Forest and Rangeland Birds of the United States

Natural History and Habitat Use

Canvasback -- Aythya valisineria

RANGE: Breeds from central Alaska and northern Yukon to western Ontario and south to south-coastal Alaska; locally in inland areas to northeastern California across to northern Utah, central New Mexico, northwestern Iowa, and southern Ontario. Winters along the Pacific Coast from the central Aleutians and south-coastal Alaska south to Baja California, from Arizona and New Mexico to the Great Lakes, and, on the Atlantic Coast, from New England south to the Gulf Coast and Mexico.

STATUS: Locally common; numbers are declining due to loss of breeding habitat through drainage and drought.

HABITAT: Prefers shallow prairie marshes, 10 acres or less, or other permanent wetlands with stable water levels, bordered by cattails and bulrushes, with little, if any, wooded vegetation around the shoreline. Large lakes of 150 acres or more, marshes, and rivers with submerged beds of sago pondweed are favored during migration. Winters primarily on estuaries and sheltered bays, sometimes on deep, freshwater lakes, where wild celery and pondweeds thrive.

SPECIAL HABITAT REQUIREMENTS: Marshes, ponds, lakes, and rivers bordered by emergent vegetation and with enough open water for taking off and landing.

NEST: Usually nests over water 6 to 24 inches deep in bulrushes, reeds, or cattails, sometimes on a muskrat house, rarely on dry ground. Attaches nest to surrounding plants or built on a mat of floating dead plants, 3 to 60 feet from edge of open water.

FOOD: Dives in shallow water, usually 3 to 12 feet deep, for food, which is 80 percent vegetative material. In the Northeast, prefers seeds and vegetative parts of wild celery; in the Southeast and the West, primarily consumes pondweeds; also feeds on water plantains, grasses, sedges, mollusks, and insects.

REFERENCES: Bellrose 1976, DeGraff et al. 1980, Evans and Bartels 1981, Johnsgard 1975b, Palmer 1976b, Stoudt 1982, Terres 1980.

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