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Chronicle Herald, Thursday, May 17, 2007 PHOTO: Kirk Johnson, a vector ecologist at the Metropolitan Mosquito Control District in St. Paul, Minn., tests crows for the West Nile virus. (JERRY HOLT / Star Tribune) Study: West Nile virus decimates suburban birds By SETH BORENSTEIN WASHINGTON ‹ Birds that once flourished in suburban skies, including robins, bluebirds and crows, have been devastated by West Nile virus, a study found. Populations of seven species have had dramatic declines across the continent since West Nile emerged in the United States in 1999, according to a first-of-its-kind study. The research, to be published Thursday in the journal Nature, compared 26 years of bird breeding surveys to quantify what had been known anecdotally. "We¹re seeing a serious impact," said study co-author Marm Kilpatrick, a senior research scientist at the Consortium of Conservation Medicine in New York. West Nile virus, which is spread by mosquito bites, has infected 23,974 people in confirmed cases since 1999, killing 962, according to the Centers for Disease Control and Prevention. But the disease has been far deadlier for birds. The death toll for crows and jays is easily in the hundreds of thousands, based on the number of bodies found and extrapolated for what wasn¹t reported, Kilpatrick said. It hit the seven species ‹ American crow, blue jay, tufted titmouse, American robin, house wren, chickadee and Eastern bluebird ‹ hard enough to be scientifically significant. Only the blue jay and house wren bounced back, in 2005. The hardest-hit species has been the American crow. Nationwide, about one-third of crows have been killed by West Nile, said study lead author Shannon LaDeau, a research scientist at the Smithsonian Migratory Bird Center in Washington. The species was on the rise until 1999. In some places, such as Maryland, crow loss was at 45 per cent, and around Baltimore and Washington, 90 per cent, LaDeau said. While crows are scavengers and often disliked, they play a key role in nature by cleaning up animal carcasses, LaDeau noted. Researchers will next look into what species benefit from the disappearance of crows.
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