"Adult male in breeding plumage.--Above black, mixed with chestnut or partly chestnut feathers on center of mantle; scapulars for the most part chestnut, but outer ones black at the ends or irregularly marked with black; accessory scapular plumes white; back and rump pure white; upper tail-coverts black, longer ones pure white; lesser wing-coverts blackish; innermost rather broadly edged with white, as also those near edge of wing; median coverts for the most part chestnut, slightly mottled with black; greater coverts blackish, narrowly margined and broadly tipped with white; alula and primary-coverts black, innermost of the latter with white tips; quills black with white shafts, and white bases to the inner primaries; secondaries for the most part white, blackish toward the ends of the feathers, these black markings decreasing gradually toward the inner secondaries, some of which are pure white, the innermost secondaries black, mottled with chestnut, like the scapulars; tail-feathers black with white bases, all but the center tail-feathers tipped with white, the black diminishing in size and forming a band toward the outer feathers, which are almost white; crown and hind neck white, the former streaked, the latter mottled with black; base of forehead and a narrow frontal line black, followed by a band of white, which unites with a broad eyebrow and is extended over ear-coverts; lores and fore part of cheeks white; feathers round eye and eyelid white, separated from the white loral patch by a narrow line of black, which unites the frontal band to a square, black patch beneath the eye, the latter joined to a malar line of black, which is connected with the sides of the neck and with the fore neck and sides of breast, all these parts being black, but nearly divided by a semi-lunar band of white, which reaches from the sides of the neck almost to the breast; throat and under surface of body from the center of chest downward, white; under wing-coverts and axillars pure white; quills below ashy whitish along the inner web. 'Bill black; feet deep orange-red, claws black; iris hazel.' (Audubon.) Length, 200; culmen, 23; wing, 157; tail, 58; tarsus, 24; middle toe with claw, 28. "Adult female in breeding plumage.--Much duller than the male, and having the same pattern of black and white about the face, but never developing the same amount of chestnut about the back, the head and hind neck being brown, mottled with blackish centers to the feathers. Length, 216; culmen, 23; wing, 160; tail, 62; tarsus, 24; middle toe with claw, 25.