Large scoter, with distinctive white patch on wing. Dark chocolate-brown overall; males are darker than females and have small white mark under eye, dark knob on the bill, and pink bill tip. Females have two rounded white patches on face. At a distance, separated from Surf Scoter by more sloping head shape and white in the wing. Winters on coastal waters and large freshwater lakes. Occasionally found on large inland lakes during migration. Dives frequently, feeding on mollusks and crustaceans.