Lesser Scaup

Lesser Scaup

Summary:

Profile Lesser Scaup
[order] Anseriformes |

[order] Anseriformes | [family] Anatidae | [latin] Aythya affinis | [UK] Lesser Scaup | [FR] Fuligule à tête noire | [DE] Kleine Bergente | [ES] Porrón bola | [IT] Moretta grigia minore | [NL] Kleine Topper

Kleine Topper determination

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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.

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 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.

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 a large range, with an estimated global Extent of Occurrence of 5,200,000 km². It has a large global population estimated to be 3,000,000 individuals (Wetlands International 2002). Global population trends have not been quantified, but the species is not believed to approach the thresholds for the population decline criterion of the IUCN Red List (i.e. declining more than 30% in ten years or three generations). For these reasons, the species is evaluated as Least Concern. [conservation status from birdlife.org]


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.

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.

Specification

  1. Measurements
  2. spanwidth min.: 68 cm
  3. spanwidth max.: 77 cm
  4. size min.: 38 cm
  5. size max.: 46 cm
  6. Breeding
  7. incubation min.: 21 days
  8. incubation max.: 27 days
  9. fledging min.: 47 days
  10. fledging max.: 54 days
  11. broods 1
  12. eggs min.: 8
  13. eggs max.: 10
  14. Conservation Status
  15. Kleine Topper status Least Concern

Subspecies

  1. Polysticta affinis
  2. Aythya affinis
  3. NA widespread
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