Lesser scaup duller and have hardly any white at the bill base. Both sexes have white secondary remiges, a blue-grey bill with a black "nail" at the tip and grey feet; the drakes have a bright yellow iris, while that of females is orange or amber and that of immatures is brown. Downy hatchlings look much like those of related species, with dark brown upperparts and pale buff underparts, chin, supercilium and back spots. These birds are not very vocal, at least compared to dabbling ducks. Hens give the namesake discordant "scaup, scaup" call; in courtship drakes produce weak whistles. Hens vocalize
Greater scaup wing shows a white stripe. The females are mostly brown, again with white on the wing. They have dull blue bills and white on the face. Greater scaup nest near water, typically on islands in northern lakes or on floating mats of vegetation. They begin breeding at age two, but start building nests in the first year. The drakes have a complex courtship, which takes place on the return migration to the summer breeding grounds and concludes with the formation of monogamous pairs. Females lay a clutch of six to nine olive-buff-colored eggs. The eggs hatch in 24 to 28