For the Birds Radio Program: Bathing
How do birds keep their feathers clean and supple?
(Recording of a American Bittern)
The one truly unique characteristic of birds is their feathers, which feature prominently not only on the birds themselves but also in literature, from the birds of a feather that flock together through people who wear a feather in their caps as they feather their nests. But to keep these fine feathers in fine fettle, birds can hardly use a feather duster, so they’ve have developed many interesting ways of maintaining their plumage.
Water baths are probably the most obvious way of cleaning feathers. In back yards birds can bathe in birdbaths and under lawn sprinklers. In the wild they take their baths wherever they find shallow water–in little pools at the edge of streams and rivers, in ponds and puddles, even in water collected in rotten tree stumps. Swifts and swallows skim the water’s surface on the wing–a time study man’s dream. But most songbirds sit in water one to three inches deep to bathe. They start their bath by ducking their head in and out, making water run down their neck and back. Then they flutter their wings, allowing water to run among all their feathers. When standing water isn’t available, many birds wet their feathers on dew- or rain-covered leaves or grass.
Wet birds look pretty disgusting–bedraggled and scrawny with the feathers plastered flat against them. And saturated feathers become compacted and heavy, making it difficult or even impossible to fly. So after bathing, birds quickly head for cover on a secluded perch to preen. Bird baths should always be set near shrubbery or trees so that bathing birds can quickly get away if a cat or hawk appears.
Water bathing itself probably doesn’t wash away much dirt– the real benefit comes from preening afterwards. Nibbling on the wet feathers and drawing them through the beak removes dirt and parasites, and realigns the barbs, making the feathers smooth again. Also, preening birds frequently rub their beaks on an oil gland just above the tail. The oil acts as a conditioner on the feathers, beak, and feet, plus it has a chemical precurser to vitamin D in it, which sunlight converts to usable vitamin D.
Many birds don’t take water baths at all–it seems they were the original inventors of dry cleaning. Some of them, including some pheasants and grouse, never bathe in water. Like Charles Schulz’s Pigpen, they engulf themselves in the dust of ancient civilizations. House Sparrows bathe in dust, too, though they also take water baths. Sifting dust through their feathers improves the alignment of the barbs, blots out oils and moisture, and probably controls dandruff and mites. It also fluffs out the feathers, filling the spaces with air which improves insulation.
Some birds have unique cleaning problems because of their diets. Vultures, which scavenge on decayed meat, don’t have any feathers on their heads at all. By simply dipping their bald heads in water they can clean off much more easily than they could clean goopy feathers. Bitterns, herons, and some other fish-eaters have special powder down feathers. After swallowing a fish or two, their head and neck feathers get gunked up with fish slime. These birds can rub the mucky parts on their powder down patches to blot the muck. Then they can easily scratch off the powdered slime with their claws, which pretty much explains why the science of studying fish is called “ick”thyology.
(Recording of a American Bittern)
This is Laura Erickson, and this program has been “For the Birds.”