Adult male in breeding plumage.--Head, neck, tail, and under parts white; mantle and wing surface french-gray, with broad white tips to the scapulars and secondaries, making a conspicuous alar bar; all the primaries tipped with white; outermost quill blackish from the base downward (save a narrow gray wedge on inner web), with a white tip 63 mm. in length in mature birds, and a narrow, black bar which divides the white into tip and "mirror" in the majority; second quill blackish for about 10 mm. on both sides of shaft, with a black subterminal bar, a white mirror, and, on the inner web, a broad, gray wedge which sometimes breaks through and joins the mirror; third quill grayish basally, blackish on the lower part of outer web and on the subterminal bar, gray on the inner web, passing into white at the apex of the wedge; fourth similar but gray on both webs above the bar; fifth quill similar but bar narrower; sixth gray, without a bar in mature birds and with a narrow bar in others; the remaining quills gray with white tips. In less mature birds there is no mirror on the second quill. Ring around eye and gape bright orange-red; tarsi and toes pale flesh-color. Length, about 610; wing, 457; tail, 197; culmen, 74; tarsus, 70; middle toe with claw, 66. The female is smaller and less robust. Adult in winter.--Similar but head and neck streaked with ash-brown. Immature and young.--In the first autumn the upper parts are streaked and mottled with brown and grayish buff; quills dark umber, with paler inner webs and whitish tips to most; rectrices similar, but more or less mottled with whitish at bases of two or three outer pairs; feathers of upper tail-coverts brown, with buffish white tips; under parts nearly uniform brown at first, but afterwards brownish gray, mottled; bill blackish, paler at base of lower mandible. The second autumn the head is nearly white, streaked with grayish brown; the upper parts are barred with brown on a grayish ground, though no pure gray feathers have yet made their appearance on mantle; quills paler; tail more mottled with white at the bases of all the feathers. In the third autumn the feathers of the mantle are chiefly gray, with some brownish streaks down the shafts; a faint subapical spot begins to show on the outermost primary; the tail-coverts are partly white, and the dark portion of the rectrices is much broken up; under parts nearly white. In the fourth autumn the subapical patch on first primary is larger, and the quills from the fifth upward are banded with black and tipped with white; tail-feathers white, slightly vermiculated with brown; bill greenish yellow basally, reddish black at the angle. At the molt of the fifth autumn all brown markings are lost, the primaries have white tips, black bars, and gray wedges, though the proportion of dark coloring in quills is greater than it is in older birds. (Compiled from Saunders.)