What the bald cardinal in August is for

He comes to the feeder some morning in late August and you do not recognise him.

The body is the same brilliant red. The bill is the same coral pink. He cracks a sunflower seed in the same neat motion. But where the crest used to be there is now a small patch of dark grey skin, sometimes so blue-black he looks vaguely reptilian. The first time you see this you assume he is dying. The second time you see it, after Googling, you are told he is fine. By the third time, if you have stayed at the window long enough, you start to wonder what kind of bird arranges his own collapse on purpose every summer.

This is the bald cardinal of August. He is the most famous off-season phenomenon in North American backyard birding and the one most people who feed birds will eventually see. He is also, depending on how you look at him, a quiet demonstration of something most of us forget: that maintaining a body is work, that the work has costs the body pays in public, and that there are weeks of the year when the only honest thing to be is ugly.

Feathers cannot heal. Once a feather finishes growing it is dead tissue, as inert as a fingernail. The bird does not patch it. He does not condition it. He bathes, which removes dust and parasites, but he cannot mend the fray at the tip of a flight feather or the wear along the leading edge of a wing. So once a year, after the last brood fledges and before the cold sets in, the cardinal sheds the entire set and grows it back. The technical name is the prebasic moult. It runs six to twelve weeks. The bird looks scruffy throughout. He sings less. He stays closer to cover. By October he is whole again.

In most birds the moult is orderly. Pairs of flight feathers drop in sequence, body feathers turn over patch by patch, nobody notices. In a small percentage of cardinals, blue jays and grackles, something different happens. The head feathers all fall out at once, in a weekend, sometimes between Friday’s visit to the feeder and Monday’s. The leading explanation involves feather mites - a heavy infestation that the bird may dump in a single move - but the explanation is not settled. Cornell’s Project FeederWatch records “bald-headed bird” sightings every August and asks for photographs. The phenomenon is real, the geography is consistent, and the cause is still partly speculation. Birds will do this.

What is interesting is what the bird does not do. He does not hide. He keeps coming to the feeder. He cracks his sunflower seed with the same precision, defends his patch of holly, calls to his mate. He cannot fly as well as usual and he stays nearer cover than he did in May. But he does not stop. He has work to do and there is no version of being a male cardinal that does not involve being seen.

Behind the bald head, the body is doing something more interesting than the head’s collapse. The new feathers grow in dull. The brown tips on the wings, which will wear away over autumn to reveal the deep red beneath, are growing now. The carotenoid pigments that will make him the brightest cardinal you have ever seen in March, the pigments that the female cardinal will use, three months from now, to decide whether he is the right male to mate with again, are being routed into the feather barbs as he stands at your feeder looking like he has been pulled through a hedge backwards.

This is the part of the story I find quietly moving. A male cardinal in late August is preparing to be his most beautiful self next March, and he is preparing in the open, and the preparation looks rough. The shabbier he is in August the better-fed he has been in July, because the protein cost of growing all these new feathers is significant and a bird with reserves can afford the visible collapse. The dullest males in March are not the ones who looked roughest in August. They are the ones who skipped the deep moult because their bodies could not pay for it.

The carotenoids are not made by the bird. He absorbs them through his diet. Native autumn fruit - dogwood, sumac, hackberry, wild grape - is unusually rich in the carotenoid precursors that produce vivid red feathers. The brightest male cardinals at any feeder in March are the ones whose autumn yards had native fruit available. Female cardinals appear to know this. They choose mates partly on plumage brightness. A male’s August moult is, in this sense, his audition costume’s first fitting. By March the bird who looked worst this morning will be the one she picks.

People do not want to be told this. The bald cardinal arrives at our feeders looking unwell and we have a single response, which is concern. We Google. We worry about parasites. We consider taking the feeder down. The right response is the opposite. The bald bird is a healthy bird doing well-paid work in public. The wrong response is to treat him as a problem.

There is something to be said for noticing the difference. A pet bird molting in a cage is not a phenomenon. A wild cardinal molting in your hawthorn is a piece of the year. He returns every August like a clock you had not noticed was in the room. If you keep a feeder, you will see him. If you keep a feeder for a decade, you will see his sons.

What to do is almost nothing. Keep sunflower in the feeder. Keep the birdbath clean and full. If you have mealworms, scatter a few - molting birds want protein. Leave the dense cover alone. Do not try to catch him. Do not assume he is dying. By the third week of September his crest will be back and the wings will be tighter than they have been all year. He will look, briefly, brand new. By October he will look like the bird you photograph against the first snow.

The thing the bald cardinal is doing for himself in August is what makes him worth photographing in February. The investment is in private even when it is in plain sight. Almost nothing in nature works quietly. Most of the bird’s most important hour is the one he spends, in late summer, looking like the worst version of himself at someone else’s window.