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
Lesser scaup where the white extends to the eye region. But especially with juveniles, the bi-colored bill of hybrids is most diagnostic. Hybrid combinations that are known from the wild and resemble the lesser scaup are: In theory, each and every "Aythya" species is able to produce potentially fertile hybrids with any other, though due to their different ranges and behavioral cues given during courtship most of these hybrids are only known from birds kept in captivity without conspecific mates. Their breeding habitat is inland lakes and marsh ponds in tundra from Alaska through western Canada to western Montana; few breed east