Scientists: Beak deformities increase in Northwest US
By DAN JOLING , Associated Press
November 9, 2010 (AP) — Scientists have observed the highest rate of beak abnormalities ever recorded in wild bird populations in Alaska and the Northwest, a study by two federal scientists said. The U.S. Geological Survey study on beak deformities in northwestern crows in Alaska, Washington and British Columbia follows a trend found earlier in Alaska’s black-capped chickadees. “The prevalence of these strange deformities is more than 10 times what is normally expected in a wild bird population,” said research biologist Colleen Handel. Handel and wildlife biologist Caroline Van Hemert published their findings in The Auk, a Quarterly Journal of Ornithology. They captured Alaska crows in six coastal locations and used documented reports and photographs for birds elsewhere. The cause of the deformity – called “avian keratin disorder” – hasn’t been determined, Handel said. An estimated 17 percent of adult northwestern crows are affected by the disorder in coastal Alaska. The keratin layer of the beak becomes overgrown, resulting in elongated and often crossed beaks. The deformity showed up in adults birds, most often in the upper beak but sometimes in the lower beak or both. The abnormality sometimes is accompanied by elongated claws, abnormal skin or variations in feather color. Van Hemert said the disorder first was noticed in significant numbers around 1999. It has increased dramatically over the past decade, affecting 6.5 percent of adult black-capped chickadees in Alaska annually. Biologists have documented more than 2,100 affected individuals and increasing numbers of other species, such as nuthatches and woodpeckers, have been spotted with beak deformities. …
