VII. Raptores.
Rapacious birds, with strong, curved, pointed, and sharp-edged beak; legs short and robust, three toes before and one behind, armed with strong, crooked talons. The order includes—
I. Nocturnes, Owls.
II. Diurnes, Eagles, Vultures, Hawks.
CHAPTER I.
THE NATATORES, OR SWIMMING BIRDS.
The Natatores are obviously devoted, by their organisation, to an aquatic life. Their constant haunts are found on the great rivers and lakes, or on the coast. They are chiefly characterised by the form of their feet. The toes are united by marginal membranes in the Coots and Water-rails, or in others by the extension of webs between and uniting the toes, of a soft membrane slightly lobed; hence the name of Palmipedes, or web-footed, usually applied to them. These broad palmate feet, acting at the end of a long lever, strike the water with great force when fully expanded, being favoured by their backward position. When the bird recovers its stroke, the toes are relaxed in their forward movement, preparatory to another effort; thus progression through the water is obtained.
Some of the swimming birds in their flight are feeble and slow; others are incapable of even rising from the water, being only furnished with rudimentary wings. Again, there are species which possess extraordinary powers of traversing the air, their well-developed wings enabling them to pass through space with wonderful rapidity. The Albatross is met with on the high seas at a vast distance from the shore. Others, as the Petrels, seem to revel in storms and tempests, mingling their wild cry with that of the storm-tossed waves. The sailors, who look anxiously to windward at the dark horizon, where the clouds are surcharged with torrents of rain ready to burst on the ship, are assured of the approaching tempest by the circling flight of the white-winged Albatross, as it is seen through the obscure and threatening mist.
The whole order of Natatores swim and dive without saturation, their plumage being anointed by an oily liquid furnished by certain glands in their skin, which renders them impervious to moisture. This immunity from the effect of water is further assisted by the disposition and structure of their feathers, which, being smooth and three-cornered, with the barbules closely interlaced, cause the water to glide off their polished surface; while the down beneath the feathers of which we have spoken protects their bodies from the cold, maintaining their natural heat, and enabling them to resist the cold of the most rigorous winter.
The Natatores are numerous both in species and individuals, having their habitat in all countries. According to Prince Charles Bonaparte, one of the most eminent of European naturalists, those which frequent the sea-shore alone constitute one-fourteenth part of all the birds on the globe, and the number of species he reckons at nine thousand four hundred. They feed on vegetables, insects, mollusks, and fishes. They seek the coast in the breeding season, where they build their nests on the sand, or in nooks and crannies of the rocks, or on the margin of lakes and rivers.
In the spring the sea-birds assemble in large flocks, pair off, and proceed to deposit their eggs in nests constructed generally without skill, but always lined or carpeted with a fine down, which forms a soft warm bed for the embryo progeny. Certain localities are frequented by preference, which are occupied by innumerable flocks in the breeding season, all of which seem to live together in perfect harmony. Some of the families of the Natatores are valuable additions to the poultry-yard. Ducks and Geese furnish delicate and nourishing food for man; the Swan is gracefully ornamental on our lakes and ponds. The down of all the aquatic birds is of immense value to the commerce of northern countries. The eggs are good to eat, and in many countries the inhabitants consume them in great quantities. Nor does their usefulness end here. Guano, so eagerly sought for by the farmer, is the excrement of aquatic fowls—the accumulation of ages, until, in the South Pacific Ocean, it has formed whole islands, some of them being covered with this valuable agricultural assistant to the depth of ninety or a hundred yards. Nor is this so marvellous, if it is considered that twenty-five or thirty thousand sea-birds sleep in these islets night after night, and that each of them will yield half a pound of guano daily. Our lands receive valuable assistance to fertility from this unrivalled material, which owes its power to the ammoniacal salts, phosphate of lime, and fragments of feathers of which it is composed.