Brown Bear

The brown bear (Ursus arctos) is a large bear distributed across much of northern Eurasia and North America. It can weigh from 300 to 780 kilograms (660 to 1,700 lb) and its largest subspecies, the Kodiak Bear, rivals the polar bear as the largest member of the bear family and as the largest land-based predator.

 

There are several recognized subspecies within the brown bear species. In North America, two types are generally recognized, the coastal brown bear and the inland grizzly, and the two types could broadly define all brown bear subspecies. Grizzlies weigh as little as 350 lb (159 kg) in Yukon, while a brown bear, living on a steady, nutritious diet of spawning salmon, from coastal Alaska and Russia can weigh 1,500 lb (682 kg). The exact number of overall brown subspecies remains in debate.

 

While the brown bear's range has shrunk, and it has faced local extinctions, it remains listed as a least concern species by the IUCN, with a total population of approximately 200,000. Its principal range countries are Russia, the United States (mostly in Alaska), Canada, the Carpathian region (especially Romania, but also Ukraine, Slovakia, and so on), the Balkans, Sweden and Finland, where it is the national animal. The brown bear is the most widely distributed of all bears.

 

Brown bears have very large and curved claws, those present on the forelimbs being longer than those on the hind limbs. They may reach 5 to 6 centimetres (2.0 to 2.4 in) and sometimes 7 to 10 centimetres (2.8 to 3.9 in) along the curve. They are generally dark with a light tip, with some forms having completely light claws. Brown bear claws are longer and straighter than those of American black bears. The claws are blunt, while those of a black bear are sharp.

 

Adults have massive, heavily built concave skulls, which are large in proportion to the body. The forehead is high and rises steeply. The projections of the skull are well developed when compared to those of Asian black bears: the latter have sagittal crests not exceeding more than 19–20% of the total length of the skull, while the former have sagittal crests comprising up to 40–41% of the skull's length. Skull projections are more weakly developed in females than in males. The braincase is relatively small and elongated. There is a great deal of geographical variation in the skull, and presents itself chiefly in dimensions. Grizzlies, for example, tend to have flatter profiles than European and coastal American brown bears. Skull lengths of Russian bears tend to be 31.5 to 45.5 centimetres (12.4 to 17.9 in) for males, and 27.5 to 39.7 centimetres (10.8 to 15.6 in) for females. The width of the zygomatic arches in males is 17.5 to 27.7 centimetres (6.9 to 11 in), and 14.7 to 24.7 centimetres (5.8 to 9.7 in) in females. Brown bears have very strong teeth: the incisors are relatively big and the canine teeth are large, the lower ones being strongly curved. The first three molars of the upper jaw are underdeveloped and single crowned with one root. The second upper molar is smaller than the others, and is usually absent in adults. It is usually lost at an early age, leaving no trace of the alveolus in the jaw. The first three molars of the lower jaw are very weak, and are often lost at an early age. Although they have powerful jaws, brown bear jaws are incapable of breaking large bones with the ease of spotted hyenas.

 

The dimensions of brown bears fluctuate very greatly according to sex, age, individual, geographic location, and season. The normal range of physical dimensions for a brown bear is a head-and-body length of 1.7 to 2.8 meters (5.6 to 9.2 ft) and a shoulder height of 90 to 150 centimeters (35–60 in). The smallest subspecies is the Eurasian brown bear, whose mature females weigh as little as 90 kg (200 lb). Barely larger, grizzly bears from the Yukon region (which are a third smaller than most grizzlies) can weigh as little as 100 kg (220 lb) in the spring and the Syrian brown bear, with mature females weighing as little as 150 kg (330 lb). The largest subspecies are the Kodiak bear, Siberian brown bear, and the bears from coastal Russia, Alaska, and British Columbia. It is not unusual for large males in coastal regions to stand over 3 m (9.8 ft) while on their hind legs, and to weigh up to 680 kg (1,500 lb). The heaviest recorded brown bear weighed over 1,150 kilograms (2,500 lb).

 

Brown bears have long, thick fur, with a moderately long mane at the back of the neck. In India, brown bears can be reddish with silver tips, while in China, brown bears are bicolored with a yellow-brown or whitish cape across the shoulders. North American grizzlies can be dark brown (almost black) to cream (almost white) or yellowish brown. Black hairs usually have white tips. The winter fur is very thick and long, especially in northern subspecies, and can reach 11 to 12 centimetres (4 to 5 in) at the withers. The winter hairs are thin, yet rough to the touch. The summer fur is much shorter and sparser, and its length and density varies geographically.

 

The brown bear is primarily nocturnal. In the summer, it gains up to 180 kilograms (400 lb) of fat, on which it relies to make it through winter, when it becomes very lethargic. Although they are not full hibernators, and can be woken easily; both sexes like to den in a protected spot, such as a cave, crevice, or hollow log, during the winter months. Brown bears are mostly solitary, although they may gather in large numbers at major food sources and form social hierarchies based on age and size. Adult male bears are particularly aggressive and are avoided by adolescent and subadult males. Female bears with cubs rival adult males in aggression, and are more intolerant of other bears than single females. Young adolescent males tend to be least aggressive, and have been observed in nonagonistic interactions with each other. In his Great Bear Almanac, Gary Brown lists 11 different sounds bears produce in 9 different contexts. Sounds expressing anger or aggravation include growls, roars, woofs, champs and smacks, while sounds expressing nervousness or pain include woofs, grunts and bawls. Sows will bleat or hum when communicating with their cubs.

 

They are omnivores and feed on a variety of plant products, including berries, roots, and sprouts, and fungi, as well as meat products such as fish, insects, and small mammals. Despite their reputation, most brown bears are not highly carnivorous, as they derive up to 90% of their dietary food energy from vegetable matter. Their jaw structure has evolved to fit their dietary habits. Their diet varies enormously throughout their differing areas based on opportunity. For example, bears in Yellowstone eat an enormous number of moths during the summer, sometimes as many as 40,000 in a day, and may derive up to half of their annual food energy from these insects. In some areas of Russia and Alaska, brown bears feed mostly on spawning salmon, whose nutrition and abundance explain the enormous size of the bears in these areas. Brown bears also occasionally prey on large mammals, such as deer (including elk, moose and caribou), bighorn sheep, mountain goats, bison and muskoxen. When brown bears attack these animals, they tend to choose the young ones, as they are easier to catch. When hunting, the bear pins its prey to the ground and then tears and eats it alive. On rare occasions, bears kill by hitting their prey with their powerful forearms, which can break the necks and backs of large prey, such as moose. They also feed on carrion, and use their size to intimidate other predators, such as wolves, cougars, tigers, and black bears from their kills.

 

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