Lesser Scaup

Overview

The Lesser Scaup is the more common and widespread of North America's two scaup species, breeding across boreal and prairie wetlands and wintering on a broad range of inland and coastal waters. Males show a dark, glossy head, pale gray back, and white flanks similar to the Greater Scaup, but they average smaller and show a distinctly peaked head shape. Because the two scaup species overlap extensively in range and appearance, careful attention to feather and structural details is often needed for a confident identification.

Feather Identification

• Wing stripe: White in the speculum is generally confined to the secondary feathers, with the primaries remaining mostly dark - the reverse of Greater Scaup, where white extends further out the wing.
• Head gloss: Male head feathers typically show a purplish or violet sheen rather than the greenish tone of Greater Scaup, though both can appear to shift with lighting.
• Head shape: A slight peak or bump toward the rear of the crown is a useful structural cue that corresponds with slightly looser crown feathering compared to the smoother, rounded Greater Scaup head.
• Back vermiculation: Fine gray vermiculations on the back are similar to Greater Scaup but the overall body feathering is more compact given the smaller frame.
• Female face patch: The white patch at the base of the bill is present but can be slightly less extensive than in Greater Scaup.

Plumage Notes

Breeding males display a glossy dark head, black breast and rear, pale vermiculated gray back, and white flanks. Females are brown with a well-defined white patch around the bill base. Eclipse plumage in males resembles the female but retains some gray back feathering. Lesser Scaup undergo a complete molt after breeding, becoming flightless for a period as new flight feathers grow in synchronously. Juveniles resemble adult females and gain full adult male features over their first year, with head gloss becoming more pronounced as feathers mature.

Habitat & Range

Lesser Scaup breed primarily across the prairie pothole region and boreal forest of North America, nesting near freshwater marshes and lakes. In migration and winter they are the more inland-oriented of the two scaup species, commonly found on reservoirs, lakes, and sheltered bays across much of the continental United States, Mexico, and Central America. The species is strongly migratory, undertaking long movements between northern breeding grounds and southern wintering areas.

Behavior & Field Notes

Lesser Scaup dive frequently to forage on aquatic invertebrates and plant material along lake and reservoir bottoms. They are highly social, forming large mixed rafts with other diving ducks during migration and winter. Courtship displays involve head-bobbing and soft whistled calls from males, while females give a harsher, growling note. Nests are built on the ground close to water, often in dense vegetation, with the female solely responsible for incubation and duckling care. Flight is fast with rapid wingbeats, typically in tight flock formation low over the water.