- Large, stocky diving duck.
- White patch in wings.
- Male with white comma-shaped patch around eyes.
- Female with whitish patches on face.
Male DescriptionEntirely black, without gloss. Inverted comma-shaped white patch surrounding eyes. Pale edges to body feathers may produce scalloping or barring on back and sides. Belly sometimes white. Bill black at base, including the hump, with reddish sides, and orange nail. Eyes white. Legs red, with black webs and joints.
Female DescriptionDark brownish. Head may be all dark, or have poorly defined light patches at base of bill and on cheek. Bill dark grayish black with reddish wash and light band next to nail. Eyes dark brown. Legs and feet reddish with black webs.
Immature DescriptionSimilar to adult female but with paler belly and more distinct face patches.