West Nile Virus Killing Backyard Birds

By Dan Shapley News Editor Common birds that frequent backyard feeders are succumbing to West Nile virus, leading to significant declines in several species beloved by homeowners, according to new research. The findings also highlight the tight relationship between human and environmental health, and the increasingly global nature of epidemics, experts said. West Nile virus is primarily a wildlife disease, spread bird-to-bird by mosquitoes. Yet it has killed nearly 1,000 Americans and sickened thousands more. West Nile virus originated in the Middle East and first appeared in the Western Hemisphere in New York in 1999. With global trade and travel common, diseases like West Nile virus can spread easily around the world, where oceans and mountain ranges once stood as barriers. “People are beginning to understand that environmental change has health consequences, and that our health depends on ecosystem health. That''s not something we''re used to thinking about,” said Mary Pearl, president of Wildlife Trust, which has pioneered the study of conservation medicine. Scientists have long known that the virus killed crows, blue jays and closely related birds. The new study, published today in Nature, found that several other common species are also suffering. Chickadees, tufted titmice, American robins, house wrens and Eastern bluebirds have also declined as the disease has spread across the United States. No species has been affected more than crows, which in some regions have declined by 45 percent. When scientists consider the upward trajectory of the crow population prior to the emergence of West Nile virus, the loss could be higher than 60 percent. “While I wouldn''t expect these species to be endangered, there are really huge impacts on these species and whole ecosystem processes,” said Marm Kilpatrick, a senior scientist for the Consortium for Conservation Medicine. The rate of decline for other species was similar, if not as dramatic, as it was for crows. And the scientists say their findings may well be conservative. They relied on the annual atlas of breeding birds, a citizen science program that for 26 years has cataloged birds primarily in suburban and rural areas. Because West Nile virus is primarily spread by a mosquito that thrives in urban settings, and many of the birds that are most affected also thrive in urban settings, the data may underestimate the toll on city birds. And there are many species of birds that have yet to be studied. Kilpatrick said it''s likely that raptors like hawks and owls are suffering, but there's sparse data to test the hypothesis. In New York, the state wildlife pathologist, Ward Stone, has examined many birds that have died from West Nile virus, and his observations suggest additional species are in decline due to West Nile virus. “It''s not uncommon to see it in red tailed hawks, great horned owls, and some of the little raptors like sharp-shinned and Cooper''s hawks,” Stone said. “We see it in all kinds of birds.” Want to help? Here are four things you can do to help the birds. Related Stories Common Birds In Drastic Decline List Of 20 Common Birds In Decline 'I Saw The Ivory-Billed Woodpecker' Disease Attacks Birds At Backyard Feeders Tips For Preventing Disease At Feeders