We use the best available science to ensure the survival of Montana's birds and other wildlife.
The Golden Eagle Migration Survey (GEMS) is a collaborative, science-based effort to monitor the autumn migration of Golden Eagles and other raptors along the Big Belt Mountains of Montana.
The Big Belts is a 75-mile long, northwest-southeast trending ridgeline managed by the Helena, Lewis and Clark National Forest. The range is bordered to the west by Canyon Ferry Lake, a 35,181-acre artificial reservoir created by the damming of the Upper Missouri River. To the east of the Big Belts lies Shields Valley and farther east is another string of northwest-southeast trending mountain ranges. Following the Big Belt Mountains toward the south, southeast leads to the Bridger Mountains, where many of the raptors migrating through the Big Belt Mountains also likely pass. The Big Belts are part of a network of ten migration survey sites in western Montana north through Alberta.
The Big Belt Mountains were first recognized as a significant Golden Eagle migration flyway by Missoula-based Rob Domenech, with Raptor View Research Institute (RVRI) in 2007. Exploratory migration counts were conducted by Steve Hoffman, founder of HawkWatch International and former Executive Director of Montana Audubon, in October of 2014. Since 2015, Montana Audubon has supported annual migration surveys at Duck Creek Pass Strong southwesterly winds typically prevail across the crest of the Big Belts. These consistent winds, combined with the Big Belts’ steep west-facing slopes, generate powerful orographic lift, thus providing ideal flying conditions for migrating raptors. The ‘lake-effect’ of Canyon Ferry Reservoir may enhance the consistency and speed of these westerly winds over the Big Belts. These factors, along with the prominent “leading line” created by the Rocky Mountain Front (which extends to the north well into Canada) make the southern end of the Big Belts a profoundly significant concentration point for migrating raptors in autumn. Thousands of Golden Eagles migrate south past the site each fall, with some October days seeing over three-hundred birds pass during survey hours.
Learning how to identify raptors takes time, but that is why we support educational opportunities at the site each year. Please contact Amy Seaman ([email protected]) for more information about this project, and please check out our Big Belts site reports: 2016, 2017, 2018 and a short wrap-up, 2019.
Come to the Bridger Raptor Festival, an annual event held in and around Bozeman! The festival, which is free to the public, centers around a raptor migration count of the largest known Golden Eagle migration in the United States which takes place at the Bridger Bowl ski area in the Gallatin National Forest just north of Bozeman. The event is the first weekend in October, and we will be there to share our raptor identification expertise with the surrounding community.