Aythya valisineria

Considered a superspecies with A. Ferina by some authors (AOU 1998).

BREEDS: central Alaska, central Yukon, northern Northwest Territories (Mackenzie Delta), and southeastern Manitoba south to northern California, western Nevada, northern Utah, northern Colorado, Nebraska, and Minnesota. WINTERS: southern British Columbia, northwestern Montana, northern Colorado, northern Tennessee to eastern Great Lakes, Chesapeake Bay, eastern Massachusetts, and Quebec, south to central Mexico, Gulf states, northern Florida; rarely Hawaii. In the U.S., the highest winter densities occur in the Chesapeake Bay region and at the Bitter Lake NWR in eastern New Mexico (Root 1988). Over 25% of the continental population winters in Louisiana. Winter populations in the Atlantic flyway are more concentrated than those in Mississippi flyway (Serie et al. 1983). About 83% of the western North American population overwinters for 4-6 months in California, primarily in San Francisco Bay (Reinecker, 1985, Calif. Fish Game 71:141-149).

Has suffered from loss of breeding habitat (drained and cultivated). Susceptible to lead poisoning due to ingestion of shot while feeding (this threat should gradually disappear with lead shot ban). Declines in the western U.S. are not directly attributable to contaminants acquired by populations wintering in San Francisco Bay; however, evidence of high and increasing Se levels and elevated Hg levels warrant future monitoring (Miles and Ohlendorf 1993).