The young are at first covered with black down. When fledged they are olivaceous on the upper parts, dull purple beneath; the bill dull green. After the first moult, the bill is light carmine, greenish-yellow at the end, the head dark purple; the plumage coloured as above described, but less brilliant, the tarsi and toes greenish-yellow.
In a male bird, the tongue is 10 twelfths of an inch long, sagittate at the base, with conical papillæ, of which the outer are larger, slightly concave above, horny towards the end, which is thin, rather obtuse, and lacerated. On the middle line of the roof of the mouth anteriorly is a row of large blunt papillæ, behind which are two rows; aperture of posterior nares linear. Œsophagus 7 inches long, of moderate width, its greatest diameter, at the lower part of the neck, where it is a little dilated, 8 twelfths. Proventriculus 1 2/12 long; its glandules 1 1/4/12 long. Stomach a large and powerful gizzard, broadly elliptical, 1 1/2 inch long, 1 5/12 broad, its lateral muscles large, the tendons covering nearly their whole surface, the left muscles 1/4 inch think, the right 5/12, the cuticular lining moderately rugous. Intestine 21 inches long, from 5/12 to 3/12 in diameter. Rectum 2 3/4 inches; cæca 2, their diameter 3/12 towards the end.
Trachea, moderately extended, 5 1/2 inches long, its greatest breadth 3 1/4/12, its least 1 1/2/12. Its rings 130, very slender, unossified, collapsed, and owing to their narrowness in the middle line before and behind, seeming as if broken there; bronchi with 15 half-rings. The contractor muscles moderate, the sterno-tracheal slender; a pair of muscles on the lower larynx, from the lower rings of the trachea to the membrane over the first bronchial ring.
In the mouth was a small frog, in the pharynx two, in the œsophagus two more, a large piece of root, numerous fragments of insects, and a leach, the frogs 2 1/2 inches long. In the gizzard were seeds, and fragments of white fleshy roots.
GREAT NORTHERN DIVER OR LOON.
Colymbus glacialis, Linn.
PLATE CCCVI. Adult Male and Young Male.
The Loon, as this interesting species of Diver is generally called in the United States, is a strong, active, and vigilant bird. When it has acquired its perfect plumage, which is not altered in colour at any successive moult, it is really a beautiful creature; and the student of Nature who has opportunities of observing its habits, cannot fail to derive much pleasure from watching it as it pursues its avocations. View it as it buoyantly swims over the heaving billows of the Atlantic, or as it glides along deeply immersed, when apprehensive of danger, on the placid lake, on the grassy islet of which its nest is placed; calculate, if you can, the speed of its flight, as it shoots across the sky; mark the many plunges it performs in quest of its finny food, or in eluding its enemies; list to the loud and plaintive notes which it issues, either to announce its safety to its mate, or to invite some traveller of its race to alight, and find repose and food; follow the anxious and careful mother-bird, as she leads about her precious charge; and you will not count your labour lost, for you will have watched the ways of one of the wondrous creations of unlimited Power and unerring Wisdom. You will find pleasure too in admiring the glossy tints of its head and neck, and the singular regularity of the unnumbered spots by which its dusky back and wings are checkered.
I have met with the Great Diver, in winter, on all the water-courses of the United States, whence, however, it departs when the cold becomes extreme, and the surface is converted into an impenetrable sheet of ice. I have seen it also along the whole of our Atlantic coast, from Maine to the extremity of Florida, and from thence to the mouths of the Mississippi, and the shores of Texas, about Galveston Island, where some individuals in the plumage characteristic of the second moult, were observed in the course of my late expedition, in the month of April 1837. Indeed, as is the case with most other species of migrating birds, the young remove farther south that the old individuals, which are better able to withstand the cold and tempests of the wintry season.
The migratory movements of this bird seem to be differently managed in the spring and autumn. In the latter case, a great number of young Loons are seen to alight on the head waters of our great streams, on which, without much exertion, being aided by the current, they float along, diving at intervals in pursuit of the numerous fishes, as they proceed toward milder climes. The few old birds which, at a later date, appear on the same water-courses, frequently take to wing, and shorten their way by flying at a considerable elevation directly across the great bends or peninsulas. These modes of travelling are also adopted by those which advance along the Atlantic coasts, where, indeed, the birds have the double advantage of meeting with food and obtaining repose, on the rivers and on the sea. I think, however, that this maritime course is followed only by such of the Loons as have bred in the more immediate vicinity of the coast. But whether you are in the interior, or on the coast, it is seldom that you see at a time more than one Loon travelling at this season; whereas, in spring, they proceed in pairs, the male taking the lead, as is easily ascertained by observing that the bird in the rear is the smallest.
Although, its wings are rather small, its flight is strong and rapid, so that it is enabled to traverse a large extent of country on wing. When travelling, or even when only raised from its nest, it moves through the air with all the swiftness of the other species of its tribe, generally passing directly from one point to another, however distant it may be. Its long transits are at times performed at so great an elevation, that its form can scarcely be distinguished, and yet, even then, in calm weather, the noise of its wings striking the air comes distinctly on your ear. I have seen them thus, on their way towards Labrador, passing over the head waters of the Bay of Fundy, to cross the Gulf of St Lawrence. Whenever it chances to alight on the water, in the course of its long journeys, it almost immediately dives, as if to taste the water, and judge whether it contains food suited to its appetite. On emerging, and after having somewhat raised the fore part of its body, shaken its wings, and by a strong shiver rearranged its plumage, it emits its loud echoing call-note, to induce, perchance, some traveller of its tribe to alight for awhile, that they may communicate to each other their experience of the past, or their hopes of the future. There is an absurd notion, entertained by persons unacquainted with the nature of this bird, that its plaintive cries are a sure indication of violent storms. Sailors, in particular, are ever apt to consider these call-notes as portentous. In the course of a voyage from Charleston to the Florida Keys, in May 1832, I several times saw and heard Loons travelling eastward; but, notwithstanding all the dire forebodings of the crew, who believed that a hurricane was at hand, our passage was exceedingly pleasant. Although I have heard the notes of the Loon in rainy and blowy weather, yet I never heard them so frequent or so loud, both by day and by night, as on the Ohio, during that delightful and peculiarly American autumnal season called the Indian Summer; when, although not so much as a cloud was seen for weeks, I have frequently observed the passing birds checking their flight, or heard the murmuring plash which they produced on alighting upon the placid water, to rest and refresh themselves.