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The Mountain-Prairie Region


U.S. Fish and Wildlife Service
134 Union Boulevard
Lakewood, Colorado 80228

January 28, 2003

Contacts: Chuck Davis 303-236-7400 ext 35
John Cornely 303-236-8155 ext 259 (available 1/29/03)
Sharon Rose 303-236-7917 ext 415

U. S. Fish and Wildlife Service Finds Trumpeter Swan Flock
not an Endangered Population

The U.S. Fish and Wildlife Service announced today that a petition seeking Endangered Species Act protection for trumpeter swans in the Yellowstone ecosystem presents insufficient evidence to establish that they should be listed as threatened or endangered under the Act.

After an evaluation of available information, the Service determined that the petition, filed by the Biodiversity Legal Foundation and the Fund for Animals, does not contain substantial information to proceed with a more in-depth status review. The petition asked the Service to declare the "tri-state flock" of trumpeter swans near Yellowstone National Park in Wyoming, Montana and Idaho as a "distinct population segment" under the Act.

The Service’s Distinct Vertebrate Population Segment Policy, published in 1996, stipulates that a population segment must be both discrete and significant to qualify for listing under the Endangered Species Act. As such, a species’ physical, physiological, ecological and behavioral characteristics must be markedly different from other members of the same species.

The Service’s finding indicates that the tri-state flock of trumpeter swans –a group of largely non-migratory swans that breed and winter in and around Yellowstone National Park, in Wyoming, Montana and Idaho – interacts with and is not significantly different from the rest of the Rocky Mountain population, which inhabits areas in and near the Rocky Mountains in the United States and Canada. For example, while most swans in the tri-state area do not migrate north to Canada in the spring, trumpeter swans from the Interior Canadian flock do winter together with the tri-state flock in the Yellowstone ecosystem. Also, current banding and marking information indicates that there may be some dispersal of swans from the tri-state flock to other parts of North America.

"The trumpeter swan represents one of the great success stories in migratory bird conservation, with populations across the continent reaching record highs in recent years. The Rocky Mountain population, which includes the tri-state birds, has experienced an average annual growth rate of 5 percent over the past 30 years. There is no evidence to suggest that the tri-state flock should be evaluated separately from that population," said Ralph Morgenweck, director of the Service’s Mountain-Prairie Region.

Information provided for this petition finding also indicates that there is essentially no difference in the way trumpeter swans are managed in Canada and the United States. The species is protected in both countries under the Migratory Bird Treaty Act, and management plans and conservation actions are developed and implemented cooperatively by the United States and Canada through international flyway councils.

The population of trumpeter swans in North America has grown from less than 4,000 birds in 1968 to nearly 24,000 birds in 2000. This represents an average annual growth rate of 5.9 percent. The Rocky Mountain population of trumpeter swans, which includes the tri-state birds, increased from approximately 800 birds in 1968 to more than 3,600 in 2000.

The Service was petitioned to list the tri-state flock in August 2000. In October 2000, the petitioners filed suit to halt a legal tundra swan hunt in Utah, Montana and Nevada, arguing that the hunt jeopardized trumpeter swan populations in the area because of the difficulty of distinguishing between the two species under field conditions.

The Service has modified the limited take and restricted hunting seasons on tundra swans in those areas to give added protection to trumpeters. Swan harvests in Utah and Nevada continue to be monitored, with the hunting season immediately closed if the states’ limited quota of trumpeter swans is reached.

The Service allowed these hunts to continue after evaluating population and harvest data during a five-year experimental swan hunt between 1995 and 1999. Despite the killing of approximately 38 trumpeter swans mistaken by hunters for tundra swans over the five-year period, the Rocky Mountain population of trumpeter swans grew by an average of six percent per year during that period, suggesting that the limited hunt did not have a significant impact on the population.

The trumpeter swan (Cygnus buccinator) is the largest native waterfowl species in North America, but tundra swans are nearly as large. Both have white plumage and black bills. The legal limit for the take of trumpeters is set at 10 in Utah and five in Nevada during permit-only swan-hunting seasons. If the limit is reached, the swan hunting season is closed immediately in that state. This assures that the accidental harvest of trumpeter swans remains minimal. Trumpeters taken in those two states come from the more abundant Interior Canada flock and from the tri-state area. Neither Canada nor the United States establishes hunting seasons specifically for the trumpeter swan.

The Service’s petition finding is published in today’s Federal Register. Copies and background material can be downloaded from the Service's web site at Requests for copies of the final rule and economic analysis should be submitted to the Regional Director (ES), U.S. Fish and Wildlife Service, P.O. Box 25486 DFC, Denver, Colorado 80225-0486.

The U.S. Fish and Wildlife Service is the principal Federal agency responsible for conserving, protecting and enhancing fish, wildlife and plants and their habitats for the continuing benefit of the American people. The Service manages the 95-million-acre National Wildlife Refuge System, which encompasses 540 national wildlife refuges, thousands of small wetlands and other special management areas. It also operates 70 national fish hatcheries, 64 fishery resource offices and 78 ecological services field stations. The agency enforces Federal wildlife laws, administers the Endangered Species Act, manages migratory bird populations, restores nationally significant fisheries, conserves and restores wildlife habitat such as wetlands, and helps foreign governments with their conservation efforts. It also oversees the Federal Aid program that distributes hundreds of millions of dollars in excise taxes on fishing and hunting equipment to state fish and wildlife agencies. For more information about the U.S. Fish and Wildlife Service, visit our home page at


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