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Buffalo Field Office
Release Date: 02/18/11
Contacts: Lesley A. Collins    

Volunteers Count 290 Eagles During 2011 Midwinter Bald Eagle Survey

On the morning of January 8, 44 volunteers searched 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 and the U.S. Fish and Wildlife Service.

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A mature bald eagle taken by volunteers during the midwinter bald eagle survey on January 8, 2011.
A mature bald eagle taken by volunteers during the midwinter bald eagle survey on January 8, 2011.
Map of bald eagle sightings in the Powder River Basin during the 2011 midwinter bald eagle survey.
Map of bald eagle sightings in the Powder River Basin during the 2011 midwinter bald eagle survey.
Volunteers counted 200 bald eagles, 80 golden eagles, and 10 eagles of undetermined species on established survey routes along 1,340 miles of public roads. Sightings of several other raptor species were also reported, including rough-legged hawks and red-tailed hawks.

Eagle observations were most concentrated in the foothills along Interstate 90 between Sheridan and Buffalo. In these areas, road kill, fish, and waterfowl provide valuable winter forage, while trees offer roosting sites where the eagles can keep warm at night. Approximately 16 percent of the bald eagles observed were recorded along a route near Big Horn, Wyo. The abundance of upland game birds in the area may be why so many eagles prefer the area.

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 2010 surveys found 300, 162, 269, and 288 eagles, respectively. These survey totals vary due to the number of routes covered each year, but these totals are also influenced by weather and the availability of food sources including carrion, prairie dogs and rabbits.

This year, weather may have played an important role in eagle observations. “Visibility was hindered by poor light and precipitation conditions due to a storm system moving through the area over the weekend,” explains Darci Stafford, BLM wildlife technician. “It’s important to conduct the survey across the state on approximately the same day in order to get an accurate depiction of eagle distribution. We were worried we’d have to postpone the survey, but luckily the weather wasn’t as severe as originally forecasted.”

While hundreds of bald and golden eagles are seen in the Basin during the winter months, only a few stay year-round. Approximately 10 to 12 bald eagle pairs nest in the area. A greater number of golden eagles remain in the Powder River Basin to breed. The winter populations migrate north in March and April, returning to northern Canada and Alaska.

Resurveys were performed along 49 established routes, and nine additional routes were created to accommodate this year’s high volunteer turnout, bringing the total number of routes to 58 in 2011. “Volunteers are essential to the success of the midwinter survey,” said BLM Wildlife Technician Charlotte Darling. “Their participation helps wildlife managers monitor the Basin’s winter eagle population.”

The national midwinter bald eagle survey 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.

If you are interested in volunteering next year, or would like additional information, contact Charlotte Darling at (307) 684-1045 or Brad Rogers at 307-684-1046. For more information on the national program and its results, visit the U.S. Geological Survey Snake River Field Station website at

The BLM manages more than 245 million acres of public land, the most of any Federal agency. This land, known as the National System of Public Lands, is primarily located in 12 Western states, including Alaska. The BLM also administers 700 million acres of sub-surface mineral estate throughout the nation. The BLM's mission is to sustain the health, diversity, and productivity of America’s public lands for the use and enjoyment of present and future generations. In Fiscal Year 2015, the BLM generated $4.1 billion in receipts from activities occurring on public lands.

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Last updated: 02-18-2011