Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) BREEDING: Formerly throughout North America from central Alaska to western Hudson Bay (James Bay), southeast to Nova Scotia, with the southern limit extending to northwest Mississippi and eastern Arkansas in the east and possibly California in the west. Present breeding range includes Alaska (Interior, Southcentral, Gulf of Alaska, and Chilkat basin), Yukon, British Columbia, Alberta, Washington, Oregon, Nevada, Montana, Idaho, Wyoming, South Dakota, Minnesota, Wisconsin, Michigan, Saskatchewan, and Ontario (Mitchell 1994). Alaska contains over 85% of the world's breeding population, and breeding areas outside of Alaska are very localized (Mitchell 1994).
NONBREEDING: Formerly from the present range in southeast Alaska (a few small flocks along the Gulf of Alaska), along the British Columbia coast, Washington, Oregon, and occasionally California but historically extending to southern California, possibly Arizona and New Mexico, along Gulf Coast to central Florida, and along Alantic coast as far as ice free waters existed (Mitchell 1994). Present range includes the Gulf of Alaska coast, southeast Alaska, British Columbia, western Washington, western Oregon, occasionally California, eeastern Nevada, western Utah, southern Montana, eastern Idaho, northwestern Wyoming, southwestern South Dakota, and small resident populations in the midwestern states, Saskatchewan, and Ontario (Mitchell 1994). In the contiguous United States and adjacent Canada, the highest winter densities occur in western Wyoming, western British Columbia (coast and interior lakes), southeastern Oregon, and southwestern Montana, mainly on wildlife refuges (Root 1988).
Interior population (resulting from transplants and captive propagation) consists of flocks in Lacreek National Wildlife Refuge, South Dakota, and Hennepin County Park Reserve District, Minnesota; these gradually are exhibiting southward movement in fall but still are dependent on supplemental feeding.
Rocky Mountain population nests in the Rocky Mountains of Canada and the United States (Idaho, Montana, Wyoming) and winters primarily in the Greater Yellowstone Ecosystem (Spahr et al. 1991). Breeding areas in Canada include Peace River area of Alberta and British Columbia and Toobally Lakes area of Yukon, plus some areas farther north in Northwest Territories (Johnson and Herter 1989). U.S. flocks of the Rocky Mountain population currently summer in three locations (1) the Tri-state Area of eastern Idaho, southwestern Montana, and western Wyoming, (2) the Ruby Lake National Wildlife Refuge, and (3) Malheur NWR and Summer Lake area of Oregon. Trumpeter swans at Ruby Lake and Malheur NWRs were derived primarily from swans that were transplanted from Red Rock Lakes NWR, beginning in 1941 (Pacific Flyway Study Committee 2002).