Federal scientists say they're observing the highest rate of beak abnormalities ever recorded in wild bird populations in Alaska and the Northwest.
U.S. Geological Survey scientists say they haven't been able to determine the cause, but the deformed beaks could signal a growing environmental-health problem.
Research biologist Colleen Handel says the prevalence of the deformities is more than 10 times above what is normally expected in a wild bird population.
Affected birds include black-capped chickadees and northwestern crows.
Scientists call it "avian keratin disorder," in which the keratin layer of the beak becomes overgrown, resulting in elongated and often crossed beaks.
The deformities affect birds' ability to feed and clean themselves.