Pro.

2015-02-05b Sombrero Chino Lumix P1000340 Momentary Mosaic.jpg

The arctic fox (Vulpes lagopus, formerly known as Alopex lagopus), also known as the white fox, polar fox or snow fox, is a small fox native to Arctic regions of the Northern Hemisphere and is common throughout the Arctic tundra biome. The Greek word alopex, (ἀλώπηξ) means a fox and Vulpes is the Latin version. Lagopus is derived from Ancient Greek lago (λαγως), meaning "hare", + pous (πους), "foot" and refers to the hair on its feet. Although it has previously been assigned to its own genus Alopex, genetic evidence places it in Vulpes (Mammal Species of the World) with the majority of the other foxes.

 

The arctic fox lives in some of the most frigid extremes on the planet. Among its adaptations for cold survival are its deep, thick fur, a system of countercurrent heat exchange in the circulation of paws to retain core temperature, and a good supply of body fat. The fox has a low surface area to volume ratio, as evidenced by its generally rounded body shape, short muzzle and legs, and short, thick ears. Since less of its surface area is exposed to the arctic cold, less heat escapes the body. Its furry paws allow it to walk on ice in search of food. The arctic fox has such keen hearing that it can precisely locate the position of prey under the snow. When it finds prey, it pounces and punches through the snow to catch its victim. Its fur changes colour with the seasons: in the winter it is white to blend in with snow, while in the summer it is brown.

 

The arctic fox will generally eat any small animal it can find: lemmings, voles, hares, owls, eggs, and carrion, etc. Lemmings are the most common prey. A family of foxes can eat dozens of lemmings each day. During April and May the arctic fox also preys on ringed seal pups when the young animals are confined to a snow den and are relatively helpless. Fish beneath the ice are also part of its diet. They also consume berries and seaweed and may thus be considered omnivores. It is a significant bird egg predator, excepting those of the largest tundra bird species. If there is an overabundance of food hunted, the arctic fox will bury what the family cannot eat. When its normal prey is scarce, the arctic fox scavenges the leftovers and even feces of larger predators, such as the polar bear, even though the bear's prey includes the arctic fox itself.

 

The arctic fox has a circumpolar range, meaning that it is found throughout the entire Arctic, including the outer edges of Greenland, Russia, Canada, Alaska, and Svalbard, as well as in Subarctic and alpine areas, such as Iceland and mainland alpine Scandinavia. The conservation status of the species is good, except for the Scandinavian mainland population. It is acutely endangered there, despite decades of legal protection from hunting and persecution. The total population estimate in all of Norway, Sweden and Finland is a mere 120 adult individuals.

 

The arctic fox is the only native land mammal to Iceland. It came to the isolated North Atlantic island at the end of the last ice age, walking over the frozen sea. The Arctic Fox Center in Súðavík contains an exhibition on the arctic fox and conducts studies on the influence of tourism on the population.

 

The abundance of the arctic fox species tends to fluctuate in a cycle along with the population of lemmings and voles (a 3-to-4-year cycle). Because the fox reproduces very quickly and often dies young, population levels are not seriously affected by trapping. The arctic fox has, nonetheless, been eradicated from many areas where humans are settled.

 

The pelts of arctic foxes with a slate blue coloration—an expression of a recessive gene—were especially valuable. They were transported to various previously fox-free Aleutian Islands during the 1920s. The program was successful in terms of increasing the population of blue foxes, but their predation of Aleutian Canadian geese conflicted with the goal of preserving that species.

 

The arctic fox is losing ground to the larger red fox. This has been attributed to climate change—the camouflage value of its lighter coat decreases with less snow cover. Red foxes dominate where their ranges begin to overlap by killing arctic foxes and their kits. An alternate explanation of the red fox's gains involves the gray wolf: Historically, it has kept red fox numbers down, but as the wolf has been hunted to near extinction in much of its former range, the red fox population has grown larger, and it has taken over the niche of top predator.[citation needed] In areas of northern Europe, there are programs in place that allow hunting of the red fox in the arctic fox's previous range.

 

As with many other game species, the best sources of historical and large scale population data are hunting bag records and questionnaires. There are several potential sources of error in such data collections. In addition, numbers vary widely between years due to the large population fluctuations. However, the total population of the arctic fox must be in the order of several hundred thousand animals.

 

The world population is thus not endangered, but two arctic fox subpopulations are. One is on Medny Island (Commander Islands, Russia), which was reduced by some 85-90%, to around 90 animals, as a result of mange caused by an ear tick introduced by dogs in the 1970s. The population is currently under treatment with antiparasitic drugs, but the result is still uncertain.

 

The other threatened population is the one in Fennoscandia (Norway, Sweden, Finland and Kola Peninsula). This population decreased drastically around the start of the 20th century as a result of extreme fur prices which caused severe hunting also during population lows. The population has remained at a low density for more than 90 years, with additional reductions during the last decade. The total population estimate for 1997 is around 60 adults in Sweden, 11 adults in Finland and 50 in Norway. From Kola, there are indications of a similar situation, suggesting a population of around 20 adults. The Fennoscandian population thus numbers a total of 140 breeding adults. Even after local lemming peaks, the arctic fox population tends to collapse back to levels dangerously close to non-viability.

 

The arctic fox is classed as a "prohibited new organism" under New Zealand's Hazardous Substances and New Organisms Act 1996 preventing it from being imported into the country

 

Maryland Zoo, Baltimore Md.

Davis Strait, Canada

 

Taken on August 30, 2018 (uploaded 1/9/19)

 

The strait was first explored by John DAVIS, leader of three voyages 1585-87 organized by merchants of London, England.

 

www.thecanadianencyclopedia.ca/en/article/davis-strait

 

Davis Strait, situated between BAFFIN ISLAND and Greenland, is the entrance to BAFFIN BAY from the North Atlantic. It is a large stretch of water over 950 km across at its greatest width and never less than 300 km wide. At the narrowest point, its submarine topography consists of an undersea ridge, a continuation of the mid-Labrador ridge, extending from the coast of Baffin Island to Greenland. The shallowest waters in the strait are found along this sill, from 350 to 550 m deep, before plunging down to abyssal basins on either side.

 

Some of the greatest depths in the eastern Arctic are reached here (3660 m) in the southern end of the strait. The surface waters are strongly affected by counterclockwise-flowing currents.

 

Along the west side, an outflow of cold water from the Arctic Basin moves south, at flow velocities of 8-20 km/day, to feed the Labrador current. On the east side the west Greenland countercurrent brings warmer water north. Ice conditions reflect this flow regime, with heavy ice movement and icebergs along the western shore, contrasting sharply with more open water along the Greenland side.