Game & Fish surveys trumpeter swans
An adult trumpeter swan takes flight after being collared and released near Jackson. Photo by Mark Gocke, Wyoming Game & Fish.
Population numbers showing strong growth - increased 26% from 2014
by Wyoming Game and Fish
March 15, 2015
Wyoming Game and Fish Department nongame biologist, Susan Patla, recently conducted an annual winter survey for trumpeter swans, and other waterfowl, in the Pacific Flyway portion of western Wyoming. The annual aerial survey is coordinated with the U.S. Fish and Wildlife Service, and the states of Idaho and Montana, to obtain a count of all trumpeters in the Rocky Mountain population in the western United States. The majority of these swans winter in the Tri-state area of eastern Idaho, western Wyoming and southwestern Montana with small groups also found in Nevada and Oregon.
Overall, a total of 6,775 swans were counted in the Tri-state area, which is a 26% increase from 2014 when 5,368 birds were counted. Typically, over 90 percent (more than 5,000) of the wintering swans are migrants from interior Canada where nesting populations have shown strong growth for the past few decades.
This year, Patla counted a total of 931 swans in western Wyoming, or 14% of the total Tri-state wintering population. An additional 168 swans were counted in Yellowstone National Park (YNP). The numbers counted in Wyoming outside of YNP are almost identical to the previous five year average.
The total number of swans counted by drainage included: Snake River (515), Green River (211), and Salt River (119). Considering the year-round resident population of swans that nest in Wyoming (based on results of the fall survey), Canadian migrants likely comprised 86% of the swans wintering in the Snake River drainage and 39% of the Green River birds.
In most years, winter habitat for swans is very distinct from their summer habitat. However, given recent warm temperatures in February and March, swans have been found moving onto or near nesting areas that normally remain frozen until mid-March to early June. How this may affect available forage during the pre-nesting period is unknown. Little mortality has been documented this winter, but the Department requests that any dead swans found be reported immediately to the local Wyoming Game and Fish Department office.