Lesser Scaup

Lesser Scaup

webpage header of lesser scaup


  • Common: Lesser Scaup
  • Scientific: Aythya affinis


Conservation Status

  • State recognized as Indigenous

Species Information

The lesser scaup is a medium-sized black and white diving duck (Family: Anatidae), one of the most abundant and widespread ducks in North America. Lesser scaups winter in the Main Hawaiian Islands (MHI), typically arriving in October and departing for Alaska or Canada as early as February. Lesser scaups feed primarily on aquatic invertebrates such as insects, crustaceans, and mollusks; seeds and vegetative parts of aquatic plants are also important. As with many ducks, lesser scaups have difference in plumage depending on sex, with breeding males showing a dramatic contrast between their white body and black head, neck, throat, and rump. Female plumage is a more monochromatic dark brown. Nonbreeding male plumage shows less contrast, with the body becoming more brown at the margins. Being gregarious, lesser scaups form pair bonds but remain promiscuous during breeding. They are known to hybridize with four other North American duck species (greater scaup, ring-necked duck, redhead, and canvasback) in the wild, and with four others (tufted duck, European pochard, American wigeon, and wood duck) in captivity.


Common throughout the southern and western United States and Mexico during the winter, shifting to the northernmost central U.S., west central Canada, and Alaska during the breeding season. Lesser scaups are also common through Eurasia. In Hawai‘i, lesser scaups have been sighted routinely on all of the MHI, but have not been recorded in the NWHI.


Winter diet of lesser scaups varies geographically, but specific dietary habits of Hawaiian migrants have not been documented in the published literature. On the continental U.S., lesser scaups are found along lake coastlines, reservoirs, and fresh to brackish coastal bays and estuaries. During severe weather, they may move to more saline waters, and they are more common in such saline habitats than other diving ducks. In Texas, they are found on hypersaline estuaries, usually close to inland freshwater ponds where individuals go to drink.


Primary threats include the following:

    • Loss of wetland habitat to development, pollution, or habitat-modifying invasive plants. 
    • Avian disease.

Plans & Projects

Additional Resources 

For more information and references visit the DLNR State Wildlife Action Plan factsheets. DOFAWʻs species pages and State Wildlife Action Plan fact sheets are provided for general information and are not meant to be a citable, original source of data. If you are a student, researcher, or writer looking for a citable source, please explore the references below or find other original data sources, rather than citing these webpages. The references below were provided by the authors of the State Wildlife Action Plan fact sheets at the time of drafting:

  • Austin JE, Custer CM, Afton AD. 1998. Lesser scaup (Aythya affinis). In The Birds of North America, No. 338 (Poole A, Gill F, editors). Philadelphia, (PA): The Academy of Natural Sciences; and Washington DC: The American Ornithologists’ Union.