Why Do Birds Go Bald?

Why do birds go bald has a usual answer and a specific exception. The usual answer is a molt that goes slightly wrong in late summer, dropping every head feather at once instead of a few at a time, and it resolves in a couple of weeks. The exception is worth learning because it has a visible test: on a bald cardinal, the color of the exposed skin is the tell.

The underlying cause of the simultaneous head molt is not settled science, and the organizations that field these reports say so themselves.

Why does the head go bald and not the rest of the bird?

Because a normal molt is staggered, and this one is not.

Audubon, reporting the account of Emma Greig, then Project Leader of FeederWatch at the Cornell Lab of Ornithology, describes the ordinary process: The molting process normally occurs in stages, so that none of the bird's skin is left exposed. A bird replacing feathers in sequence never has a bare patch, which is why most molting is invisible from a kitchen window.

The bald case is that sequence failing: Sometimes this process goes awry, and a bird loses all the feathers on its head at once. Project FeederWatch describes the same thing from the reports it receives, noting that the affected birds have dropped their head feathers simultaneously during molting, resulting in individuals being nearly bald for about a week.

There is a reason the head is where this shows up at all, and it applies to the other cause as well. A bird preens its own body and cannot reach its own scalp, which Audubon spells out in the context of parasites: a bird will remove the offending arthropods by preening, but won't be able to reach its own head. The head is the part of a bird that its owner cannot maintain.

Which birds, and when?

Two species account for most of what gets reported, and the timing is a season rather than a date.

Project FeederWatch: Each year FeederWatchers report several cases of bald-headed birds, primarily Blue Jays and Northern Cardinals, and those reports cluster in late summer and fall. Audubon gives the reason the calendar works out that way: birds molt in these weeks, taking advantage of the down time between nesting season and migration.

Age matters too. FeederWatch: Many of these strange-looking birds may be juveniles undergoing their first prebasic molt, which produces the first winter adult plumage. Audubon reaches the same place, noting it happens most often to juvenile birds in their first molt.

The two species are not described in identical terms, and the difference is worth keeping. For one, FeederWatch calls the pattern outright normal: For Blue Jays, this molt pattern is considered normal. For the other, the claim is framed through frequency rather than expectation: this molt pattern happens with enough frequency in Northern Cardinal populations to be considered within the normal range.

If the bald bird at your feeder is neither of those two, that is itself informative. FeederWatch: If you notice a bald-headed bird of another species, it could be the result of an abnormal molt, since Staggered feather replacement is the normal pattern for most birds.

Is a bald bird sick? The check that separates the two cases

Look at the skin rather than at the missing feathers.

A molting head is bare but otherwise unremarkable. An ailing one usually is not: FeederWatch notes that baldness may result from feather mites, lice, or an environmental or nutritional factor, and that Often in these cases, there is evidence of growths or a scabby coating on the skin.

For one species there is a color test, and it is the most useful single sentence on this page. A bald Northern Cardinal's exposed head skin is normally black, and skin of a different color on the head indicates an ailment rather than a molt, according to Project FeederWatch. The source's own wording: Northern Cardinals have black skin, and a different color skin on the head of a bald-headed cardinal would indicate an ailment.

The parasite version has its own mechanism, and it stays on this side of the line rather than explaining the ordinary molt. Audubon describes mites whose feeding destroys the shafts of its feathers, left to work undisturbed on a bird's head because that is the one place preening cannot reach.

Nutrition and disease are raised as possibilities and left there: Some scientists consider poor nutrition and disease to be potential causes of baldness in birds, but no research has been conducted which conclusively confirms their suspicions.

Nobody knows why the head molt happens

The honest state of the question, stated by the project that collects the reports.

Project FeederWatch: No one knows for sure what causes baldness in birds, and the condition has not been well studied.

That sentence is worth quoting rather than smoothing over. The common answer, that it is a molt, describes what is happening to the feathers. It does not explain why the staggered sequence collapses in these birds, in these weeks, and mostly in first-year birds. Two organizations that see hundreds of these reports a year decline to say, and a confident explanation from anywhere else is worth treating accordingly.

Do bald birds grow their feathers back?

Yes, on a timescale of weeks, and both sources agree on the direction if not the precision.

FeederWatch: in most cases new head feathers grow in within a few weeks. Audubon is more specific: Downy feathers will appear within a week, and within two weeks the head feathers will have grown back completely.

FeederWatch also points to photographic evidence in its participant gallery: a bald Blue Jay, and the same bird four days later with feathers starting to grow in.

What should you do about it?

Very little, and one thing in particular to avoid.

Do not try to catch, handle, or treat a bald bird. A molting bird is going through a normal process on a schedule of its own, handling is stressful, and there is nothing a person can apply to a wild bird's head that improves on waiting. The recovery figures above happen without intervention.

The one action either source suggests is hedged, and the hedge should stay attached. Audubon: Because it is possible the baldness is caused by a nutritional deficiency, it can't hurt to provide nutritionally dense food in your feeders. The accompanying advice is about what not to offer: ornithologists recommend never feeding birds food that is low in nutrition, such as bread or crackers, which is the same conclusion reached at more length in what not to feed birds.

Where the skin looks wrong rather than merely bare, the response is not amateur diagnosis. It is the ordinary hygiene discipline: clean the feeder on a schedule, and if birds at your feeder are showing actual signs of illness, follow the guidance for a sick or dead bird at a feeder, which is a separate situation from a bald head.

Questions people ask

Why do birds go bald? Most reported cases are a late-summer molt in which the head feathers drop at once instead of in stages. A minority are attributed to feather mites, lice, or environmental and nutritional factors. Why the molt fails this way is not established: FeederWatch states that no one knows for sure and that the condition has not been well studied.

Why is my cardinal bald? Most likely the same simultaneous head molt, which FeederWatch says happens often enough in Northern Cardinals to fall within the normal range. Check the skin color: a cardinal's exposed skin is normally black, and a different color suggests an ailment.

Is a bald blue jay normal? For Blue Jays, FeederWatch describes this molt pattern as normal, and the birds are typically nearly bald for about a week.

Why do blue jays lose their head feathers and not other feathers? Because the head is the one area a bird cannot preen, and because in these cases the staggered molt that normally hides bare skin fails there.

Is a bald bird sick? Usually not, if the skin is otherwise clean. Growths or a scabby coating point to mites, lice, or another ailment rather than a molt.

Do bald birds grow their feathers back? Yes. FeederWatch reports new head feathers within a few weeks, and Audubon gives downy feathers within a week and full regrowth within two.

Should I help a bald bird? Do not catch or handle it. Audubon says only that offering nutritionally dense food cannot hurt, since a nutritional cause is possible but unconfirmed.

Why do birds go bald: the short version

A bald cardinal or Blue Jay in August is doing something the people who collect these reports call normal, or near enough to normal, and it will look like itself again within a couple of weeks. The head is where it shows because a staggered molt hides bare skin everywhere else, and because the head is the one place a bird cannot reach to preen.

What separates that from a problem is the skin underneath rather than the missing feathers: clean, and in a cardinal, black. Growths or scabbing is a different story, and it is a story for the feeder-cleaning routine rather than for a rescue attempt.

The sources volunteer the most useful caveat about themselves. Molt describes the mechanism, not the cause, and on the cause Project FeederWatch says plainly that nobody knows and that it has not been well studied. Anywhere you find a confident explanation of why these birds lose every head feather at once, it is going beyond what the people counting them are willing to claim.

This article contains no affiliate links and no photographs. The bald Blue Jay images described above belong to Project FeederWatch's participant gallery and are not reproduced here. Every claim is attributed to Project FeederWatch or to Audubon, which reports the account of FeederWatch's then Project Leader, Emma Greig.