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TAXON: Tundra Swan, Cygnus columbianus

Image of Tundra Swan, photo by C. Ely

Justification: A segment of the breeding population of Tundra swans is believed to breed in eastern Asia and winter in North America, and could potentially carry Asian H5N1 from Asia to North America.

Background:

Tundra swans are polytypic, with three recognized subspecies: the nominate form (Whistling Swan) in North America, C. c. bewickii in Western Eurasia and C. c. jankowski in eastern Asia. The validity of jankowski has been questioned because of the lack of any clear division between this and bewickii. The nominate form is thought to breed as far west as eastern Chukotka. In Alaska, birds breeding on the North Slope migrate eastward during autumn and winter in the Atlantic Flyway (Limpert et al. 1991, Limpert and Earnst 1994), whereas birds breeding in western Alaska migrate down the Pacific Flyway (Ely et al. 1998). A small non-migratory population on the lower Alaska Peninsula (Izembek NWR, Dau and Sarvis 2002) and Unimak Island nearly doubles in size in winter to approximately 600 birds. Extensive marking to the north along the Alaska Peninsula and less so elsewhere in Alaska has not indicated the source of the additional swans. It is not known what Alaskan population of Tundra swans is most likely to migrate to Asia. The Tundra swan is one of the lowest ranked waterfowl to make the final list of 26 species of concern for Asian H5N1 transmission in the National Plan, primarily because there is only weak evidence supporting their presence in eastern Asia. It will also be very hard to identify the likely small fraction of birds migrating to or from Asia, so obtaining samples from birds that are most likely exposed to Asian H5N1 will be very difficult. In addition, large numbers (> 30) of Tundra swans have rarely been captured and banded in Alaska. It is unknown where the large concentrations of non-breeding Tundra swans that use the outer Yukon-Kuskokwim Delta (YKD) in early July go to molt. Swans have, however, been one of the primary species groups affected by Asian H5N1 in Asia and Eastern Europe, and Tundra swans have been identified as a high priority species in the Pacific Flyway.

Ranking Score: 11.0

Methods:

No. of samples: A sample of > 200 birds will be necessary to detect the virus. Attaining this goal might prove quite difficult.
Sampling locations: It is believed that Asian-bound, or returning Tundra swans will migrate over the Seward Peninsula, Kotzebue Sound and St. Lawrence Island, so sampling efforts will be concentrated in these areas. Additional birds may be captured on the Yukon Delta, Alaska Peninsula, or North Slope of Alaska.
Sampling timeframe: Late Spring and early summer (May-June) for swans migrating to Asia, July for molting flocks on the YKD and North Slope, and August-September for swans returning from Asia.
Sample demographics: All age and sex classes will be sampled given the difficulty in obtaining samples.
Methods of capture: Spring and autumn migrants will be sampled via subsistence harvest. Molting birds will be live-captured using aircraft and boats.
Other targeted species: Other Asian-bound and returning migrants will be sampled in the subsistence harvest on St. Lawrence Island and the Seward Peninsula.

Principal Investigator(s):

U.S. Fish and Wildlife Service
Migratory Bird Management (subsistence harvest)
Contact: Deborah Rocque

Selawik NWR (molting flocks is July)
Contact: Tina Moran

Yukon Delta NWR (molting flocks in July)
Contact: Fred Broerman

Kawerak Corporation
Contact: Austin Ahmasik

Literature Cited:

Ely, C. R., D. Douglas, A. Fowler, C. Babcock, D. V. Derksen, and Y. Takekawa. 1998. Migration behavior of Tundra Swans from the Yukon-Kuskokwim Delta, Alaska. Wilson Bulletin 109:679-692.

Evans, M. E., and W. J. Sladen. A comparative analysis of the bill markings of Whistling and Bewick’s Swans and out-of-range occurrences of the two taxa. Auk 97:697-703.

Limpert, R. J., W. J. Sladen, and H. A. Allen, Jr. 1991. Winter distribution of Tundra Swans Cygnus columbianus columbianus breeding in Alaska and western Canadain Arctic. Wildfowl Suppl. No.1:78-83.

Limpert, R. J. and S. L. Earnst. 1994. Tundra Swan (Cygnus columbianus). In The Birds of North America, No. 89 (A. Poole and F. Gill, Eds.). Philadelphia: The Academy of Natural Sciences; Washington, D.C.: The American Ornithologists’ Union.

Ogilvie, M. A. 1972. Distribution, numbers and migration. Pp. 30-55 In The Swans. (P. Scott, ed.). Houghton Mifflin Co., Boston, Masssachusetts.

Asian H5N1 ranking criteria for Tundra Swan, Cygnus columbianus.

Total of partial
contact with Asia1
Contact with
known "hot spot"2
Habitat used in
Asia3
Pop. in Alaska4
Can samples be
obtained?
Score
1.0
1.0
4.0
3.0
2.0
11.0
Unknown numbers breed in e. Chukotka; may be associated with Pacific flyway
No known use of AI-infected areas
Nests coastal tundra; migration and nonbreeding in coastal habitats
Approximately 150,000 summer in Alaska
Could be difficult to obtain target number
 

 

Distribution Map:
Distribution map of Tundra Swan

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Page Last Modified: August 08 2014 08:44:52.