Pronghorn (Antilocapra americana) and greater sage-grouse (Centrocercus urophasianus) are two iconic species of the Northern Great Plains in western North America. Both undertake extensive migrations: pronghorn travel up to hundreds of kilometers across corridors in Wyoming, Montana, and Canada, and sage-grouse move in stepping-stone fashion along routes sometimes over 100 km long. However, agriculture and human infrastructure have largely fragmented the native shrublands and grasslands they use.
These migration pathways cross both private working lands and public multi-use lands, in addition to a network of core protected areas. Knowing not only which type of lands are used but also which lands might be important in the future can help direct conservation and management efforts and make them more effective.
A recent study radio-tracked 23 pronghorn and 18 sage-grouse that migrated at least once across the Milk River Basin in Montana and Saskatchewan to get more detailed information on their migratory routes. Both pronghorn and sage-grouse migrate at around the same time in spring and autumn (and occasionally winter), although pronghorns vary more in their timing and range.
Tracking data showed that all sage-grouse pathways and two-thirds of pronghorn pathways at least partly included three federally protected core areas (including one specifically designated for connectivity). However, most of the combined pathways for sage-grouse (89%) and pronghorn (59%) were composed of U.S. Bureau of Land Management land or private lands. Protected areas encompassed <5% of pathways for both species.
What does this mean for conservation and management of these two important grassland species? Maintaining current protections, such as protected area networks and conservation easements on private lands, will ensure that both mammalian and avian corridors persist and confer protection to each other. Limiting infrastructure that disrupts connectivity, such as fencing or gas and oil well drilling, will also ensure that migratory routes remain intact.
The greatest threat to conserving migration for both pronghorn and sage-grouse remains the potential for cultivating private grasslands. Practitioners can use this study to prioritize conservation easements and target parcels with high migratory value that have a high risk for future cultivation. In this way, the region can retain intact corridors that effectively conserve multiple taxa across a large, dynamic landscape.