Tundra Swan Life History

Habitat

Tundra Swans breed on lakes, ponds and pools situated along river deltas in Alaska and Canada, with some birds nesting at inland sites below treeline. Breeding birds prefer areas with extensive wetlands and lakes with long shorelines that support pondweed. In fall, flocks gather (or “stage”) along the brackish shorelines of river deltas before moving south, stopping along the way at wetlands in boreal forests. Wintering flocks gather on estuaries, lakes, bays, ponds and rivers, often situated close to agricultural fields where the birds feed. Back to top

Food

Tundra Swans eat mainly plant matter, although they also eat mollusks and arthropods. Plant foods include tubers, stems, and leaves of aquatic vegetation such as Carex sedges, saltmarsh starwort, alkali grass, pondweed, and Nostoc algae. During migration and on the wintering grounds (especially in the East) look for Tundra Swans in fields gleaning corn, soybeans, and rice left after the harvest, and feeding on growing winter crops such as winter wheat, rye and barley. In the Chesapeake Bay Tundra Swans use their bills and feet to root up clams from the muddy bottom. When feeding on the water Tundra Swans “tip up” like dabbling ducks to reach submerged vegetation. On their arctic breeding grounds they also graze on upland or wet-meadow tundra. Back to top

Nesting

Nest Placement

Nests are typically placed near a large body of water, either on an island or in upland or wet meadow tundra. Tundra Swans often place the nest on the low, elevated ridges between small ponds (known as polygon ponds) that are created by repeated thawing and freezing of arctic soil.

Nest Description

Both members of the pair build the nest, a mound of vegetation including grasses, sedges, other tundra plants, lichens, and moss. The birds pull material from within about 10 feet of the nest site in a ritualized set of behaviors called “forward building” and “side building.” The female uses her feet and body to scrape a cup-shaped bowl into the mound, although both pair members deepen the bowl with their bill. Built in 4 - 9 days before egg laying starts, the nest reaches 8 inches in height, 10 - 20 inches across at the base, with a cup measuring 7.5 - 15 inches wide and 4 - 8 inches deep. The pair continues to work on the nest during egg laying and incubation, and pairs often reuse the nest in subsequent seasons.

Nesting Facts

Behavior

Tundra Swans can take off easily from land or water and fly with their necks extended straight out and their black legs trailing behind. Tundra Swans form life-long pairs that remain together year round. Pairs defend a breeding territory of open water and tundra up to a half-acre in size and chase off other swans, geese and Long-tailed Ducks. Such encounters can get physical, with the swans tackling and trampling an intruder or grabbing the tail during an aerial defense. When they’re not breeding Tundra Swans form large, gregarious flocks that travel, forage and roost together. Wintering birds foraging for clams in Chesapeake Bay often go head to head with Ring-billed, Herring, and Greater Black-Backed Gulls that swoop in to steal their prey. Back to top

Conservation

Tundra Swans are North America’s most numerous swan species. Partners in Flight estimates the global breeding population at 280,000 and rates them 10 out of 20 on the Continental Concern Score, indicating a species of low conservation concern. There is an annual, regulated hunting season for Tundra Swans in some states. Threats to these birds include lead poisoning by spent shot, fishing sinkers, and mine wastes deposited in sediments. Birds are also killed by diseases, including avian cholera, and a nematode (Sarconema eurycerca) may have caused Tundra Swan deaths in the Chesapeake Bay. Oil and gas drilling in Arctic breeding habitats and loss of wetlands at migratory stopover sites, particularly in the midwestern U.S. Prairie Pothole Region, are all potential threats to Tundra Swans.

Credits

Dunne, P. (2006). Pete Dunne's essential field guide companion. Houghton Mifflin Harcourt, New York, USA.

Limpert, R. J. and S. L. Earnst. (1994). Tundra Swan (Cygnus columbianus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Lutmerding, J. A. and A. S. Love. (2020). Longevity records of North American birds. Version 2020. Patuxent Wildlife Research Center, Bird Banding Laboratory 2020.

Partners in Flight. (2020). Avian Conservation Assessment Database, version 2020.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.

U.S. Fish and Wildlife Service. (2015). Waterfowl population status, 2015. Washington, DC: U.S. Department of the Interior.

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