The Lesser Scaup (Aythya affinis) is a fairly common winter visitor to lakes and larger ponds here in southeastern Arizona. I spotted this male Lesser Scaup begging for handouts with the rest of the park ducks in Tucson's Lakeside Park in late December of 2006.
A male Lesser Scaup has yellow eyes, a finely barred gray back, whitish gray sides, and a black head, chest, and rump. Unlike the white-ringed bill of a very similar male Ring-necked Duck (Aythya collaris), the only marking on the otherwise plain gray bill of a male Lesser Scaup is a small, black tip.
Male Lesser Scaup are extremely similar to the closely related male Greater Scaup (Aythya marila), but their head shape and head and neck feather sheen can be used to distinguish them. A male Lesser Scaup has a tall, peaked head and a purplish sheen to his black head and neck feathers, while a male Greater Scaup has a lower, rounder head and a greenish sheen to his black head and neck feathers.
Female Lesser Scaup are brown where the males are black and have a white ring of feathers around the base of their bills. They are very similar to female Greater Scaup.