Very similar to Lesser Scaup in plumage; best separated by careful study of head and bill shape. Males have black breast, medium gray back, white sides, and yellow eye. Head appears black with a greenish sheen in good lighting, never purplish. Females are brown overall, grayer on body in winter, with white patch at base of bill and yellow eye. To distinguish from Lesser Scaup, note smoothly rounded head without tall peak and puffier cheeks. Also larger, broader bill and more extensive white stripe on wing in flight. Tends to prefer saltwater bays and coves, but also found in freshwater. Often in flocks with Lesser Scaup, Redhead or other Aythya ducks.