Lesser Scaup
Aythya affinis

Conservation status | Although it is still abundant, the total population has declined significantly in recent decades, and the causes are not well understood. |
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Family | Ducks and Geese |
Habitat | Marsh ponds (summer), lakes, bays, estuaries. Summers around large marshes in prairie or forested regions. Winters on lakes, reservoirs, rivers, sheltered areas of coastal bays. Overlaps extensively with Greater Scaup, especially in winter, but at that season the Lesser is far more likely to be found on freshwater lakes and ponds well inland. |
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Feeding Behavior
Forages by diving and swimming underwater; sometimes by dabbling or up-ending in shallow water. Sometimes feeds at night.
Eggs
9-11, sometimes 8-14. Olive-buff. Incubation is by female only, 21-27 days. Young: Leave nest shortly after hatching, go to water. Young are tended by female but feed themselves. 2 or more broods of young may join under care of several adult females. Age at first flight 47-54 days after hatching.
Young
Leave nest shortly after hatching, go to water. Young are tended by female but feed themselves. 2 or more broods of young may join under care of several adult females. Age at first flight 47-54 days after hatching.
Diet
Includes mollusks, plant material. Diet varies with season and habitat, but animal matter may predominate, especially mollusks such as clams and snails, also aquatic insects, crustaceans. Also eats plant material such as stems and leaves of sea lettuce, pondweeds, wild celery, plus seeds of pondweeds, sedges, grasses, and others. Birds on the Great Lakes may feed heavily on the introduced zebra mussel.
Nesting
Probably first breeds at age of 2 years in most cases. Elements of courtship display by male include a shake of the head, followed by throwing the head far back and bringing it forward very quickly; exaggerated bowing movements; ritualized preening. Some displays may be performed underwater. Nest site is usually on dry land close to water, often on islands in lakes, surrounded by good cover of vegetation. Stands of bulrush in marshes especially favored. Nest is a slight depression with addition of some dry grass, lined with down.
Illustration © David Allen Sibley.
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Text © Kenn Kaufman, adapted from
Lives of North American Birds
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Migration
Migrates in flocks. Main migration is rather late in fall and early in spring.

- All Seasons - Common
- All Seasons - Uncommon
- Breeding - Common
- Breeding - Uncommon
- Winter - Common
- Winter - Uncommon
- Migration - Common
- Migration - Uncommon
See a fully interactive migration map for this species on the Bird Migration Explorer.
Learn moreSongs and Calls
Seldom heard; sharp whistles and guttural scolding notes.Learn more about this sound collection.