Mark Chapman of Fairport e-mailed me these photos, with this message: “I have noticed bluejays and cardinals in my backyard that are missing all of their head feathers. Do you have any idea what’s going on?”
The best discussion of this I’ve found is at the Cornell Laboratory of Ornithology, which devotes a page of their website to this phenomenon, in conjunction with Project FeederWatch.
“Each year FeederWatchers report several cases of ‘bald-headed birds,’ mostly Blue Jays and Northern Cardinals,” the lab notes. “One possible explanation for this phenomenon is an abnormal replacement of feathers (molt). Most bald-headed bird reports occur in summer and fall, which are typical molting times. Many of these strange-looking birds may be juveniles undergoing their first prebasic molt, which produces the first winter adult plumage. For some unknown reason, the bald birds may have dropped all of their head feathers at once. Staggered feather replacement is the normal pattern.”
Other cases of baldness may result from feather mites or lice, the lab adds, or some other environmental or nutritional factor. “But no one knows for sure, and the condition has not been well studied. Fortunately, new head feathers grow in within a few weeks.”
Go to
www.birds.cornell.edu/pfw/AboutBirdsandFeeding/BaldBirds.htm for more on this subject. In fact, go to the home page at
www.birds.cornell.edu and browse through all the links at this informative site, from profiles about individual birds to tips on feeding to projects in which amateur birders like you and me can help scientists keep track of bird populations.
