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Family II. COLYMBIDÆ.
(Divers.) Much more exclusively aquatic than the Ducks, the Family before us, as their name imports, are remarkable for the readiness and frequency with which they descend beneath the surface of the water, and for the great length of time during which they can remain immersed. They have the beak narrow, straight, and sharp pointed; the head small; the wings short and hollow; the legs, placed very far behind, near the extremity of the body, are flattened sidewise so as to present a thin edge before and behind ; the toes armed with broad flat nails. In one genus the toes are united by a membrane, and there is a short tail; in the other two the toes are divided midway to the base, but are margined with broad oval membranes, and there is no vestige of a tail. The latter chiefly affect fresh waters, the former reside upon the ocean.
The backward position of the feet in these birds, while it renders them powerful and fleet swimmers and divers, greatly diminishes their ability for walking. Indeed they scarcely walk at all, for though they can shuffle along awkwardly in an erect position, it is only for a few steps, when they fall down upon their breast, or else remain sitting erect, supported upon their broad feet as a base, the whole tarsus resting on the ground. Their powers of flight are nearly as limited : but under the surface of the water the wings are expanded and used effectually as fins. The plumage is filamentous or downy, but yet remarkably dense and close lying, and has a silvery or satiny gloss, particularly on the under parts of the body.
The food of the Divers consists, according to their size and the situations they frequent, of fishes with their fry and spawn, crustacea, waterinsects, tadpoles, and perhaps vegetable substances occasionally. Their geographical distribution is extensive, though the number of known species is small; the Grebes are widely scattered over the fresh waters of the globe, but the Loons are confined to the temperate and arctic oceans and their coasts.
GENUS COLYMBUS. (LINN.) In the Loons or true Divers, the beak is long, strong, straight, compressed, and pointed; the edges cutting, but not notched: the nostrils, on each side of the base, are perforated, and partly closed by a membrane. The legs are thin, the tarsi compressed, placed far back, and closely attached to the ħinder part of the body; the feet large, amply webbed, the outer toe longest: the hind toe jointed upon the tarsus, small; the wings short, the first quill-feather longest; the tail short and rounded.
The habits of these birds are peculiarly marine; they are at home amidst the desolation of the polar seas, on whose wild and frost-bound shores and islands they rear their young, laying their eggs on the bare ground. The general colours of their plumage are black and white, the latter arranged in beautifully regular rows of spots, which are commonly lost in winter.
The largest and finest species is that called the Great Northern Diver, or Loon (Colymbus glacialis, Linn.), a frequent visitor to our coasts. It is larger than a Goose, its head and neck are black, glossed with purple or green; the upper parts of the body and wings black, regularly
marked with spots of white set in rows, large and square on the scapulars, elsewhere small and round. Two bands going partly round the neck and the upper breast are white, with each feather marked with black down the shaft: the under parts are pure white.
The Divers live chiefly at sea, except during the breeding season, and obtain their living by following the shoals of fishes which approach the shallows to spawn, especially the herrings, sprats, &c. These they catch with great ease and certainty by diving, pursuing their prey with swiftness beneath the surface. Dr. Richardson found the Northern Diver more abundant on the interior lakes of Arctic America than in the ocean ; he says it destroys vast quantities of fish. " It takes wing with difficulty, flies heavily, though swiftly, and frequently in a circle round those who intrude on its haunts. Its loud and very melancholy cry, like the howling of the wolf, and at times like the distant scream of a man in distress, is said to portend rain. Its flesh is dark, tough, and unpalatable.”
The following interesting account of the manners of this species in captivity is given by Mr. Nuttall of Boston.
“A young bird of this species which I obtained in the Salt Marsh at Chelsea Beach, and transferred to a fish-pond, made a good deal of plaint, and would sometimes wander out of his more natural element, and hide and bask in the grass. On these occasions he lay very still, until nearly approached, and then slid into the pond, and uttered his usual plaint. When out at a distance he made the same cautious efforts to hide, and would commonly defend himself in great anger, by darting at the intruder, and striking powerfully with his dagger-like bill. This bird, with a pink-coloured iris, like albinos, appeared to suffer from the glare of broad daylight, and was inclined to hide from its effects, but became very active towards the dusk of the evening. The pupil of the eye in this individual, like that of nocturnal animals, appeared indeed dilatable; and the one in question often put down his head and eyes into the water to observe the situation of his prey. This bird was a most expert and indefatigable diver, and remained down sometimes for several minutes, often swimming under water, and, as it were, flying with the velocity of an arrow in the air. Though at length inclining to become docile, and shewing no alarm when visited, it constantly betrayed its wandering habits, and every night was found to have waddled to some hiding-place, where it seemed to prefer hunger to the loss of liberty, and never could be restrained from exercising its instinct to move onward to some secure or more suitable asylum.”*
The eggs are two in number, sometimes three, of a dark olive hue, with a few spots of brown; they are about as large as those of a goose.
Family III. ALCADÆ.
(Auks.) The haunts and habits of these singular birds are exclusively maritime; they are oceanic birds formed for diving, living on small fishes obtained in this manner, and on marine crustacea and mollusca. In the Loons we saw the feet removed to the extremity of the body, but these organs were still ample, and were used in the act of diving; in the Auks the tarsi are very short and the feet small; and in progression under water no use whatever is made of the feet, which are
* Quoted in Yarrell's Brit. Birds, iii. 427.