Formerly rare beak deformities are spreading rapidly among crows in southwestern B.C. and Puget Sound, according to researchers from the U.S. Geological Survey.
The biologists observed an unusual concentration of crows with badly overgrown beaks in Alaska beginning a little over 10 years ago. According to the scientists, a capture program in 2007 and 2008 revealed that more than 16 per cent of the Alaskan crow population was afflicted, “the highest rate of gross deformities ever recorded in a wild bird population.”
“That’s about 10 to 20 times the normal rate,” said Colleen Handel, co-author of a recent article on the phenomenon published in The Auk, a scientific journal of ornithology. “Some of us who had been working in the field for a long time had never seen anything more than a scattered incidence of this kind of deformity.”