Long-distance pronghorn migration in the Northern Rockies: A collaborative approach to species conservation

Background/Question/Methods

Long distance wildlife migration is at risk worldwide. In the Greater Yellowstone Ecosystem,  75% of migration routes for pronghorn and other migrants (including bison and elk) have been lost. These routes persisted for thousands of years, but have been cut off by human development. Threats to migration corridors are increasing across the Intermountain West, and the few remaining corridors are at risk. Maintaining these routes is an essential, but difficult, conservation challenge. Pronghorn make use of protected lands, like the Craters of the Moon National Monument and Preserve, managed by the National Park Service, but they move across a variety of landownerships and rely heavily on private land.

How do we sustain long distance migration in the face of land use change and development? We can only conserve these long distance routes if we know exactly where they are. The Lava Lake Institute documented the migration route of pronghorn that summer in the Pioneer Mountains.  We worked with partners at the Wildlife Conservation Society, Idaho Department of Fish and Game, and the Pioneers Alliance to study pronghorn migration. We placed Global Positioning System (GPS) collars on 10 female pronghorn to track their movements for one year.

Results/Conclusions

To the surprise of all involved, the majority of the collared pronghorn traveled from the Pioneer Mountains to the Little Lost River and Birch Creek in eastern Idaho. Prior to this study, this was an unknown migration route. The animals from the Pioneers join to form Idaho’s largest pronghorn herd on the winter range.

Fourteen does were collared in 2009. Data show variability in terms of summer and winter range use but strong fidelity to the very narrow migration route that extends from Lava Lake Ranch to Arco, passing through the Craters of the Moon National Monument. This segment of the migration route is wedged between the mountains and the highway and is as narrow as 200m.

Now that we know where the pronghorn migrate, our job is to protect that corridor. Many land stewards are involved with the persistence of this one population of pronghorn. Private landowners, the State of Idaho, Bureau of Land Management, Department of Energy, and the United States Forest Service all have lands that are used by this population of pronghorn. We are working with conservation organizations, landowners, and land management agencies to conserve this migration route and Idaho’s largest pronghorn herd in perpetuity.