The Trumpeter Swan
 Swan pair with day-old cygnet |
Rocky Mountain Trumpeter Swan
Range Expansion Program
Pacific Flyway Council and U.S. Fish and Wildlife Service
Original text by Ruth Shea, Idaho
State University.
Revisions by Linda Rawley, Wildlife Specialist, Utah Division of Wildlife Resources
History of Rocky Mountain Trumpeter Swans
Once abundant and widespread throughout much of North America, trumpeter swans were nearly extinct by 1900. Both their numbers and their distribution were severely reduced by subsistence hunting, the commercial plumage trade, and habitat changes. The only trumpeters that survived were those that lived year-round in remote areas or whose traditional migration patterns avoided areas of human settlement.
Small flocks persisted only in Alaska and remote habitats of the Rocky Mountains. In the lower 48 states and Canada, the last remaining 200 Rocky Mountain trumpeters survived by wintering in the frigid wilderness in the Yellowstone Region where warm springs kept small areas of water ice-free regardless of winter severity. Although winter habitat was meager and limited by ice formation, the swans found security.
Rocky Mountain trumpeters that wintered in the Yellowstone Region included some that were year-round residents and others that migrated north each spring to Canadian nesting areas. Virtually all of the trumpeters that migrated south to milder wintering areas had died by 1930 and the use of those traditional migration routes was lost.
Although among the rarest of our
native waterfowl, decades of conservation efforts have helped the Rocky Mountain
trumpeters increase to about 3,000 birds. Despite this promising growth in numbers, their
winter distribution remains restricted primarily to several locations in the tri-state
area of Montana, Wyoming, and Idaho.
Historic migrations to winter habitats further south have not yet been restored. As a result, each fall the growing flocks of Rocky Mountain trumpeters from Canada and the tri-state area return to their primary wintering area, the rivers of the Yellowstone Region.
The Problem
In eastern Idaho, this lack of dispersal southward has created a severe "bottleneck" as increasing numbers of trumpeters arrive from Canadian nesting areas to spend the winter within Harriman State Park on the Henry's Fork of the Snake River in eastern Idaho. At this site, which receives the greatest amount of swan use, the aquatic plants can no longer provide enough winter food to support the increasing flocks of swans, Canada geese, and ducks.
During recent mild winters hundreds of trumpeters have moved into other eastern Idaho sites—the Teton River, South Fork of the Snake River, and the lower Henry's Fork. When a severe winter strikes this region, much of this area will freeze. Mortality will likely be high among swans that attempt to remain at these sites.
Despite the promising increase of Rocky Mountain trumpeters, until we restore their migrations and help them return to more suitable wintering areas, their recovery will remain questionable.
Why Haven’t the Swans Moved South?
In addition to the loss of historic migrations, for almost 60 years the last remaining trumpeters were encouraged to winter in the Yellowstone Region. Although some attempted to explore and migrate further south, they had little success.
From 1935-1992, the trumpeters were fed grain during winter at Red Rock Lakes National Wildlife Refuge, 20 miles northwest of Harriman State Park. Large sanctuaries in Yellowstone and Grand Teton National Parks and at Harriman State Park also protected the swans from human disturbance. While artificial feeding and sanctuaries saved the population from extinction, they discouraged southward migration which is essential to long-term recovery. Artificial feeding at Red Rock Lakes ceased in 1992.
Current Management Efforts
Since 1988, over 1,300 trumpeter swans have been captured at Harriman State Park and Red Rock Lakes National Wildlife Refuge and transplanted to new habitats in Oregon, southern Idaho, and Wyoming. Several were also moved to Utah.
Transplanted swans were neck collared and dyed, and closely monitored through a network of observers.
The disturbance from trapping and occasional planned disturbance has reduced the number of swans at high risk sites in the vicinity of Harriman State Park. Reduced swan use at Harriman has allowed some increase of aquatic plants which has improved habitat for both fish and waterfowl.
Transplanted swans have been sighted in all western states and are slowly increasing use of other wintering sites as far west as Oregon and California. Serious problems remain in eastern Idaho, however, as wintering swans continue to increase.
Up through 1995, biologists attempted to establish trumpeter swan migrations that would avoid tundra swan hunting areas. This was done to minimize the potential for a legal tundra swan hunter to accidentally harvest a trumpeter.
Beginning
in 1994, tundra swan hunting regulations in Utah, Nevada, and Montana were changed to
reduce the potential harvest of trumpeters, and to protect legal tundra swan hunters from
legal action should they accidentally harvest a trumpeter. These changes enabled
biologists to transplant trumpeters into areas where they have a greater potential to
follow migrating tundra swans to southern wintering areas where food resources are
plentiful.
Unless the present "bottleneck" can be opened, trumpeters from across western Canada will continue to end their southward migration in the tri-state area. They must either be persuaded to migrate through this region and continue south or they will exceed the carrying capacity of winter habitat and die there. The tri-state’s local nesting swans, forced to share marginal sites with the growing Canadian flocks, will also be at risk.
Management Options
Management options are limited. Substantial mortality is likely unavoidable; the problem has developed over decades and will not be easily solved. Additional transplants may help create use of other wintering areas but cannot possibly remove enough swans from eastern Idaho. Artificial feeding can no longer meet the needs of the increasing flocks. Feeding would concentrate swans as well as ducks and geese, creating a high risk of disease and discouraging any migration.
A well-organized program to systematically haze trumpeters offers another option to increase the number of birds that continue southward, but success is by no means a certainty. Fall hazing efforts will be increased; various techniques will be tried, and results will be closely monitored. Best results are likely if hazing occurs during the peak migration while the swans are still in good condition. To keep swans moving, hazing must be frequent and consistent over a broad area.
Regardless of hazing intensity and translocation efforts, some swans will likely remain in eastern Idaho and face harsh winters and limited food supplies. Our goal is to disperse as many swans as possible from the area.
Long-term population security will depend upon the survival of trumpeters in a wide variety of wintering sites. Currently, the Pacific Flyway Council is emphasizing monitoring over translocation in order to better understand the migration corridors used by the Rocky Mountain trumpeter swans.
For more information on Rocky Mountain trumpeter swans, contact the Idaho Department of Fish and Game, Utah Division of Wildlife Resources, or U.S. Fish and Wildlife Service.
| IDAHO | Headquarters Panhandle Clearwater Southwest McCall Magic Valley Southeast Region Upper Snake Region Salmon Region |
(208) 334-3700 (208) 769-1414 (208) 799-5010 (208) 465-8456 (208) 634-8137 (208) 324-4359 (208) 232-4703 (208) 525-7290 (208) 756-2271 |
| USFWS | Pocatello Office | (208) 237-6616 |
| UTAH | Headquarters | (801) 538-4700 |
Please report marked swans to:
For
Utah sightings: For sightings
from the Rocky |
 |
When reporting a marked swan, please note the precise location and date of sighting, the color of neck-collar and color and location of any dye, and if available, the location and order of the letters and numbers on the neck-collar.
