Did you ever think how well the bird is made to suit his life? Look at him.

To fit him to move through the air in flying, his shape is the same that men make their boats to move through water. It is sharp in front to cut his way as he goes through, for even the air needs to be cut.

It is narrower toward the back, and as he flies, the feet are drawn up or trail behind, and even the feathers lie backward. All this is so he can go swiftly through the air, and nothing, not even a feather, will hold him back.

To keep his body upright, so that he will not be top-heavy and tip over as he flies, his weight is mostly below the wings.

If we should try to go through the air as fast as a bird goes, we should find it very hard to breathe. But the bird is made for it. When you come to study his anatomy, you will see what a wonderful little creature he is.

He can sing while he is working very hard to fly upward. If you will try to sing while running up a hill, you will see how hard it is to do that.

A bird's head is joined to his neck at one place, something like a hinge. Other animals, like dogs and cats, have two hinges, or places of joining. That is why a bird is able to turn his head around so far that he can look down his own back. No other creature can do so.

Because of this, he is able to dress every feather on his body, and to sleep with his head laid back on his shoulder.

Nearly all birds have some of their bones hollow, and air-sacs, or pockets, under the skin. These sacs they can fill with air and make themselves light, so that those who live in the water cannot sink, but float like a cork.

Men who study the way birds are made do not yet know all the uses of the hollow bones and air-sacs. That is one of the things left for you young folk to find out.

Birds who get their food in marshes, or the edge of the water, have long legs for wading. They have also long necks, so they can pick up food from the ground.

Birds who swim have webs between the toes, that turn their feet into paddles.

Birds have very large gullets. In many cases the gullet leads into a place called the crop, where food is kept before it goes into the stomach. Sometimes the food is made soft in the crop, and then fed to the young ones, as I told you.

Birds have no teeth, yet they eat hard seeds, like acorns and grains of corn. To break these up, and get them ready for the stomach, they have a gizzard, which is a sort of grinding-mill. And to help in the work of grinding they swallow small stones.

One of the wonderful things about birds is the height at which they can live, and not only live, but fly. A man cannot go higher than twenty-two or twenty-three thousand feet, while moving about or exercising, because the air is so rare he cannot breathe. The highest a man was ever known to go and live, it is said, was less than thirty thousand feet, and that was in a balloon, where he did not move.

But birds go a good deal higher than this, and can fly—which is violent exercise—at that height. It is thought by some that the thinness of the air may be the cause of the great speed with which birds fly in that region. But there is still much to be found out about this.

Besides the marvels of flight, birds have other powers almost as strange. Many of them can fly under water with perfect ease, and, more than that, they can, when they wish, sink slowly till nothing is left above water but their beaks, to breathe. And they can stay so as long as they choose, keeping still in one spot, without moving.

A cormorant in a zoÖlogical garden, who wanted to catch some of the swallows skimming over the pond, sank his body till only his head was out, and held himself there perfectly still.

Birds who are hunted, as geese, have been known to save their lives in that way, by sinking their body under water, leaving in sight only the tip of the bill, which is so small it is not readily seen.

To do such things, birds must be able to make their bodies heavy when they choose, as well as light, which we know they are able to do by filling their air-sacs with air.

There are many things still to be found out about the powers of birds.