Body care

All birds have feathers, and this common feature requires that they spend much of their time maintaining their plumage. Birds have surprisingly similar ways of bathing, oiling, and preening their feathers.

Preening is the behaviour in which a bird slides its beak over individual feathers in such a way that it connects the individual barbules (hooks) of the feather vanes together. Small birds, such as sparrows, may have 2.000 feathers, while larger birds, such as swans, may have as many as 25.000 feathers. Most feathers have a central shaft (rachis) and a wide region on either side called a vane. Preening restores separated barbules in the feather vane and helps the bird to maintain the feather surface.

Oiling is the feather-maintenance behaviour in which birds squeeze their uropygial (oil) gland to lubricate their feathers. This gland is located on the rump, just above the base of the tail. By squeezing and rubbing the beak sideways over the gland, a bird can use its beak to obtain oil and spread it onto the feathers while preening. This oil lubricates the tiny feather barbules and extends their life by helping to keep them from becoming too brittle. Well-lubricated and preened feathers also help to shed water and give the birds a waterproofed plumage. Water sheds off a duck’s back (and even a sparrow’s back) mainly because the feather barbules are so neatly connected that water does not have a chance to soak into the plumage. In some species the oil contains ergosterol, which converts into vitamin D when exposed to sunlight. When swallowed, the vitamin D helps prevent such diseases as rickets.

Bathing in water helps to clean the plumage. Some seabirds, such as terns, bathe on the surface of the ocean; others, like gulls, often fly to freshwater ponds and lakes for bathing. Robins and grackles bathe in the water that collects on large leaves. Where standing water is not available, cold-climate birds may bathe in snow, while hawks and vultures just spread their wings in the rain.

Regardless of a bird’s size, the bathing behaviour is similar. Birds typically first submerge their head, then quickly raise it and beat their wings in the water. This is usually followed by vigorous shaking, feather fluffing, preening, and oiling. Birdbaths are an excellent way to attract birds into your yard. Many species that do not readily come to feeders, such as catbirds and even screech-owls, will use birdbaths.

Dustingis most common among birds that live in dry, open habitats. House Sparrows, Ruffed Grouse, Wild Turkeys, wrens, kinglets frequently dust bathe. House Sparrows seem to enjoy company as they dust bathe. Sometimes a dozen or more will gather, each scooping out a body-sized patch of dust in which it vigorously flutters its wings and spreads its tail while pressing its breast deep into the dust. While lying in the dust, they frequently peck and scratch with their feet. After dusting, the birds typically give their plumage several vigorous shakes to remove excess dust and then scratch their head and preen their feathers. Dusting probably helps to eliminate such parasites as feather lice and mites. Dusting may also function to remove excess oil, dandruff, and moisture that might otherwise cause feather matting. Most birds that bathe in dust usually do not take water baths.

<== попередня сторінка	\|	наступна сторінка ==>
Master builders	\|	Summary

Не знайшли потрібну інформацію? Скористайтесь пошуком google:

Генерація сторінки за: 0.023 сек.