Before leaving the subject of birds'-nests, I must say a few words about the immense number of birds which sometimes gather in one place for the purpose of raising their young. The enormous flocks of wild pigeons, which from time to time visit certain parts of the United States, have a definite portion of the woods, often several miles in extent, where they gather every night. This is called the "roost," and here they build their nests and rear their young. There are so many at these roosts that it is not always safe to go under the trees, for large branches are often broken off by the weight of the birds and their nests.
If you wish to know more about these pigeon-roosts, you will find long accounts of them in the books about birds, by those two celebrated men, Wilson and Audubon. Audubon's account of a roost which he visited in Kentucky is very interesting and well worth your reading. It is printed in the first volume of his "Ornithological Biography," and also, I believe, in the "Life of Audubon, the Naturalist."
In these books, and in the other works of Audubon and Wilson, you will also find much instructive and entertaining information in regard to all of our common birds. Most of our sea-birds are very wild, as they are much hunted by man, and on this account they build their nests and rear their young on inaccessible and uninhabited rocky islands, and the number of sea-birds which gather upon these islands during the breeding season is almost beyond belief; but the following account of Ailsa Craig, by Nathaniel P. Rodgers (the "Craig" is a rocky island on the west of Scotland), will give some idea of their abundance at such places:
It was a naked rock, rising nine hundred and eighty feet abruptly out of the sea. A little level space projected on one side, with a small house on it. We could not conjecture the use of a habitation there. The captain of the steamer said it was the governor's house. We asked him what a governor could do there.
"Take care of the birds," he replied.
"What sort of birds?" we asked him.
"Sea-fowl of all sorts," he said. "They inhabit the Craig, and ye'll may be see numbers of them. They are quite numerous, and people have been in the habit of firing to alarm the birds, to see them fly."
He ordered his boy to bring the musket. The boy returned, and said it had been left behind at Glasgow.
"Load up the swivel, then," said the captain; "it will be all the better. It will make quite a flight, ye'll find. Load her up pretty well."
The steamer meanwhile kept nearing the giant craig, which was a bare rock from summit to the sea. We saw caves in the sides of the mountain. We had got so near as to see the white birds flitting across the black entrances of the caverns like bees about a hive. With the spy-glass we could see them distinctly, and in very considerable numbers, and at length approached so that we could see them on the ledges all over the sides of the mountain.
We had passed the skirt of the Craig, and were within half a mile, or less, of its base. With the glass we could now see the entire mountain-side peopled with the sea-fowl, and could hear their whimpering, household cry, as they moved about, or nestled in domestic snugness on the ten thousand ledges. The air, too, about the precipices seemed to be alive with them. Still we had not the slightest conception of their frightful multitude. We got about against the center of the mountain when the swivel was fired, with a reverberation like the discharge of a hundred cannon, and what a sight followed! They rose up from that mountain—the countless millions and millions of sea-birds—in a universal, overwhelming cloud, that covered the whole heavens, and their cry was like the cry of an alarmed nation. Up they went,—millions upon millions,—ascending like the smoke of a furnace,—countless as the sands on the sea-shore,—awful, dreadful for multitude, as if the whole mountain were dissolving into life and light; and, with an unearthly kind of lament, took up their lines of flight in every direction off to sea! The sight startled the people on board the steamer, who had often witnessed it before, and for some minutes there ensued a general silence. For our own part, we were quite amazed and overawed at the spectacle. We had seen nothing like it before. We had never witnessed sublimity to be compared to that rising of sea-birds from Ailsa Craig. They were of countless varieties in kind and size, from the largest goose to the small marsh-bird, and of every conceivable variety of dismal note. Off they moved, in wild and alarmed rout, like a people going into exile; filling the air, far and wide, with their reproachful lament at the wanton cruelty which had driven them away.
This is only one of these breeding-places, but most of the rocky, inaccessible cliffs and uninhabited islands of the northern and southern shores of both continents are visited, at certain seasons, by sea-birds in equally great numbers.
No subject connected with the history of birds furnishes more interesting material for study than that of instinct. Young birds of different species show that they have very different degrees of instinctive knowledge. Some are able to take the entire care of themselves, and do not need a mother to watch over them; others, on the contrary, are perfectly helpless, and need teaching before they can do anything for themselves, except breathe, and swallow what is put into their mouths. The young chicken, a short time after it leaves the egg, knows how to take care of itself nearly as well as the young mound-bird. It can run after its mother, use its eyes, pick up food, and answer the call of the old hen; and it does all this without instruction. How different it is in all these respects from the young barn-swallow! This is blind, and unable to run, or even to stand, knowing only enough to open its mouth when it hears the old bird return to the nest, and to swallow the food placed in its open bill. Far from knowing by instinct how to use its wings, as the young chick does its legs, it does not learn this until it is well grown, and has had several lessons in flying; and even then it flies badly, and improves only after long practice. After it has learned to fly, it is still very helpless and baby-like, and very different from the active, bright-eyed, independent little chick of the barn-yard; and, indeed, the young of all the Rasores, or scratching birds, such as the hen, the quail, the partridge, the pheasant and the turkey. In the admirable picture of an English pheasant and its brood, on page 610, you will see how very much like young chicks the young pheasants are.
ENGLISH PHEASANT AND YOUNG.
The scratching birds are not the only ones which can take care of themselves at an early age. This is true of the running birds, such as the ostrich; and the same is the case with many of the wading birds, such as the woodcock; and among the swimming birds, there are several kinds that take full care of themselves soon after leaving the shell.
