house finches in winter
Haemorhous mexicanus on Airport Road, Dec. 5, 2023.
The large population of eastern house finches shows much less genetic diversity than the population that resides in the western states because it underwent a severe bottleneck in the 1940's. The species was originally absent from the eastern U.S. but bird breeders captured a number of pairs of birds from the western states and began selling them as cage birds in Long Island. When these commercial breeders feared that authorities would crack down on their operation, they released birds into the wild, where their population exploded over the next two decades, expanding throughout the East and becoming a common bird in suburban yards and gardens. A mycoplasma infection became established in bird feeders from which it swept across the eastern population, which due to its genetic homogeneity, was extremely vulnerable to the epidemic, which enforced another bottleneck on the eastern population. The numbers eventually recovered but we have not seen nearly as many pairs nesting in our yards in the last ten years as in previous years.
house finches in winter
Haemorhous mexicanus on Airport Road, Dec. 5, 2023.
The large population of eastern house finches shows much less genetic diversity than the population that resides in the western states because it underwent a severe bottleneck in the 1940's. The species was originally absent from the eastern U.S. but bird breeders captured a number of pairs of birds from the western states and began selling them as cage birds in Long Island. When these commercial breeders feared that authorities would crack down on their operation, they released birds into the wild, where their population exploded over the next two decades, expanding throughout the East and becoming a common bird in suburban yards and gardens. A mycoplasma infection became established in bird feeders from which it swept across the eastern population, which due to its genetic homogeneity, was extremely vulnerable to the epidemic, which enforced another bottleneck on the eastern population. The numbers eventually recovered but we have not seen nearly as many pairs nesting in our yards in the last ten years as in previous years.