Anas crecca

Livezey's (1991) phylogenetic analysis and classification (supergenera, subgenera, infragenera, etc.) of dabbling ducks (based on comparative morphology) listed A. crecca and A. carolinensis as separate species. Zink et al. (1995), however, found no evidence of genetic differentiation between populations in Asian and North American sides of Beringia. The American Ornithologists' Union (1998 and subsequent supplements in 2000, 2002, 2003, and 2004) accordingly has treated A. crecca and A. carolinensis as conspecific. In contrast, in a phylogeny of dabbling ducks, Johnson and Sorenson (1999) presented evidence that A. crecca and A. carolinensis are separate species, and the British Ornithological Union (2001) subsequently recognized them as such.

Holarctic. BREEDS: north-central Alaska, northwestern and central Canada south to California, northern New Mexico, northern Nebraska, Minnesota, northern Ohio, western New York, Maine, Nova Scotia; Iceland, northern Eurasia, Aleutians south to southern Spain, northern Italy, southern Russia and northwestern China. WINTERS: in North America, mostly in the U.S., regularly to central Mexico and Antilles; also Hawaii; widely in Old World. In the U.S., the highest winter densities occur in western Texas, northern Utah, Kansas, Mississippi-Arkansas, and southeastern North Carolina; except for the latter, these are associated with national wildlife refuges (Root 1988).