Rare Species Guide

  Basis for Listing

The Trumpeter Swan (Cygnus buccinator) was a widespread and relatively common breeder throughout the prairies and parkland regions of Minnesota (Prairie Parkland and Tallgrass Aspen Parkland provinces) until the mid-1800s. As central and western Minnesota was settled, this large conspicuous bird quickly became over-hunted. The last record of a wild breeding population in Minnesota is from about 1885, and the Trumpeter Swan was declared extirpated in the state by the mid 1900s. Minnesota’s swan reintroduction efforts began in 1966, were expanded in the 1980s, and continued through 2012. The Trumpeter Swan population and breeding range increased slowly at first, but has continued to build to the point where they currently nest throughout much of Minnesota. 

The state's initial Trumpeter Swan reintroduction goal of 15 breeding pairs and the revised goal of 500 individuals have both been met and surpassed, 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 poisoning, power line collisions, and illegal shooting. It is estimated that lead poisoning from the ingestion of lead shot and fish sinkers is responsible for more than half the mortality of Trumpeter Swans in the Midwest (Gillette and Shea 1995).  Hence, the Trumpeter Swan was listed as a threatened species in Minnesota in 1996. Although the population recovery has far exceeded expectations, in 2013, due to continued threats, the Trumpeter Swan was included on Minnesota’s List of Endangered and Threatened Species List, with the status of special concern.

  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), making the two species difficult to distinguish in the field during spring and fall, when Tundra Swans are migrating through the state.  The best cue, from a distance, is the trumpet-like call of the Trumpeter Swan. Seen up close, the Trumpeter Swan's bill is solidly black; whereas, the Tundra Swan's bill often has a yellow mark in front of its eye. In addition, when viewed head-on, the Trumpeter Swan's forehead comes to a sharp point as it meets the top of the bill; this same area is rounded on the Tundra Swan.

  Habitat

During the breeding season, Trumpeter Swans select small ponds and lakes or bays on larger water bodies with extensive beds of emergent vegetation such as cattails, bulrushes, and sedges (marsh). Ideal habitat includes about 100 m (328 ft.) of open water for take-off, stable levels of unpolluted fresh water, emergent marsh vegetation, low levels of human disturbance, and the presence of Muskrat (Ondatra zibethicus) houses and North 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 their breeding grounds as the spring thaw begins, typically in late March and early April. They usually mate for life, but will find another mate if their mate is lost. They 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 and may drive out intruding swans, other birds, and mammals. 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 built completely by the swans themselves. The female lays an average of 4-6 eggs in late April that she incubates for up to 5 weeks. The male helps guard the nest. The young, called '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 until the return trip to their breeding area. 

Adult Trumpeter Swans are mainly herbivorous, though 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 shot when they eat grit or forage for tubers and roots from marsh and lake bottoms. This threat increases during widespread drought, when lead in the sediment is more easily reached by swans, 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 have installed markers on problem lines, and such efforts should be encouraged and continued. Illegal shooting also poses a threat to Minnesota's Trumpeter Swans, with poaching, rather than hunting, the primary threat. That said, 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).

  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 unsuccessful. 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 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 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. From 1987 to the late 1990s, more than 350 swans were released in the state, and Minnesota's Trumpeter Swan population exceeded 2,400 birds. In 2022, the Minnesota Breeding Trumpeter Swan Survey (Herberg and Rettler) estimated the statewide population at 51,860 swans (90% Confidence Interval: 45,530 – 58,190). The full report of this survey includes references to additional statewide, regional, and national population trend information and resources.

  Authors/Revisions

Steven P. Stucker (MNDNR), 2018

(Note: all content ©MNDNR)

  References and Additional Information

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.

Henderson, C. 2017. Visions of Swans. Minnesota Conservation Volunteer. Minnesota Department of Natural Resources, Saint Paul. March-April 2017.

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

Herberg, A., and S. Rettler. 2022. Minnesota breeding trumpeter swan survey 2022: final performance report. Minnesota Department of Natural Resources. St. Paul. 22pp.

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.