Tundra Swan Population Survey

Swans breeding on the lower Alaska Peninsula make up the most southerly and westerly breeding Tundra Swans in North America. Biologists at Izembek National Wildlife Refuge have monitored tundra swans on the lower Alaska Peninsula since 1978 using aerial surveys. These surveys are conducted in the spring and have been useful in identifying key nesting habitats as well as obtaining an index of population numbers for tundra swans between Herendeen Bay and False Pass on the Alaska Peninsula.

Banding and neck collaring efforts in the 1980’s and 2000’s revealed that swans nesting on and near Izembek Refuge are essentially non-migratory, wintering around Izembek Lagoon or on nearby Unimak and Sanak Islands. Unimak island provides ice-free habitat even in severely cold winters due to geothermal activity that keeps several marine lagoons from completely freezing over. In more mild winters with less ice cover, Tundra Swans will overwinter in Izembek. This population is the only known essentially non-migratory population of Tundra Swans in North America.

This unique population has historically exhibited low densities and periodic mass emigrations. These low swan densities in the Izembek area may be attributed to sub-optimal habitat, low reproductive output, or predation of nests by brown bears and wolves. The low numbers and isolated nature of the Izembek population merit continuing monitoring efforts of tundra swans on the Alaska Peninsula so refuge staff may understand population trends, the impacts of human use of the refuge on nesting waterfowl, and determine if management actions would be necessary to prevent the loss of this population.