Kauffman, M.J., Copeland, H.E., Cole, E., Cuzzocreo, M., Dewey, S., Fattebert, J., Gagnon, J., Gelzer, E., Graves, T.A., Hersey, K., Kaiser, R., Meacham, J., Merkle, J., Middleton, A., Nunez, T., Oates, B., Olson, D., Olson, L., Sawyer, H., Schroeder, C., Sprague, S., Steingisser, A., and Thonhoff, M., 2020, Ungulate Migrations of the Western United States, Volume 1: U.S. Geological Survey data release, https://doi.org/10.5066/P9O2YM6I.
Across the western U.S., many ungulate herds must migrate seasonally to access resources and avoid harsh winter conditions. Because these corridors traverse vast landscapes (i.e., up to 150 miles), they are increasingly threatened by roads, fencing, subdivisions and other development. Over the last decade, many new tracking studies have been conducted on migratory herds, and analytical methods have been developed that allow for population-level corridors and stopovers to be mapped and prioritized. In 2018, the U.S. Geological Survey assembled a Corridor Mapping Team to provide technical assistance to western states working to map bison, elk, moose, mule deer, and pronghorn corridors using existing GPS data. Based out of the Wyoming Cooperative Fish and Wildlife Research Unit, the team consists of federal scientists, university researchers, and biologists and analysts from participating state agencies. In its first year, the team has worked to develop a standardized analytical and computational methods and a workflow applicable to data sets typically collected by state agencies. In 2019, the team completed analyses necessary to map corridors, stopovers, and winter ranges in Arizona, Idaho, Nevada, Utah, and Wyoming. A total of 26 corridors, 16 migration routes, 25 stopovers, and 9 winter ranges, were mapped across these states and are included in this project. The Ungulate Migrations of the Western United States report and associated map archive provides the means for corridors to be taken into account by state and federal transportation officials, land and wildlife managers, planners, and other conservationists working to maintain big game corridors in the western states.