Species: Histrionicus histrionicus

H - >2,500,000 square km (greater than 1,000,000 square miles) - H - Holarctic. Nesting occurs in Eurasia and two disjunct regions in North America. Pacific population breeds from western Alaska (see Johnson and Herter 1989 for details), northern Yukon, northern British Columbia, and southern Alberta south to Oregon, Idaho, Wyoming, and east of the Continental Divide in Montana (perhaps historically in California and Colorado). The Atlantic population breeds from Baffin Island (at least formerly), Greenland, and Iceland through central and eastern Quebec, eastern Labrador, northern Newfoundland (perhaps historically much more widely in the North Atlantic region). This duck occurs in summer in Mackenzie Valley and near Great Slave Lake, Northwest Territories. In the Palearctic, harlequin ducks breed in Iceland and Greenland, and from the Lena River in Siberia east to Kamchatka and south to northern Mongolia and the Kurile Islands (American Ornithologists Union 1983). During the nonbreeding season, harlequin ducks occur in Eurasia; Aleutian and Pribilof islands south to central California; southern Labrador, Newfoundland, Nova Scotia, south to Maryland (but mostly north of Cape Cod); accidental in Hawaii; they are much more abundant in the Aleutians than farther south in southwestern Canada and U.S. Pacific Northwest.