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ADULT MALE Has dark green head (Greater scaup) or black (Lesser scaup) and dark breast; both can look black in poor light. Belly and flanks are white and back is pale gray, palest toward front. Vent is black; note bright yellow eye. Eclipse plumage pattern recalls adult male, but pale elements are buffy gray.
ADULT FEMALE Has mainly dark brown plumage, palest and grayest on flanks and back; white belly is seen in flight. Note striking white patch at base of bill.
JUVENILE Similar to adult female.

Length: 15-20"

Mostly silent

Bulky, diving duck. Feeds on submerged roots, seeds, and invertebrates. Superficially similar to slightly smaller Lesser Scaup, but size is not always a useful means of field identification. Head shape is generally reliable in relaxed birds: rounded in Greater, but distinctly peaked in Lesser. In flight, more of the upper-wing flight feathers appear whitish in Greater than in Lesser. At close range, black tip to otherwise dark gray bill is more extensive in Greater than Lesser (hard to judge in field).