"Adult male in winter plumage.--Above light ashy gray, somewhat paler on the edges of the feathers, which have dusky brown centers; lower back, rump, and upper tail-coverts blackish, with slight remains of sandy-buff fringes; sides of rump and lateral upper tail-coverts white; wing-coverts rather darker than the back, marginal ones dark brown; median series blackish in the center with hoary white margins; greater series dusky blackish edged with hoary gray, inclined to white at the ends, and forming a narrow band across wing; alula and primary-coverts black tipped with white, the latter broadly; quills black, paler brown on inner webs of primaries, excepting at tips, which are black; secondaries merely fringed with white near the ends, and with a little white towards base of inner web; inner secondaries ashy like back; shafts of all the quills white or whity-brown; middle tail-feathers blackish like upper tail-coverts, the others ashy brown with white shafts and white fringes; crown like the back; lores dusky, surmounted by a broad white streak, which is continued into a narrow eyebrow; sides of face white, with only a few tiny streaks of dusky brown; ear-coverts uniform dusky brown; under surface white, with a few streaks of dusky brown on lower throat and sides of breast; under wing-coverts and axillars white, the marginal coverts mottled with dusky bases, lower primary-coverts ashy. Bill dusky black; legs and feet slaty black; iris dark brown. Length, 165; culmen, 33; wing, 104; tail, 41; tarsus, 20. "Adult male in breeding plumage.--Above black, slightly varied with rufous edgings to the feathers, some of those of mantle, scapulars, inner greater coverts, and inner secondaries having sandy-buff margins, the black forming large subterminal spots; crown black, with a sandy-buff lateral stripe; lores black; sides of face rufescent, thickly spotted with dusky black like sides of neck; ear-coverts rufous, and surmounted by a pale buff eyebrow, which becomes lighter above the lores; chin and under surface of body white; throat, fore neck, and chest thickly spotted with dusky blackish, the spots on the fore neck and chest somewhat arrow-shaped, as they are also along the sides of body, all these parts slightly tinged with rufous; lateral upper tail-coverts barred with black; tail-feathers as in the winter plumage, but with a more extensive area on the inner webs. Length, 165; culmen, 30; wing, 105; tail, 38; tarsus, 20. "Adult female in breeding plumage.--Similar to the male, but not quite so plentifully spotted underneath.