Lesser scaup by similar-looking "Aythya" hybrids. Except for hybrids between the two scaup species, the most reliable mark is the black bill-tip of hybrids, whereas in the scaups only the very point ("nail") of the bill is black. This is even recognizable at considerable range, as the scaups' bills appear uniformly grey from a distance, whereas those of hybrids look two-colored. European hybrids typically involve the tufted duck ("A. fuligula"), yielding offspring that have a small nape crest unlike any European "Aythya" species. Female and immature hybrids typically lack the white bill base, except in those between lesser scaup and ring-necked duck,
Greater scaup Greater scaup breed in the tundra and the boreal forest; it is estimated that 75% of the North American population breed in Alaska. They typically nest on islands in large northern lakes. Greater scaup begin breeding when they are two years old, although they may start nesting at age one. Drake greater scaup have a soft, quick whistle they use to attract the attention of hens during courtship, which takes place from late winter to early spring, on the way back to their northern breeding grounds. Female greater scaup have a single pitch, a raspy “arrr-arrr-arrr-arrr-arrr” vocalization. The courtship is