Wednesday, October 8, 2014

Downy Woodpecker Deformed Bill

On 9 June 2014 I banded a male Downy Woodpecker with a deformed, elongated bill. Having previously banded a Black-capped Chickadee with a deformed bill, this woodpecker record is my second for deformed bills at our Dundas banding station. reports that an Alaskan study found 25 species with deformities. Contrary to that report, none of the Alaskan birds were first-year birds (Van Hemert, pers. com.). Other banding studies found that deformities develop in birds between six months and two years of age. My woodpecker was over two years old, as evidenced by its black primary coverts (but, of course, this age does not indicate when the bill began developing abnormally).  This woodpecker does not seem to be in very good health, its feathers are soiled and its weepy eye is surrounding by missing feathers. I have not recaptured or seen this individual since the initial banding.

What causes bird to develop abnormal bills is not known. Hypotheses run from injury, disease, parasites, poor nutrition, genetic defects, exposure to contaminants, and exposure to extreme heat (

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