BIRD COLUMN FOR February 22, 2004
By Benjamin P. Burtt
Here is a question from J.B. of Atlanta, Georgia who reads my column on line. In 1974 he was in my Chemistry class at Syracuse University and now teaches science in a private school in Atlanta.
He asked: I have seen several cardinals that had no feathers on their heads, one several years ago and one this year. Can you tell me something about this condition?
Dear J.B.:----Bald cardinals and jays are reported nearly every year in the late summer. Without feathers on the head, the bird resembles a tiny vulture. At the time, the feathers on the rest of the body are usually dull and worn looking.
Those of us who write on birds for newspapers or magazines receive questions about bald birds from time to time. I would guess that someone asks me about this almost every year. As far as I can determine, this matter has not been studied carefully. However, your question did prompt me to see if I could learn more about it.
There are several things that we do know.
1. It is observed most often with blue jays and cardinals.
2. When we can recognize adults and young, it is the adults that
show this condition.
3. Such birds are usually spotted in the summer.
4. Only a small percentage of each species shows this condition.
On the basis of the information summarized below, I have concluded that in most cases it is related to the way certain individual birds molt their head feathers. For those particular birds it is their normal process, but it differs from the way most individuals of their species undergo the molt.
The molting process
To understand the bald headed bird phenomenon we must learn something about feathers and the molting process.
Once a feather has grown to full size, it is no longer connected to the blood supply. So it gradually wears out. If it is broken of frayed, it cannot be repaired. So each bird must get a new set of feathers every year.
This takes place in late summer after the breeding is over. Adult birds lose all their feathers gradually and new ones grow in before fall.
If a feather is accidentally pulled out, a new one will grow right away even though it is not the molting season.
Birds born in the spring also molt in the late summer, but they replace only their body and head feathers. Those on the wing and tail are not replaced until the following summer.
For the blue jay and cardinal and for most songbirds, the wing feathers are lost one at a time from each wing. New feathers replace them before other wing feathers drop out. Thus the bird maintains its ability to fly. The tail feathers are lost slowly, a few at a time. This ensures that the tail will be able carry out its functions while the bird is flying.
However, on the body, many of the feathers can be lost simultaneously so there were will be patches where the feathers are scarce. The bird looks ragged and unkempt when both new and old feathers are present. Usually, the feather cover is thin, but seldom is a large patch of bare skin visible.
Among the blue jays, cardinals and grackles there are occasional individuals that shed most of their head feathers all at once. The blue jay in this sketch shows how such a bird would appear.
Within a week, much of the bare skin will be covered and in two weeks the head will be covered with feathers again.
The molting of the feathers all over the body and wings for the blue jay lasts about six weeks, starting in July. For most jays, the body and head feathers are lost from scattered locations here and there. During this process the skin is covered, but the coating is not very thick.
During July through August, the growing of all those feathers is a physiological drain on the bird. It needs more food to grow the feathers and to compensate for the heat lost due to the decreased insulation.
At this time the bird usually is less active. Singing and fighting stop. The bird skulks and hides. We may not see much of it as it conserves energy during this period while the feathers are being replaced.
All birds have this late summer molt. Many species have a second molt when they grow new feathers in the spring before they breed. Often this results in brilliant, new colors.
Sometimes the plumage changes in the spring are brought about by wear and not by molting. For example, the black-bib of the male house sparrow develops by spring. It is produced as the tan tips of the black feathers wear away. This exposes the black part of the feathers. So the new plumage and new appearance is produced without new feathers being formed.
The blue jay has only one molt in late summer. So it looks pretty much the same throughout the year. In the spring, its feathers are worn and faded. The blue is not so brilliant and black bars are less apparent in the spring than in the fall when its feathers are new.
The summer molt for birds occurs at a time that interferes the least with activities that require a lot of flying. So it comes when breeding is over and before the fall migration.
Most birds that capture flying insects need to do a lot of flying to stock up on food before they migrate south. So they postpone their molting until they are on their wintering ground. These include most flycatchers, swifts and swallows.
The purple martin, unlike the other swallows, starts molting before migration. During its long over water flights, the molting however is suspended and then is completed after the birds arrive in South America.
Waterfowl have a different molting process.
Waterfowl lose all their wing feathers at the same time and so have a period of time when they are temporarily flightless. This does not put them in danger, because their food and shelter are in the water and the marsh where they stay during this time.
NOW BACK TO THE BALD BIRDS
A bird that loses all the feathers on its head simultaneously is the exception, and such a bird is very conspicuous, but not very often seen.
Suggestions have been made that this could be due to a problem with the diet or an infestation of mites or caused by a disease. Another idea is that it is just the way that particular bird molts. It drops all the feathers on its head at one time instead of losing them gradually as do most birds of the same species.
I now believe that there indeed are differences in the way birds lose their head feathers when undergoing the late summer molt. While most cardinals, for example, lose their head feathers gradually, a few individuals lose all the head feathers simultaneously. There is no external cause, it is just the way that particular bird molts.
To make certain of this, we really need to follow the life of one of these individual birds for several years and observe the late summer molt each year. If it is due to mites or disease or a faulty diet, it is unlikely that a bald head will be observed every year at the time of the summer molt. On the other hand, if we find that this bird loses all its head feathers simultaneously in the same way every year in the summer, then it is clear that this is the way that particular individual molts. SUCH A BIRD HAS NOW COME TO MY ATTENTION!
It was reported by Laura Erickson of Duluth, Minnesota in response to a question asked by Gerry Rising of Buffalo, NY.. He writes a bird column for the Buffalo News and a reader had asked him about a bald cardinal in 1998. He used the internet and put the question to BIRDCHAT where his question was presented to some 1300 ornithologists around the world.
Among the many responses was the one from Laura Erickson. She is an educator and was a licensed wildlife rehabilitator.
She had two blue jays in captivity for a time that could not be released to forage on their own. She used them in lectures to school children and to adults and had a permit to keep them in captivity for educational purposes.
She observed their annual molting year after year. One lost its head feathers gradually every year as do most birds. However, the other blue jay in the same cage, molted all its head feathers simultaneously every year for eight years. It was bald for a couple weeks each time until its new feathers grew in.
This was a healthy blue jay with no evidence of mites and the other blue jay in the same cage had the same environment, same food and the same lack of mites, but molted in the usual way. So here we have the perfect experiment. We have two birds in the same cage and one molts its head feathers gradually and the other drops all of them at the same time.
Here is another useful piece of evidence. Bill Hilton Jr. is the Director of the Hilton Pond Center for Piedmont Natural History in York, South Carolina. He does a lot of bird study through banding. On July 30, 2001 he captured and banded a cardinal that had recently fledged. It apparently, hung around the Nature Center and was recaptured twice in 2002 as an adult female. It was not captured during the summer molting period.
She was captured three times in 2003. In May she had normal head plumage. In July, when captured she was bald and is shown in the picture just below on the left. A close-up from that same photograph is shown on the right. You can see a single red feather sticking up from the crown. This is probably one of the feathers that are part of the tuft.
Courtesy of Bill Hilton Jr.
In October she was again captured, but with a normal appearance. All the feathers had grown back.
Hiltons cardinal observations are consistent with the hypothesis that the bird was just molting, but they do not exclude the possibility of a one time disease or infestation with mites. I hope that he can capture that bird next year during the summer molt to see if it is bald then. If it is , then I think we can rule out disease or mites in the case of this particular bird.
In the light of Laura Erickson’s and Bill Hilton’s observations, I suggest that a small percentage of cardinals and a small percentage of blue jays do normally drop all of their head feathers simultaneously during the late summer molting process. For those particular birds, this is a normal occurrence and occurs in the same way every year and the bird immediately grows a new set..
Another cardinal may simultaneously drop only the feathers on the top of the head. The feathers on the nape and the side of the head may drop gradually. Presumably, it would molt that way each year.
There are two reasons that bald birds are seldom observed. Individuals with this molting pattern are rare, perhaps one out of a hundred cardinals ( a guess) and the bird is only completely bald for such a short time that the chances of seeing it when it is bald are very small. For example, in the case of the cardinal at Hilton Pond, that was banded in 2001, it was positively identified by capturing it and reading the band six more times. Only one of those times was during the summer molt and that was the only time its head was bald.
I hope that the bird can be captured next year during the summer molt to see if it is bald then. If it is, think we can rule out disease or mites in the case of this particular bird.
Above is a side view of a bald cardinal, courtesy of Marguerite McGinnis of Buffalo, NY who snapped the photograph in Batavia, Illinois. There are no feathers on the head at all. This picture was also used by Gerry Rising in his column in the Buffalo News in 1998.
Courtesy of Ramona M. Lauda
This bald male cardinal was photographed at Falls Church, VA by Ramona M. Lauda in the late summer of 2002. She sent the photograph with a question about the bird to the Cornell Laboratory of Ornithology. It was through Cornell that I was able to obtain the image and get permission from MS. Lauda to use it here.
Further information and pertinent images may be found on the websites listed below.
Reports of bald headed birds and some photographs were sent to the people running the Feeder Watch program at Cornell. You can read an article and see some of these photographs about those birds by visiting:
http://www.birds.cornell.edu/pfw/AboutBirdsandFeeding/BaldBirds.htm
If you wish to see a larger, sharp close up of the head of the Hilton pond cardinal and read Bill Hilton’s article about his cardinal, click on this underlined address.
http://www.hiltonpond.org/ThisWeek030701.html
You can read Gerry Rising's 1998 article on the bald cardinal by visiting http://www.acsu.buffalo.edu/~insrisg/nature/nw98/baldbirds.html
I suggest that you also visit the web site of the Hilton Pond Center for Piedmont Natural History at http://www.hiltonpond.org/ It has a lot of interesting and instructive information about many aspects of nature.
Laura Erickson has a web site well worth visiting at
http://www.lauraerickson.com/
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