“Song Thrasher” at LLC

John Callender

I haven’t seen this bird myself, but apparently there is a Song Sparrow at Lake Los Carneros that has an abnormally long upper beak that curves downward, making Marge and Don Thornton, who saw the bird near the east end of the dam on September 23, say it looks at first glance like “a miniature thrasher.” You can see their photo in their eBird list here:


Today Jacob Broad photographed what looks like the same bird. His photos are here:


I wonder what might have caused the deformity, what problems it creates for the bird, and whether the beak will continue to grow in the future.

John Callender

John Callender

A quick followup to share some information someone was kind enough to forward to me. This appears to be a condition called “Avian Keratin Disorder”, or AKD, first described in chickadees in Alaska in the 1990s. Recent research suggests it may be caused by a virus. More information at the links below (including a link to a form for reporting birds with the condition; I’ve taken the liberty of submitting a report for this bird already based on the two eBird lists).



John Callender

Barbara Goll <b37g@...>

Photo of "Song Thrasher"

Hope this helps.

Barbara Goll