Mareca strepera

Considered by some authors as two separate species, A. strepera (common gadwall) and A. couesi (Coues' gadwall), the latter now extinct (AOU 1983). Formerly (AOU 1983, 1998) considered part of Anas, but now treated as separate on the basis of genetic data (Gonzalez et al. 2009) which indicate that Anas as previously constituted was paraphyletic, and further that it consisted of four deeply divergent clades, now recognized as the separate genera Sibirionetta, Spatula, Mareca, and Anas (cf. Livezey 1991). Linear sequence of genera and species follows Gonzalez et al. (2009). (AOU 2017).

BREEDS: North America: southern Alaska, southern Yukon, southern Mackenzie (north to near Yellowknife; Can. Field-Nat. 106:254-256), northern Saskatchewan, central Manitoba, southern Ontario, southwestern Quebec, Prince Edward Island, Anticosti Island (rarely), and the New Brunswick-Nova Scotia border south locally to southern California, southern Nevada, northern Arizona, southern New Mexico, northern Texas, southern Kansas, Iowa, centralMinnesota, southern Wisconsin, northern Ohio, northern Pennsylvania (formerly), and, on the Atlantic coast, to North Carolina (one isolated breeding area in northern Alabama); also in the Old World (AOU 1983). Highest breeding densities occur in the northern Great Plains and intermountain valleys of the western U.S.; some portions of Alaskan, Pacific, and Atlantic coasts also have important breeding populations (Ringelman 1990). Range may be expanding eastward. WINTERS: North America: southern Alaska, southern British Columbia, Idaho, Colorado, southern South Dakota, Iowa, the southern Great Lakes, and Chesapeake Bay on the Atlantic coast (rarely from New Brunswick and Nova Scotia) south to northern Baja California, Oaxaca, the state of Mexico, Puebla, Veracruz, Tabasco, Yucatan, the Gulf Coast, Florida, the Bahamas, western Cuba, and (formerly) Jamaica; also in Old World (AOU 1983). Major wintering areas include coastal Louisiana and Texas, Gulf Coast of Mexico to Yucatan Peninsula, central and southern Atlantic coast of U.S., Central Valley of California, and much of the west coast of Mexico (Ringelman 1990); also northwestern Utah (Bear River refuge) and southeastern Missouri (Mingo refuge) (Root 1988). Formerly resident (COUESI group) in the northern Line Islands (Washington and New York islands); now extinct (AOU 1983).