What Technology Reveals About Wildlife Migration

GPS tracking of mule deer, other big game can help improve public lands policy

What Technology Reveals About Wildlife Migration
Joe Riis
Elk on a snowy hillside in Wyoming follow the same migration route as previous generations. But across the West, routes of numerous species are threatened by development.
Joe Riis

Technology alone cannot save the natural world from an alarming increase in human-caused threats, but it is already aiding in that effort—by raising scientists’ understanding of how some species migrate, for instance. In the American West, advances in tracking and analysis are helping researchers document big-game migrations and how habitat fragmentation affects species, including deer, elk, and pronghorn. This in turn is informing policy to protect—and in some cases re-establish—migration corridors that are vital to the animals’ survival.

Where and why wildlife travel

Many of the West’s big-game wildlife migrate between summer and winter grounds. In the spring, these animals follow a “green wave” of new plant growth up to higher summer pastures. In the fall, they return to lower valleys to seek refuge from deeper, higher elevation snow. Over time, human population growth, highways, subdivisions, and energy development have forced wildlife to alter their migration routes, putting a strain on how some herds move and survive.

Mule Deer
A mule deer crosses a road in Dubois, Wyoming. Wildlife depend on unfragmented habitat, including migration corridors, for survival.
Greg Nickerson

The intersection of technology and wildlife migrations 

By fitting animals with GPS-enabled collars, scientists are getting real-time information about where, when, and how wildlife move. The collars have revealed, for example, that mule deer in Wyoming travel more than 300 miles round trip annually—from the low-elevation winter range of the Red Desert to the mountain slopes of the Hoback Basin and back. Last April, experts discovered that at least one mule deer, Doe 255, migrated nearly 100 miles farther—into Idaho and back—prompting additional questions about the extent of her remarkable journey. 

To date, the Red Desert-to-Hoback migration is the longest known land-based journey in the contiguous United States. Tracking these deer has also exposed some of the man-made obstacles the animals face along the way, including more than 100 fences and several highways. 

Mule Deer
A mule deer in Wyoming bounds through the hills wearing a GPS-enabled collar that researchers attached.
Ben Kraushaar

New wave of policy changes 

Science is now beginning to inform policy. In February 2018, then-Interior Secretary Ryan Zinke took a positive step toward protecting migration corridors by signing Secretarial Order 3362, which directed bureaus within the agency to collaborate with states to identify and conserve routes and winter range on public lands of elk, pronghorn, and mule deer. The order, “Improving Habitat Quality in Western Big-Game Winter Range and Migration Corridors,” ensures that migration science is considered in federal land use plans. And last month, then-acting Interior Secretary David Bernhardt suggested he would expand this directive to include other species and habitats.

Wildlife migration conservation has enjoyed nonpartisan support across the West for more than a decade. Wyoming is leading the charge, with advanced policies on and approaches to corridor identification; Oregon and New Mexico are among the states considering similar action.

Sheep
Bighorn sheep, like moose and other species, learn their migration corridors from their mothers.
Bureau of Land Management

Experts, state agencies to share information

The Pew Charitable Trusts and its partners are working with state wildlife officials, federal land managers, and wildlife biologists to incorporate the latest migration science into public lands management, including discussing policy opportunities that  identify and conserve these important routes. In 2017 and 2018, Pew worked with the Western Association of Fish and Wildlife Agencies, Wyoming Migration Initiative, and other groups to host a series of migration workshops for state and federal agency staff. These sessions drew more than 250 participants, most from Western state agencies, and included training on the latest tools for analyzing migration data and discussions on state policy options.

By providing the resources and expertise that states and federal agencies need to advance wildlife migration management, Pew hopes to help ensure that the iconic big game species of the American West have room to roam and a sustainable future.

Oregon
To migrate, big game need contiguous open spaces, like this expanse in the Oregon Buttes Wilderness Study Area in Wyoming. Sportsmen, small-business owners, ranchers, and other stakeholders support conserving wildlife corridors that facilitate big-game migrations.
Wyoming Outdoor Council

Matt Skroch is a manager with The Pew Charitable Trusts’ U.S. public lands and rivers conservation team.