Deformed bills Tufted Titmouse with deformed bill by Laurie Dirkx, Ontario, New York Sometimes FeederWatchers observe birds with odd looking bills. Scientists are studying this phenomenon in Alaska, where the problem seems to be most prevalent. From 2000 through 2006 Project FeederWatch collected 215 reports of bill deformities, representing 38 species from 38 states and provinces. Black-capped Chickadees were reported most frequently, making up 30% of the reports. House Finches were reported the second most frequently with 21% of reports. The majority of bill deformity reports came from Alaska–31% of all reports received, while 12% of reports came from California, the state with the second highest total. FeederWatch provided summaries of reported bill deformities to researchers at the United States Geological Survey’s Alaska Biological Science Center. Black-capped Chickadee with deformed bill by Daniel Quick, Soldotna, Alaska Biologists there have been studying bill deformities, also known as Avian Keratin Disorder, for some time. In 2016 a team of researchers from the California Academy of Sciences, University of California San Francisco, and the USGS identified a novel virus that has been linked to Avian Keratin Disorder. Learn more about the research.