The Lesser Scaup is a medium-sized diving duck with a small peak at the back of the head. From the small peak, the back of the head and neck is flat, not rounded as it is on Greater Scaup. They measure 39 to 46 centimeters in length, with a wingspan of 68 to 78 centimeters. At a distance, breeding male Lesser Scaup are black and white, but closer views reveal an iridescent purple to green sheen on the head, a finely barred black-and-white back, a bluish bill, and a yellow eye. Females are brown overall with a darker brown head and a white patch next to the bill, but not all females have a white patch. Nonbreeding males look like a cross between a female and a breeding male: a mottled brown-and-gray body and a blackish head. During migration and winter, Lesser Scaup form large flocks on lakes, bays, rivers, and larger wetlands. They tend to form tight groups and mix with other diving ducks such as Canvasbacks, Redheads, Greater Scaup, and Ring-necked Ducks. During winter, look for Lesser Scaup on lakes, reservoirs, coastal bays, and estuaries. They are more likely to use inland lakes than Greater Scaup. During the breeding season, they are more commonly found in marshes of northern North America where they nest. This species is of low conservation concern.
In lakes or wetlands with a lot of tiny crustaceans called amphipods that float about in the water, Lesser Scaup often look like they are doing somersaults or other odd acrobatics as they try to pick off the amphipods that cling to their belly feathers as they swim through the water.
Lesser Scaup is the most abundant diving duck in North America, with a global breeding population estimated at 3.8 million.
Lesser Scaup chicks don't waste any time. As soon as their down dries, under the water they go. The little ones are a bit too buoyant to stay down for long, but by the time they are 5 to 7 weeks old, they can dive for up to 25 seconds and swim up to 60 feet underwater.
Source: Lesser Scaup Overview and Identification Information, All About Birds, The Cornell Lab of Ornithology