[order] ANSERIFORMES | [family] Anatidae | [latin] Aythya affinis | [authority] Eyton, 1838 | [UK] Lesser Scaup | [FR] Fuligule a tete noire | [DE] Kleine Bergente | [ES] Porron bola | [NL] Kleine Toppereend
Aythya is a genus of diving ducks. It has twelve described species. Aythya shihuibas was described from the Late Miocene of China. An undescribed prehistoric species is known only from Early Pleistocene fossil remains found at Dursunlu, Turkey; it might however be referrable to a paleosubspecies of an extant species considering its age. The Miocene “Aythya” arvernensis is now placed in Mionetta, while “Aythya” chauvirae seems to contain the remains of 2 species, at least one of which does not seem to be a diving duck.
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. Males: 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. Females: 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.
Listen to the sound of Lesser Scaup
Copyright remark: Most sounds derived from xeno-canto
North America : widespread
In winter, Lesser Scaups are often found in dense flocks of hundreds and even thousands, on lakes, reservoirs, rivers, and sheltered bays. Lesser Scaup are far more likely than Greater Scaup to be found on fresh water inland during the winter. In summer, nesting habitat is small wetlands with emergent vegetation in boreal forests and parklands. During migration, Lesser Scaups spend their time on rivers, lakes, and large wetlands.
Lesser scaup have one of the most extensive breeding ranges of North American ducks. Their breeding range extends from the northern USA through the prairie pothole region, to the Bering Sea, with the largest breeding populations occurring in the boreal forest 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.
Lesser scaup dive to feed on seeds of pondweeds, widgeon grass, wild rice, sedges, and bulrushes. They also feed on crustaceans, mollusks, aquatic insects, and small fishes.
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Lesser and greater scaup are counted together, because they are difficult to distinguish during aerial surveys. Lesser scaup are estimated to constitute roughly 89% 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 cause are little understood. The 2001 breeding population survey was approximately 3.3 million birds, an 8% decrease from last year’s estimate.
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 common winter visitor to Central America, the Caribbean and northern Colombia; occasional winter visitor Ecuador, Venezuela and Trinidad. Vagrant S to Ecuador and Surinam, N to Greenland; two recent records from Britain may be of truly wild birds.