Gavia adamsii

Gavia adamsii constitutes a superspecies with the common loon (Gavia immer) (AOU 1998).

Apparently rare and local throughout most of range (northwestern Canada, Alaska, northeastern Eurasia); North American population estimated at 16,000 individuals. Highly sensitive to disturbance and susceptible to the effects of oil spills.

Breeding range extends patchily throughout the subarctic and arctic tundra of northern Alaska, Canada, and Eurasia. In Alaska, nesting occurs from the Canning River westward to Point Lay and also includes St. Lawrence Island and coastal areas of the Seward Peninsula. In Canada, breeding extends from just east of the MacKenzie River Delta to Hudson Bay, including northern islands. Breeding is most common on Banks and Victoria Islands and in the lake district from Great Slave Lake northeast to northern Hudson Bay, and nesting occurs sparsely elsewhere. In Russia, nesting occurs in narrow strip of coastal tundra from the Chukchi Peninsula in the east to the Taymyr Peninsula and the areas of the Novaya Zemlya River and Pechora River in the west. Small numbers have been reported breeding in Finland and Norway (Earnst 2004).

Migration occurs regularly along the coastlines of northern Canada and northern and northwestern Alaska and rarely along the western Alaska coast (Earnst 2004).

In winter, the species is regularly but sparsely distributed in nearshore marine waters from Kodiak Island though Prince William Sound, and throughout southeast Alaska and British Columbia. Irregular wintering occurs southwest of Kodiak Island along the Aleutian Islands and along the coast from Washington to Baja California. Several reliable inland sightings exist for migrating and wintering loons in western and central North America. Immatures and possibly some nonbreeding adults remain on wintering grounds throughout the year. Eurasian population winters primarily around Scandinavia and along the Pacific Coast of Siberia, uncommonly in northern Japan, and rarely in China, Great Britain, and continental Europe (Earnst 2004).

Breeding and nonbreeding occurrences have not been circumscribed or enunerated, but this species appears to be represented by a large number of breeding occurrnces.

Threats include breeding habitat loss and degradation from oil exploration and development, oil spills and other contaminants, reduction of prey base from overfishing, native subsistence hunting pressure, mortality in commercial, subsistence and research fishery bycatch, and predation (Earnst 2004).