About the Greater Scaup
Greater scaup breed on the tundra and in the Boreal Forest zones from Iceland across northern Scandinavia, northern Russia, northern Siberia and the western North American Arctic. It is estimated that three-quarters of the North American population breeds in Alaska. Greater scaup nest predominantly on islands in large lakes and lay an average of 9 eggs.
Latin: Aythya marila
Average length: M 18.6", F 17"
Average weight: M 2.32 lbs., F 2.15 lbs.
Greater and lesser scaup are often found together, but the larger size of the greater scaup is very obvious. Male greater scaup also have a larger, more round, green-tinted head than male lesser scaup. Male greater scaup have a glossy black head tinted green. The neck, breast and upper mantle are glossy black, and the flanks and belly are white, sometimes with gray vermiculations on the lower flanks. The back is whitish with fine black vermiculations, and the tail and upper- and under-tail coverts are black. The wing has a broad white speculum spanning nearly the entire length of the primaries and secondaries. The bill is a light blue-gray with a black nail, the legs and feet are gray and the iris is yellow. Female greater scaup are brown with white oval patches around their bills. The female's bill is similar to that of the male, but slightly duller, and the legs and feet are gray.
Greater scaup dive to feed on aquatic plants and animals. In coastal areas, mollusks constitute the principle diet items. In freshwater habitats, seeds, leaves, stems, roots and tubers of aquatic plants (sedges, pondweeds, muskgrass, wild celery, etc.) are important items.
Greater and lesser scaup are counted together, because they are difficult to distinguish during aerial surveys. Greater scaup are estimated to constitute roughly 11 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.
Migrating and Wintering
Greater scaup make extensive flights across the boreal forests of Canada prior to reaching their wintering grounds along the Atlantic coast and the Great Lakes, or migrate offshore from Alaska to their wintering grounds along the Pacific Coast. Greater scaup occasionally are observed during winter in Central America and the Caribbean.
About the Lesser Scaup
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.
Latin: Aythya affinis
Average length: M 17", F 16.5"
Average weight: M 1.8 lbs., F 1.6 lbs.
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. 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.
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.
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.
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).
[information by Ducks.org]