- Medium-sized to large shorebird.
- Legs moderately long.
- Neck short.
- Bill short.
- Head large and rounded.
- Gray and black on back.
- In breeding plumage, black from face to belly.
- Rump white.
- Large black spot in armpits.
Male DescriptionBreeding male with vivid white stripe on either side of neck running from front of crown to wing. Crown pale gray, in palest individuals scarcely distinct from neck stripe, with scattered black spots to rear or heavily marked with black in some. A few males with crowns about as dark as females. Mantle, scapulars, and tertials black with white tips and notches on feathers, looking vividly barred. Lower back gray-brown, variably barred with black. Uppertail coverts white with fairly narrow black bars. Throat, foreneck, breast, and upper belly solid black; lower belly and undertail coverts white. Outermost undertail coverts with few well-defined black spots. Tail feathers white with a few narrow dark brown to black bars.
Female DescriptionBreeding females vary from almost as bright as males to markedly different. Head and neck stripe distinct in some but not in others. Crown varies from light gray-brown as in winter, to fairly heavily marked with dark brown; never entirely whitish as in male. In plainest females, back drab gray-brown, fringed with paler gray. In some, back heavily barred with dark brown to blackish, but never as vividly black-and-white looking as male. Lower back gray-brown with whitish fringes, uppertail coverts white with light to heavy brown barring. In most extreme individuals, underparts largely black except for lower belly and undertail coverts, but black usually mixed with white, may be thoroughly mottled or even largely white below. Outer undertail coverts often more heavily marked than in male, with dark brown to black spots. Tail feathers white with broad brown bars; tips often tinged brownish.
Immature DescriptionJuvenile similar to winter adult, but with heavily streaked breast and sides and complex pattern of pale dots all over upperparts. May be washed with golden brown.