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BUFFALO, Wyo. – Ninety-one volunteers spent the morning of Jan. 11, 2020, searching for bald and golden eagles across the Powder River Basin.  Their efforts were part of the nationwide Midwinter Bald Eagle Survey, coordinated locally by the Bureau of Land Management (BLM) Buffalo Field Office. Volunteers this year counted 464 eagles along more than 1,400 miles of public roads.   Sightings included 303 bald eagles, 127 golden eagles, and 34 eagles of undetermined species. Several other raptor species were also observed, the most common being rough-legged hawks.

The Midwinter Bald Eagle survey has been conducted in the Powder River Basin since 2006.  In recent years, the survey has found around 300 to 400 eagles, with a high of 547 in 2016.  Survey totals vary due to the number of routes covered in each year, but are also influenced by weather and visibility, as well as the availability of food sources including carrion, prairie dogs, and rabbits. Numbers of both golden and bald eagles decreased from 2019, likely due to mild weather and moderate snow cover in the region.  There were several sightings of large groups of eagles roosting together in cottonwood trees in riparian areas.  Volunteers also counted crows and ravens along each survey route.

The BLM relies heavily on area volunteers to complete the survey, and once again had a high level of participation.  All established survey routes were covered. “Volunteers range from young children to retirees, and their support is essential to the survey’s success,” notes BLM survey coordinator Charlotte Darling. “It is great to have so much public participation each year.  We truly appreciate our volunteers’ efforts and support.”

While hundreds of bald and golden eagles are seen in the Basin during the winter months, only a few of them nest in the area.  A greater number of golden eagles remain in the Powder River Basin to breed.  The additional winter populations migrate north in February, March and April, returning to the northern United States, Canada and Alaska. The information gathered by the survey is used by wildlife researchers and managers nationwide, but is also valuable on the local level. The data collected helps the BLM to determine important habitats in the Buffalo Field Office, which consists of Campbell, Johnson, and Sheridan counties.

The national Midwinter Bald Eagle Survey effort began in 1979 as an effort to identify wintering habitat and develop a total population index for the struggling eagle population in the lower 48 states.  Collecting eagle data over the long-term has allowed analyses of population trends that help to monitor the health of the species as a whole.  A 25-year trend analysis paper covering the years 1986-2010 has been accepted for publication in The Journal of Raptor Research and was published in September 2015.

Other regions of the state also participate in this annual survey.  Wildlife professionals from the BLM, U.S. Forest Service, National Park Service, and U.S. Fish and Wildlife Service help coordinate local surveys in Cody, Kemmerer, Lander, Newcastle, Pinedale, Rawlins, Rock Springs, and Worland BLM Field Offices, Bridger-Teton National Forest, Medicine Bow National Forest, Grand Teton National Park, and Yellowstone National Park.

If you are interested in volunteering next year, or would like additional information, contact Charlotte Darling at 307-684-1045.  For more information on the national program and its results visit the U.S. Army Corps of Engineers Bird Initiative website at https://corpslakes.erdc.dren.mil/employees/bird/midwinter.cfm.