Volunteers counted 239 bald eagles, 91 golden eagles, and 24 eagles of undetermined species, on new and established survey routes along more than 1400 miles of public roads. Sightings of several other raptor species were also reported, the most common being rough-legged hawks and red-tailed hawks.
The Midwinter Bald Eagle survey has been conducted in the Powder River Basin since 2006, with 119 eagles counted in that year. The 2007 through 2013 surveys found 300, 162, 269, 288, 290, 304, and 310 eagles, respectively. These survey totals vary due to the number of routes covered in each year, but are also influenced by weather and the availability of food sources including carrion, prairie dogs, and rabbits.
Golden eagle observations were reduced slightly from 2013, while bald eagle numbers increased from last year. It is unknown why there was a shift in numbers seen in the Powder River Basin. The strong winds along some routes during this year’s survey may have caused golden eagles to stay closer to the ground, making them less visible from roadways. Bald eagles were primarily seen perched in trees and feeding on carrion. Additionally, a substantial number of eagles were counted along newly added survey routes.
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, and additional routes were added to include interested members of the public. Volunteer support makes the midwinter survey a success, and many volunteers, like Dick McCuistion, participate annually. “I’m a retired wildlife biologist, and it gives me satisfaction to see the bald eagle re-establishing itself and thriving in its Wyoming winter range. It’s nice to play a small part in this endeavor, and it’s fun to do. My wife and I look forward to participating every year,” said McCuistion.
While hundreds of bald and golden eagles are seen in the basin during the winter months, only a few stay year-round. Approximately ten to twelve bald eagle pairs 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 March and April, returning to northern 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 resource area, 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 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.
Other regions of the state participate in this yearly survey as well. Wildlife professionals from the BLM, USDA Forest Service, National Park Service, and U.S. Fish and Wildlife Service help coordinate local surveys in the following BLM resource management areas, national forests, and national parks: Casper, 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. The BLM Cody and Worland Field Offices have been participating in the survey since the late 1980’s, resulting in over 20 years of data that has been used in national population trend analyses.
If you are interested in volunteering next year, or would like additional information, contact Charlotte Darling at 307-684-1045 or Darci Stafford at 307-684-1144. For more information on the national program and its results visit the U.S. Army Corps of Engineers Bird Initiative website athttp://corpslakes.usace.army.mil/employees/bird/midwinter.cfm.