Round-headed diving duck. 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. Very similar to Lesser Scaup; note smoothly rounded head without tall peak, puffier cheeks, more extensive white stripe on wing in flight, and larger, broader bill. Tends to prefer saltwater bays and coves, but also found in freshwater. Can be similar to immature male and female Tufted Duck, but note smoothly rounded head and more extensive white bill base patch in females. Often in flocks with other Aythya ducks.