Lesser Scaup

Aythya affinis

North America's most abundant diving duck. Your message rides with the raft.

Population: ~3.7 million mature individuals (2018 estimate, IUCN/BirdLife 2021 assessment); Cornell cites ~3.8 million; down from ~6.9 million in the 1970s per Wikipedia/USGS survey data
Habitat: Freshwater lakes, arctic/boreal marshes and ponds (plus reservoirs and agricultural ponds in the southern US) for breeding; during winter uses freshwater or brackish lakes, rivers, coastal lagoons, bays, and sheltered estuarine/marine waters
Fun fact: The Lesser Scaup is North America's most abundant diving duck, yet its purple (vs. green) head sheen is an unreliable field mark that varies with light — head shape (a peaked crown toward the back, less bulging forehead) is the more diagnostic way to separate it from the closely related Greater Scaup.
Range: Breeds from Alaska through western/central Canada to the northern Great Plains and western Montana; winters from the Great Lakes/southern US and Pacific/Atlantic coasts south through Mexico, Central America, the West Indies, and Bermuda to northern South America (Colombia); rare vagrant to Europe, Hawaii, and Japan
Diet: Omnivorous diving duck; mainly mollusks (mussels, clams) plus aquatic plant seeds and vegetation (sedges, bulrushes, pondweeds, wild celery, wild rice), supplemented with crustaceans, aquatic insects, and small fish especially in winter
Size: 0.43 m
Wingspan: 0.73 m
Lifespan: 18 years

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