Tundra Swan (Cygnus columbianus)

Photo by Scott Franke Tundra Swan by Scott Franke

Status/Protection

Population Information

Federal BBS information can be obtained at http://www.mbr-pwrc.usgs.gov/bbs/bbs.html by clicking on Trend Estimates and selecting the species in question. All estimates are for 1966-2005.

Life History

Habitat Selection

The Tundra Swan breeds on or near arctic tundra ponds, lakes, and sluggish rivers and occasionally near sheltered tidal waters, with nests located on islets, shorelines, heath tundra, hummocks in marshes, or tidal meadows. The eastern population of Tundra Swan spends half of the annual cycle migrating between the Atlantic Coast wintering areas and Arctic breeding areas. Although they use similar migratory pathways during spring and fall, there may be seasonal differences in staging areas used. During fall migration, Tundra Swans frequently stage at flooded sedge meadows, flooded river bottoms (J. March, pers. com.), large ponds, and wetlands containing extensive beds of sago pondweed and arrowhead as well as other wetland plants including wild celery, smartweed, bulrushes, and sedges. In the spring, wetlands are used to a lesser extent and agricultural fields, particularly those with corn, become more important (Petrie and Wilcox 2003).

Habitat Availability

Significant amounts of wetland habitats have been lost in the last century. Prior to Euro-American settlement, wetlands occupied an estimated four million hectares of the total fourteen million hectares of Wisconsin’s land area. Today, 53%, or 2.1 million hectares, of these wetland habitats remain (WDNR 1995).  Protection of these remaining wetlands and specific staging areas is critical to the conservation of Tundra Swans in Wisconsin. Major staging areas in Wisconsin occur along the Upper Mississippi River as well as flooded agricultural fields and wetlands from Buffalo County north to Douglas County in the west and Jefferson County north to Oconto County in the east. Suitability of staging or stopover habitat may be affected by several factors.  The presence of carp reduces water quality and suppresses the growth of submergent aquatic vegetation important to swans. Many inland lakes also have suffered from eutrophication, invasive plant species, fluctuating water levels, and increased sedimentation, resulting in a decline of food resources available to this species.

Population Concerns

Because of their remote northern breeding range, the Midwinter Waterfowl Inventory is the most reliable means to estimate Tundra Swan population size. During the 2006 inventory, 70,500 eastern population Tundra Swans were observed, 3% more than 2005. These estimates have decreased an average of 3% per year during
1997-2006 (USFWS 2006a). Aerial waterfowl survey data from the Upper Mississippi River pools consistently show concentrations of >15,000 staging Tundra Swans, with an eleven-year peak average of 25,172 (USFWS 2006b). The 2006 estimate of 52,070 individuals is the highest count since the aerial survey began in 1997.

Shooting may be the most significant mortality factor for post-fledging Tundra Swans with approximately 4,000 killed annually in regulated hunting and another 6,000-10,000 killed annually in unregulated hunting, which includes birds killed by hunters and others outside of sanctioned hunting seasons, as well as the take of native subsistence hunters in the Arctic. The hunting of Tundra Swans has received criticism due to the limited data available to guide harvest management (i.e., recruitment, productivity). Lead poisoning through the ingestion of spent shot and fishing sinkers and the loss and degradation of habitat also are significant concerns (Limpert and Earnst 1994).

Recommended Management

Conservation efforts should focus on preventing further wetland loss and degradation and restoring wetland complexes. Invasive species control, particularly carp, is critical for maintaining the suitability of existing wetlands. Partnerships between organizations dedicated to wetland conservation are essential to the long-term management and conservation of wetland complexes that provide staging habitat for this species (WDNR 2005). Sites that currently provide high quality forage should be prioritized for protection and managed as important staging areas.

Research Needs

Many aspects of Tundra Swan biology and ecology warrant further study, including length of incubation period, initial breeding age, and average lifespan. More study is needed on Tundra Swan time allocation between terrestrial and aquatic habitats during migration and fidelity to these staging sites (Limpert and Earnst 1994). Improved population monitoring and trend estimates would help guide harvest management.    

Information Sources

References

Contact Information

Kreitinger, K., Y. Steele and A. Paulios, editors. 2013.
The Wisconsin All-bird Conservation Plan, Version 2.0. Wisconsin Bird Conservation Initiative.
Wisconsin Department of Natural Resources. Madison, WI.

Website by J Davis Web Design