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Lesser Scaup

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Latin: Aythya affinis
Average length: M 17", F 16.5"
Average weight: M 1.8 lbs., F 1.6 lbs.

Description: Lesser and greater scaup are often found together. The smaller size of the lesser scaup is very obvious. Lesser scaup also have a smaller, less-round, purple-tinted head than greater scaup. Male lesser scaup have a glossy black head with a purple cast. The neck, breast and upper mantle are glossy black. Vermiculations on the sides and flanks are olive brown and contrast with the white chest and belly. The back is light gray with broad heavy vermiculations of sooty black. The tail, upper and under-tail coverts are black. The wing has a white speculum and the inner primaries are light brown, becoming darker towards the tips and outer primaries. The bill is a light blue-gray with a black nail, the legs and feet are gray and the iris is yellow. In courtship the male utters weak whistling notes. Female lesser scaup have a brownish head, neck and chest, and white oval patches around their bills. The back, rump and scapulars are dark brown and the speculum is white. The bill is similar to that of the male but slightly duller, the legs and feet are gray and the iris is yellow. The female has weaker growl than greater scaup.


Breeding: Lesser scaup have one of the most extensive breeding ranges of North American ducks. Their breeding range extends from the northern United States through the Prairie Pothole Region, to the Bering Sea, with the largest breeding populations occurring in the boreal forests of Canada. They typically breed near interior lakes, ponds and sedge meadows. Deeper, more permanent wetlands are preferred. Lesser scaup prefer wetland habitats with emergent vegetation, such as bulrushes, since they often harbor abundant populations of aquatic insect larvae. Females nest in close proximity to open water and lay an average of 9 eggs.


Migrating and Wintering: The majority of lesser scaup migrate through the Central and Mississippi flyways to wintering areas along the Gulf of Mexico and coastal Florida. Fresh and brackish water wetlands and open bays are preferred wintering habitats. Lesser scaup are a common winter visitor to Central America, the Caribbean and northern Colombia and an occasional winter visitor to Ecuador, Venezuela and Trinidad (Scott and Carbonell, 1986).


Population: Lesser and greater scaup are counted together, because they are difficult to distinguish during aerial surveys. Lesser scaup are estimated to constitute roughly 89 percent of the continental scaup population. Scaup populations have steadily declined since the 1980s. Contaminants, lower female survival and reduced recruitment due to changes in breeding habitat or food resources are thought to be the primary factors contributing to the decline, although causes are little understood.


Food habits: Lesser scaup dive to feed on seeds of pondweeds, wigeon grass, wild rice, sedges and bulrushes. They also feed on crustaceans, mollusks, aquatic insects and small fish.


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