Ungulate migrations are important for ecosystems but are at risk. In the western United States, the integrity of ungulate migrations is of concern among rapid expansion of transportation infrastructure, canals, fences, pipelines, energy extraction, and housing development. These anthropogenic features create barriers which often overlap with ungulate habitat, causing loss and fragmentation of migration corridors and seasonal range. The importance of migrations for sustained ungulate populations has stressed the urgency for widespread migration mapping and assessment of conservation opportunities.
In 2018, the U.S. Geological Survey assembled a Corridor Mapping Team (CMT) to provide technical assistance to western states working to map bison, elk, moose, mule deer, and pronghorn migrations using Global Positioning System (GPS) tracking data. Led by the Wyoming Cooperative Fish and Wildlife Research Unit, the CMT consists of federal scientists, university researchers, and biologists from participating state agencies and tribal governments. The CMT has developed standardized analytical and computational methods applicable to GPS tracking datasets. These analytical methods allow for population-level migration corridors and stopovers to be mapped. In 2020, the team released the report titled ‘Ungulate migrations of the western United States, Volume I’ which included maps of corridors, stopovers, routes and winter ranges in Arizona, Idaho, Nevada, Utah, and Wyoming.
Applying these migration maps, state and federal transportation officials, land and wildlife managers, planners, and other conservationists can consider conservation opportunities using a prioritized and focused approach. For example, the Arizona Game and Fish Department (AZGFD) and partners have been using the mapped migration corridors to understand where they intersect with high volume roads through a statewide assessment of Transportation and Wildlife-Vehicle Collision hotspots. Additionally, they are identifying areas in need of livestock fence inventory and modification to create better landscape permeability. AZGFD has also used the migration maps to help decide where to locate over 9,000 acres of restoration projects on winter range and stopover habitat.
Linking GPS tracking data to migration maps is a key step in conservation planning, especially when financial resources for conservation projects are limited. An emphasis on migration mapping through collaborative efforts will help ensure that migratory ungulate populations continue to be taken into consideration.