Part 20

Feathers of all kinds are made in the same way. All have, first, a quill, the horny part next to the body; second, a shaft, the white part on which the barbs grow; third, the barbs, which grow out on each side of the shaft, and together are called the vane; fourth, the barbules, or little barbs, growing out of the barbs; and last, the barbicels, which grow on the barbules, and on the wings have the tiny hooks which hold them together.

But though feathers are made on the same pattern, they look very different. The wing and tail feathers are stiff and strong, and are called flight feathers, but those on the breast and body are called soft, and cling closely to keep the bird warm and dry. These are called the clothing feathers, because they clothe the bird.

Down feathers, which are almost always hidden under the clothing feathers, are, like their name, downy, and answer to our under-clothes.

Thread feathers grow among the clothing feathers, and are almost like hairs. It is these that the cook singes off the fowls.

Kingfishers who dive, and ducks who spend much time on the water, have very thick down under the feathers--like suits of very warm under-clothes--which keeps the water away from their bodies. Thus they can dive, or sit on the water hours at a time, and not feel wet at all.

Powder-down feathers grow on some herons and cockatoos. They are called by that name because the tip ends are continually breaking off like white dust. Nobody knows their use.

Different from all these are the feathers called plumes, like the long, soft ostrich plumes we all know; the dainty little ones that stand straight up, and look as if the wind would blow them away; the long, showy feathers that the peacock spreads with so much pride, or even the pretty, drooping ones in the cock's tail.

These feathers are of no use for flight or for warmth, they rather hinder than help. They are for ornament, and there are many kinds among birds, all exquisitely beautiful. Nature has given to birds a more wonderful dress than to any other living creature.

It is with his feathers that a bird expresses his feelings. In anger he fluffs them out till he looks twice as big as usual; we have all seen a hen bristle up when a dog comes near her brood.

Nervousness or excitement is shown by jerking the wings and tail, and if a bird wishes to escape notice, he can make his plumage a perfect disguise. Mr. Bolles's pet owl would stretch himself up long and slim, with feathers hugging his body, when he looked so much like a broken branch of a tree that Mr. Bolles could hardly see him. And another owl that I heard of, when he was on the ground, would flatten himself and spread his plumage around, so that the eye could scarcely separate him from the dead leaves about him.

No one takes better care of his dress than a bird, and that is why it looks well for a year. Every day, with most birds, it is washed and carefully dried, each feather being passed through the bill, and the whole thoroughly shaken out. At night one may often see robins and catbirds before going to bed, dressing their plumage and shaking off the day's dust.

Besides washing and drying the feathers, birds need oil to keep them in best condition. For this purpose they have a little "oil jug," a small gland over the tail, out of which, with the bill, they can squeeze a drop of oil. We often see ducks and geese oiling their feathers before a rain.

Water birds, who need a great deal of oil to keep out the wet, have the oil jug very large.

Birds seem to know perfectly well the beauty of their plumage. Not only do they try to show it off, as the peacock when he spreads his tail, but they seem to feel shame when their feathers are injured or soiled. One white feather coming in where it does not belong will make a bird very unhappy. He will work and tug at it to pull it out, and often make himself actually ill over the trouble. I had a captive bird who died, I think, from worry and work over a wing feather which persisted in coming in white, and which he insisted on pulling out every time.

XXVII

DIFFERENT COLORED SUITS

A BIRD does not always wear the same colored dress, as I said in the chapter on moulting. A goldfinch, who through the summer wears a gay yellow coat, comes out in the fall in plain olive and black; and the scarlet tanager, who flourishes in the most brilliant red, changes to a quiet green in winter. Besides these, some birds wear at one season a spotted coat, and come out afterwards in one of plain colors.

Most of them change by moulting, as I explained, the old feathers dropping out and new ones of another color coming in; or, to speak exactly, the new ones growing out and pushing the old ones off on their tips. But some change color without moulting. All birds moult completely in the autumn, many moult partially in the spring, and some, as I said, change without moulting.

This last change of color is made partly by fading, and partly by breaking off the tips of the feathers, or what is called "abrasion." This is a curious process. I told you something about it in chapter vii. Certain feathers have edges different in color from the rest; as, for example, a black feather with tips of yellow. While the feathers are new and perfect, as they lie over each other like shingles on a roof, only the edges show, and these being yellow, the bird appears to be dressed in yellow. But the yellow tips are not so strong as the rest, and they break or wear off, or are pulled off in the spring. What is strange, they break exactly where the black begins. So as soon as the yellow is off, the black shows, and behold, the yellow bird suddenly becomes a black bird.

That is the way some birds manage to put on their spring dress in the fall. The solid color is the color of the spring, but it is hidden or veiled by tips of another color for winter.

The meadowlark changes in this way. In the winter his coat is brownish, or buff. In the spring these tips are worn or broken off, and he comes out in yellow and black.

Another change, even more curious, is made by some birds, who all winter wear white spots, or light scolloped edges to their feathers, and in spring the spots are gone.

In these, the white or light parts only break off, as sharply as if cut with scissors. They leave the edges of the feathers notched in queer ways, but as they lie over each other that does not show.

Birds in this way can change color without changing their feathers. While moulting but once a year, they can show two suits, and by partially moulting twice, can show three suits.

Another thing about the color of feathers is interesting. Some colors, such as black, and red, and brown, are caused by coloring matter in the feather. But other colors are only an effect of the way the feather is made, whether it has ridges on it, or certain minute specks under the surface, which seem to act as prisms (says Dr. Newton), and reflect the light in different colors.

For instance, green is always due to some shade of yellow coloring matter under a surface full of lengthwise ridges, and other colors are made in similar ways.

These curious facts have been found out by that tell-tale little instrument the microscope, and no doubt it will reveal many more secrets in time.

Color is useful to birds, as well as beautiful. Its great use is to conceal them from their enemies, and they show that they know this by their conduct.