I have not met with this species farther south than the Bay of New York. During the winter it is not rare about Boston and farther eastward. At the approach of summer, before the pairing of the Herring Gull, Larus argentatus, the White-winged Gulls collect in flocks, and set out for the distant north, where they breed.
The flight of this species so much resembles that of the Herring Gull, that were it not for its smaller size, and the different colour of its wings, it could not be distinguished from the other. It is less shy, however, proceeds farther up the rivers and salt-water creeks, and alights oftener on the water as well as on the salt-meadows, than that species. While at Portland in Maine, I observed a good number of these Gulls flying over the inner harbour close to the shores, descending towards the water, and picking up garbage in the manner of the Herring Gulls, with which they associated. Their notes were not so loud, nor so often heard.
I was surprised to find but very few on the coast of Labrador, and these did not seem to be breeding, for although we carefully watched them, we did not succeed in finding any nests.
LARUS LEUCOPTERUS, Bonap. Syn., p. 361.
LARUS LEUCOPTERUS, White-winged Silvery Gull, Swains. and Rich. F. Bor. Amer., vol. ii. p. 418.
WHITE-WINGED SILVERY GULL, Nutt. Man., vol. ii. p. 305.
WHITE-WINGED SILVERY GULL, Larus leucopterus, Aud. Orn. Biog., vol. iii.p. 553.
Adult, 26, 50.
During winter from New York to Nova Scotia. Not rare. Breeds on the islands and peninsulas of the Arctic Seas.
Bill shorter than the head, strong, nearly straight, compressed. Upper mandible with the dorsal line nearly straight at the base, arched and declinate towards the end, the ridge convex, the sides slightly convex, the edges sharp, nearly direct, the tip rather obtuse. Nasal groove rather long and narrow; nostrils in its fore part, lateral, longitudinal, linear, wider anteriorly, open and pervious. Lower mandible with a prominence at the end of the angle, which is long and narrow, the dorsal line then nearly straight and ascending, the sides flat and slightly inclined, the edges sharp and inflected.
Head rather large. Neck of moderate length. Body rather full. Wings very long. Feet of moderate length, rather slender; tibia bare below; tarsus somewhat compressed, covered before with numerous broad scutella, laterally and behind with roundish scales, on the outer side also with a row of small scutella; toes of moderate length, rather slender, all covered above with scutella; the anterior connected by reticulated webs, the two lateral with an external thick margin; the first extremely small, the third longest, the fourth longer than second; claw of hind toe smallest, of third largest, with an inner thin edge, of second next in size, all more or less compressed and obtuse.
The plumage in general is close, elastic, very soft and blended, on the back rather compact. Wings very long, broad, pointed; primaries tapering, the first longest, the second slightly shorter, the rest rapidly graduated; secondaries broad and rounded, the inner elongated and rather narrow. Tail of moderate length, even, of twelve broad feathers.
Bill gamboge-yellow, with a spot of orange-red near the end of lower mandible; the angle of the mouth and the edges of the eyelids are also orange-red. Iris pale yellow. Feet pale flesh-colour; claws greyish-brown. The whole plumage is pure white, excepting the back and upper surface of wings; the tips of the secondaries, the terminal third or so of the primaries, their shafts, and the upper tail-coverts also white.
Length to end of tail 26 inches, to end of wings 28 1/4; extent of wings 50; bill along the back 1 3/4, along the edges 2 1/2; tarsus 2 1/2; middle toe 2 1/12, its claw (4 1/2)/12; wing from flexure 17 1/2; tail 6 1/2.
Young in winter.
Bill yellow, the tips black. Edges of eyelids pale reddish-orange; iris brown. Feet yellowish flesh-colour; claws greyish-brown. The plumage is yellowish-grey, marked on the head and neck with longitudinal streaks of pale brown, on the back and wings with transverse undulations, those on the tail much fainter; the first six quills destitute of markings.