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 Cygnus buccinator    Richardson, 1831

Trumpeter Swan 


MN Status:

threatened
Federal Status:
none
CITES:
none
USFS:
yes


Group:

bird
Class:
Aves
Order:
Anseriformes
Family:
Anatidae
Habitats:

(Mouse over a habitat for definition)


Cygnus buccinator Cygnus buccinator Cygnus buccinator

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  Basis for Listing

The trumpeter swan was a widespread and relatively common breeder throughout the prairies and parkland regions of Minnesota until the mid-1800s. As central and western Minnesota were settled, this large, conspicuous bird quickly became over-hunted. When the first official species status review by the state was conducted in 1984, the last record of a wild breeding population in Minnesota was found to be from about 1885. As a result, the trumpeter swan was considered extirpated in the state. Subsequent recovery efforts have resulted in more than 2,400 free-flying birds in Minnesota. The species' breeding range is now expanding to the north and east, with trumpeter swans released in Minnesota documented in southwestern Ontario, and trumpeter swans released in Iowa nesting in Minnesota.

The state's initial trumpeter swan reintroduction goal of 15 breeding pairs and the revised goal of 500 individuals have both been met, but the long-term viability of the population is still unknown. Continued threats to the trumpeter swan population in Minnesota include loss or degradation of wetland habitat, lead poisioning, power lines collisions, and illegal shooting. It is estimated that lead poisoning from ingestion of lead shot and fish sinkers is responsible for more than half of the mortality of midwestern trumpeter swans (Gillette and Shea 1995). The trumpeter swan was listed as a threatened species in Minnesota in 1996.

  Description

The trumpeter swan is a large, white bird averaging 145-165 cm (4.8-5.4 ft.) in length, with a wingspan of 185-250 cm (6-8 ft.). Adults are white, and juveniles are light to medium gray. Adults have black bills and feet and juveniles have pink bills and feet that gradually turn black during their first year. There is some overlap in size between female trumpeter swans and male tundra swans (Cygnus columbianus), which are more common, making the two species difficult to distinguish in the field. The best cue is the trumpet-like call of the trumpeter swan.

  Habitat

During the breeding season, trumpeter swans select small ponds and lakes or bays on larger water bodies with extensive beds of cattails, bulrush, sedges, and/or horsetail. Ideal habitat includes about 100 m (328 ft.) of open water for take-off, stable levels of unpolluted, fresh water, emergent vegetation, low levels of human disturbance, and the presence of muskrat (Ondatra zibethicus) houses and American beaver (Castor canadensis) lodges for use as nesting platforms.

  Biology / Life History

Trumpeter swans in Minnesota generally only migrate to central or southern Minnesota or nearby states to overwinter, but some of the reintroduced birds have been documented wintering in scattered locations as far south as Arkansas, Kansas, Missouri, Oklahoma, and Texas. Trumpeter swans return to the breeding grounds as the spring thaw begins, typically in late March and early April. They usually mate for life and normally begin nesting when they are 3 or 4 years old. Breeding pairs often protect large (40 ha (99 ac.) or more) territories during the nesting period. They are intolerant of crowding and will drive out other intruding swans or predators. Both sexes contribute to construction of the nest, which may be on muskrat or beaver lodges, exposed hummocks, small islands, floating platforms, or on a foundation of marsh vegetation completely built by the swans. The female lays an average of 4-6 eggs in late April, which she incubates for up to 5 weeks. The male helps guard the nest. The young, or cygnets, stay in the nest for 1-2 days before following their parents to aquatic feeding grounds. They are typically able to fly at about 100 days of age. In July, while the cygnets are flightless, adult trumpeter swans lose their primary wing feathers and often stay hidden in the marsh with their young. By August, adult swans grow new primary wing feathers and start to fly again. The cygnets remain with their parents through their first winter and the return trip to the breeding area.

Adult trumpeter swans are mainly herbivorous, although they will occasionally feed on small crustaceans, fish, and fish eggs. Cygnets require an abundant supply of aquatic insects, crustaceans, and aquatic plants. Adults assist cygnets in feeding by treading the substrate and picking out food items (Mitchell 1994). Adults forage on the water surface or will tip-up and forage on roots and tubers on the bottom of a water body. Tip-up foraging can lead to the ingestion of lead shot and fishing sinkers, and the resulting lead poisoning has caused high mortality in many trumpeter swan populations.

  Conservation / Management

Lead poisoning is one of the greatest threats to trumpeter swans in Minnesota. Trumpeter swans ingest lead fishing sinkers and lead shots when they eat grit and forage for tubers and roots from marsh and lake bottoms. This threat increases during widespread drought and decreases during wet years. About 40% of Minnesota's trumpeter swan fatalities are caused by lead poisoning. Collisions with power lines is another major threat leading to trumpeter swan losses. Several power line companies are cooperating to install markers on problem wires, and such efforts should be encouraged and continued. Illegal shooting also poses a threat to Minnesota's trumpeter swans. Typically vandalism, not hunting, is the threat. However, it is important that hunters know the difference between swans and snow geese to prevent accidents. Education efforts to halt the shooting of trumpeter swans, whether due to malice or mistaken identity, are important and should continue.

Human activity in trumpeter swan habitat may also disrupt breeding pairs of swans. Jet skis, motor boats, collection of bait fish and leeches, and shoreline development impact water bodies and the beds of emergent vegetation where this species nests, and may cause reduced nesting success or abandonment of breeding attempts (Henson and Grant 1991). The posting of signs around trumpeter swan nesting areas may be necessary to prevent disturbance to breeding pairs.

  Conservation Efforts in Minnesota

In 1966, the Hennepin County Park Reserve District (now Three Rivers Park District) brought the first trumpeter swans back to Minnesota from Red Rock Lakes, Montana. However, initial breeding efforts were not successful. In 1969, they obtained an additional 40 trumpeter swans from Montana to establish a breeding flock. A few of the free-flying birds in this flock successfully nested outside of Hennepin County, marking the the first time trumpeter swans had nested in Minnesota in nearly 90 years. Subadult swans were first reintroduced into the Hennepin County Park Reserve District in 1978 and successful breeding was documented there in 1979. In 1982, a collaborative effort to accelerate swan restoration was undertaken by partners from state and federal agencies, Canadian provinces, universities, tribes, and The Trumpeter Swan Society. From 1982-1985, the Minnesota DNR's Nongame Wildlife Program acquired trumpeter swan eggs from wildlife refuges in Montana and South Dakota, zoos, and private propagators. From 1986-1988, eggs were collected from wild trumpeter swan populations in Alaska. The eggs were incubated and the hatchlings reared at the Carlos Avery Wildlife Management Area in Anoka County. In 1987, the Nongame Wildlife Program released 21 two-year-old trumpeter swans near the Tamarac National Wildlife Refuge in Becker County. Since then, more than 350 swans have been released in the state and Minnesota's trumpeter swan population now exceeds 2,400 birds (see video). Minnesota DNR biologists continue to conduct management and education efforts to ensure that a healthy population of this species remains in Minnesota. Efforts are also underway to encourage a percentage of Minnesota's swan population to migrate south of the state during the winter.

  References

Banko, W. E. 1960. The Trumpeter Swan: its history, habits, and population in the United States. North American Fauna 63. U.S. Fish and Wildlife Service, Washington, D.C. 214 pp.

Gillette, L. N., and R. Shea. 1995. An evaluation of Trumpeter Swan management today and a vision for the future. Pages 258-265 in K. G. Wadsworth and R. E. McCabe, editors. Proceedings of the 60th North American Wildlife Natural Resources Conference.

Henson, P., and T. A. Grant. 1991. The effects of human disturbance on Trumpeter Swan breeding behavior. Wildlife Society Bulletin 19:248-257.

Mitchell, C. D. 1994. Trumpeter Swan (Cygnus buccinator). Number 105 in A. Poole and F. Gill, editors. The birds of North America. The Birds of North America, Inc., Philadelphia, Pennsylvania.