At the beginning of the first autumn, the plumage of the young so much resembles that of the young of Sterna Hirundo, that a person, not paying attention to the tarsi and feet, might readily confound them together. Yet even at this early age, there are strong indications of the bluish tint on the under parts. The longest tail-feathers at this period do not extend more than two inches beyond the rest; the upper parts of the body are mottled with brown, as in all the other species, and in Gulls. The mantle of this, as of all other Terns, assumes its permanent hue before any part of the wings. On the 5th of August, in Labrador, the young birds were gambolling along with their parents, over the shores of Bras d’Or Harbour, and when we left that country the Terns still remained, so that I am unable to state at what particular period they commence their journey southward.
The notes of this species resemble the syllables creek, creek, and are often repeated while the bird is on wing. During autumn it follows the sinuosities of the shores of the bays and inlets, ascending against the ebb, and, returning to meet the tide, which enables it to procure its food in succession while it keeps on its course. I have only farther to mention a curious fact, which is, that all the Terns which breed in the northern parts of the United States, and in regions still nearer the pole, sit closely on their eggs, while the small species that breed to the southward incubate only during night, or in rainy weather.
Sterna arctica, Temm. Man. d’Ornith. part ii. p. 742.—Ch. Bonaparte, Synops. of Birds of the United States, p. 354.—Swains. and Richards. Fauna Bor. Amer. part ii. p. 414.
Arctic Tern, Nuttall, Manual, vol. ii. p. 275.
Adult Male in Spring. Plate CCL.
Bill about the same length as the head, slender, tapering, compressed, nearly straight, very acute. Upper mandible with the dorsal line slightly arched, the ridge rather broad and convex at the base, narrow towards the end, the sides convex, the edges sharp and inflected, the tip acute. Nasal groove extended beyond the nostrils nearly to the tip; nostrils basal, linear, direct, pervious. Lower mandible with the angle extremely narrow, very acute, extending beyond the middle, the dorsal line straight, the sides erect and slightly convex, the sharp edges inflected, the tip extremely acute.
Head of moderate size, oblong; neck of moderate length; body very slender. Feet very small; tibia bare for a considerable space; tarsus extremely short, slender, roundish, covered anteriorly with small scutella, laterally and behind with reticular scales; toes very small, slender, the first extremely small, the third longest, the fourth nearly as long, the second much shorter, all scutellate above, the anterior connected by reticulated webs having a concave margin; claws arched, compressed, acute, that of hind toe smallest, of middle toe by much the largest, and having the inner edge thin and dilated.
Plumage soft, close, blended, very short on the fore part of the head; the feathers in general broad and rounded. Wings very long, narrow and pointed; primary quills tapering, slightly curved inwards, the first longest, the rest rapidly graduated; secondary short, broad, incurved, rounded, the inner more tapering. Tail long, very deeply forked, of twelve feathers, of which the outer are tapering, the middle short and rounded.
Bill, mouth, and feet vermilion tinged with carmine. Iris brown. The upper part of the head and elongated occipital feathers greenish-black; the sides of the head and chin white; the upper parts pale greyish-blue, the rump lighter, the tail white, excepting the outer webs of the two lateral feathers which are dusky grey, primaries dusky towards the ends, the two outer with their outer webs blackish, all with the greater part of the inner web white; secondaries tipped with white. Neck, breast and sides pale greyish-blue, like the upper parts, but lighter; abdomen, under tail-coverts, and lower surfaces of wings and tail white.
Length to end of tail 15 1/2 inches, to end of wings 13 1/2, to end of claws 9 3/4; extent of wings 32; wing from flexure 10 1/2; tail to end of shortest feathers 3 1/4, to end of longest 7 1/2; bill along the ridge 1 1/4, along the edge of lower mandible 1 10/12; tarsus 8/12; middle toe 8 1/2/12, its claw 2 1/2/12. Weight 2 3/4 oz.