The Pioneers-Craters landscape is home to a diverse array of wide-ranging and migratory wildlife species such as pronghorn, sage-grouse, mule deer, and elk as well as large carnivores including wolves, mountain lions, and black bears. The landscape is also home to mountain goats, wolverines and a large number of bird species. The abundance and diversity of wildlife are supported by the diversity of the landscape’s elevations which range from 4,000 feet to 12,000 feet, long free-flowing rivers and streams and their associated riparian habitats, extensive ungulate winter ranges, and the relatively unfragmented and undeveloped character of the land. The presence of abundant wildlife is one of the key values that people of all backgrounds most treasure about the region. Hunting remains a cultural cornerstone of the region and the opportunity to see wildlife in a natural setting is one of the assets most frequently cited as important to them by residents and visitors alike. In order to document the status of wildlife populations and to guide our conservation and stewardship work, the Pioneers Alliance has conducted a number of wildlife science projects focused on pronghorn migration, mule deer migration and greater sage-grouse. We chose to focus on documenting migration routes because long distance wildlife migration is increasingly at risk throughout the world. In the Greater Yellowstone Ecosystem, an area known for protected lands, approximately 75% of migration routes for pronghorn and other long distance migrants (including bison and elk) have been lost. These routes had previously persisted for thousands of years, but have been cut off by human development. Threats to wildlife 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 and other wildlife 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 the landscape and rely heavily on private land.
The pronghorn migration study was initiated in 2008 with the goal of identifying the migration route from the summer range in the Pioneer foothills to the winter range (the location of which had not been scientifically documented at the time the study was initiated). Ten pronghorn does were captured and collared with a global positioning system collar designed to document their movements for one year, with an emphasis on their movements during the migration period. The collars were programmed to release in late summer 2009 after the animals had traveled to the winter range and back. The study showed that the pronghorn traveled farther and in a different direction than we had expected. Rather than heading south, the animals headed east to the Big Lost River drainage where they joined one of the largest winter ranges for pronghorn. The average distance traveled one way was over 80 miles. Multiple migration trajectories were identified in subsequent studies, including migration routes into Montana across the Continental Divide. Our work documenting the pronghorn migration route catalyzed work by the National Park Service at Craters of the Moon to inventory and then modify or remove fencing that might pose an obstacle to migrating pronghorn. The Pioneers Alliance is working to expand this work onto additional federal and private lands in the area. The pronghorn migration study has been conducted in partnership with a diverse group including the Lava Lake Institute for Science and Conservation, the Wildlife Conservation Society, the Idaho Department of Fish and Game, the Craters of the Moon National Monument and Preserve, The Nature Conservancy, The Conservation Fund, The Wood River Land Trust and local ranchers. Additional information about this study, including a full list of partners and a video of the migration route can be found on the Lava Lake Institute website.
Mule Deer Migration
After learning about the power of documenting the pronghorn migration route with GPS collars, we wanted to learn more about other wildlife species that use the Pioneers-Craters landscape. By partnering with the Idaho Department of Fish and Game, we have been able to learn more about the migration routes of mule deer in the landscape. We have been amazed to see that mule deer, somewhat like pronghorn, do not migrate on a north-south pathway but, rather, appear to be migrating east-west across the mountains and foothills of the Pioneers to reach the snow shadow on the east side of the range in the Big Lost River valley.
Greater sage-grouse are also a migratory species. Sage-grouse can travel up to 45 miles between seasonal ranges and can occupy up to 1000 mi2 annually. Despite these long distance movements, sage grouse return to the same place every year for mating and nesting. Sage grouse are also a “Candidate” for listing under the federal Endangered Species Act protection due to a severe decline in available breeding habitat.
We have been working to refine the habitat maps for sage-grouse in the landscape and to document sage grouse leks, or breeding grounds. Activity on leks is used as a key metric for the health of sage-grouse in a given area so we wanted to learn more about sage grouse leks in the landscape. The Pioneer Mountain foothills was an area that had not previously been surveyed for sage grouse leks due to difficult access during the spring season. Multiple new leks have been identified during the surveys, further documenting the importance of this landscape for sage-grouse. In addition, we know that there is fall and winter use by sage-grouse of high ridgelines of mountains overlooking Craters of the Moon.