Thursday, September 18, 2008

Bald birds

Joe's comment on my last post reminded me that it's that time of year to address the perennial bald bird issue. It is one of the most frequently asked questions about birds. Northern Cardinals (Cardinalis cardinalis), Blue Jays (Cyanocitta cristata), and Common Grackles (Quiscalus quiscula) are the most common victims of this disturbing-looking feather loss.

There's nothing wrong with most of these birds, despite how bad they look. All birds replace all of their feathers at least once a year, and fall is often the time that North American birds undergo this complete molt. Typically, this molt takes place over a few weeks. But some individuals, unfortunately, lose all the feathers on their head at the same time.

I've often read that ectoparasites such as feather mites are responsible for this condition. I have never found mites on bald birds that I've banded. All birds have some of these mites -- they feed on oils, fungi, and bits of skin, and don't cause feather loss. It would also be unlikely, if not impossible, that they would cause all the feathers in one area to fall out simultaneously. In fact, they typically move to tail and wing feathers -- cooler locations on the bird's body -- in warm weather such as is typical in fall.

There are a couple of other types of mites found on birds, but they have not been found on bald birds. My search for information on quill mites, for instance, didn't even turn up any evidence that they've been found on cardinals or jays. Nor does it make sense that these other mites would cause feather loss on the head but not elsewhere, since birds are not able to remove them easily from anywhere on their bodies via normal preening.

Although the role of mites in bird baldness has not been thoroughly studied, the seasonal and localized nature of the baldness and the fact that it is most common in a relatively limited number of bird species leads me to believe that their presence is coincidental and not causative. That this catastrophic molt is "normal" in at least some individual birds comes from Cornell staffer and former wildlife rehabber Laura Erickson. She was in charge of a Blue Jay in captivity that always lost all the feathers on its head simultaneously once a year -- for the 8 years she had it!

Sometimes bald birds are seen at other times of the year when they would not be expected to be molting. The reason for their feather loss may be different (running into a window, for instance, could cause at least a temporary loss).

Being bald is not harmful to birds, except perhaps in cold or wet weather. Within a few weeks, the feathers will grow back.

For more photos and information, see the Cornell web site. Top photo of a bald cardinal by Jimmy Smith.

Janet Hug from Commerce Twp., MI sends us this photo of an adult male cardinal at her feeder, on the road to refeathering, but still looking pretty shabby.


Janet said...

I have a bald male cardinal visiting my Commerce Twp. backyard feeder. A few weeks ago, I had a bald blue jay showing the same balding head pattern. They are acting like their normal vigorous selves.

Julie Craves said...

I'll add really good photos of bald birds to the post, with credit, if you want to send them to jac DOT rrbo AT gmail DOT com

Janet said...

The male cardinal is looking much better since the last photo I took of him. His crest is almost fully grown. He is still a bit camera shy for a photo.

Amy said...

I have a bald cardinal right now...June '09. Not typical molting season, and there actually may be 2 of them. I'm trying to compare photos days apart.

Sherry said...

June 5, 2009, Central Illinois I saw a bald-headed cardinal come to our bird feeder. First time I've ever seen this. I'm gonna try to get a picture. He's skittish around feeder.

D said...

I have 3 bald birds visiting our northwest Ohio feeders. Last week I first saw 2 different bald Cardinals. They are still around, and then yesterday and again today, I've also seen a bald Grackle. Since I'd never seen a bald bird before last week, having 3 seems very odd in spite of what I read about it being a normal occurrence. I have photos, if anyone is interested.

Julie Craves said...

D -- it's not too unusual to see several in the same time frame. This is the time when many species are starting their fall molt.

Julie Zickefoose said...

Thank you so much for this analysis. I've been among those passing along the feather mites cause bald cardinals fable, and I'd be thrilled if I could tell people it's a normal process. I've always wondered why the feathers grow back by winter, if it is indeed caused by mites. Why would the mites die in cold weather, if they're crawling around on a warm bird? And mites being too small to be preened out, why would the just-so-story about birds not being able to preen their heads, hence that's where the feathers fall out, be true? Another thing I wondered about was this: If head plumage was chewed off by mites, why did their body plumage still look good? Just sorry it took me this long to stumble across your post.