Wildlife Migration Routes Key to Sustaining Big Game Herds in Wyoming

Wildlife-friendly fencing, seasonal restrictions on certain human activities, and prescribed burning to foster new growth of certain plants are among the strategies that could help big game thrive in western Wyoming’s Bridger-Teton National Forest, according to a new report.

Commissioned by The Pew Charitable Trusts for the Wyoming Wildlife Federation, the Theodore Roosevelt Conservation Partnership, and Backcountry Hunters & Anglers, the first-of-its-kind report profiles big game migration information for the region and connects this spatial data with forest management considerations and needs.

The report—“Conservation Assessment of Big Game Migration on Wyoming’s Bridger-Teton National Forest”—was written by wildlife biologist Veronica Yovovich, Josh Gage of the data visualization firm GageCarto, and Nicholas Fox of Fox Geoscience. It consolidates movement data for 16 big game herds—five elk, nine mule deer, and two moose—and includes maps of crucial seasonal range and habitat connectivity data for those three species, and for bighorn sheep, pronghorn, and Rocky Mountain goat. Bridger-Teton National Forest makes up much of the southern extent of the Greater Yellowstone Ecosystem, which is the largest remaining intact ecosystem in the Lower 48.

Wildlife-friendly fences that keep domestic animals where they’re supposed to be while allowing wildlife to pass through could help the herds, according to the report. Another possible strategy involves restricting certain activities—vehicle travel or recreational pursuits, for example—at certain times and places, to reduce noise or movement that might frighten migrating wildlife. The report also suggested that prescribed burning could be helpful by increasing the growth of flowering plants, grasses, and shrubs that the animals prefer.

Gregory Nickerson, Wyoming Migration Initiative/University of Wyoming

Scientists consider migration to be an important survival strategy for big game herds in harsh climates such as Wyoming’s. Moving seasonally to different ranges allows the animals to find the most nutritious plants in the spring and summer, and to retreat to lower, warmer elevations in autumn and winter. Herds that have been blocked from migrating often produce fewer young and eventually decline in population, so the conservation of migration routes is key to maintaining abundant herds.

Bridger-Teton set a new standard for identifying and conserving migration routes when the Forest Service amended its management plan in 2008. In that amendment, forest managers designated the Path of the Pronghorn migration—which traces the annual trek of an antelope herd between the Green River Basin and Grand Teton National Park—for protective management.

Gannon Castle/USFWS

Additionally, the state has designated a corridor used by the Sublette mule deer to migrate from the Red Desert of southwest Wyoming northward to their summer range on the forest’s Hoback Rim. The Sublette herd gained fame in the wildlife conservation community in 2011 when scientists revealed the animals’ 150-mile trek; previously, it was not generally known that mule deer migrated so far. The report shows how the Path of the Pronghorn and Sublette mule deer migrations fit into a larger context of wildlife migration across the Bridger-Teton forest.

Teddy Collins

The Forest Service can use the report as it prepares to revise its management plan for Bridger-Teton. The agency recently announced that its plan revision effort will kick off in fiscal 2023. 

The report, which can be downloaded here, has an accompanying online mapping tool that allows users to explore all the datasets in greater detail.

Matt Skroch is a project director and Leslie Duncan is a senior officer with The Pew Charitable Trusts’ U.S. public lands and rivers conservation project.