Animals’ changing migration routes may impact how you drive and hunt

In about one week in January, the Utah Division of Wildlife Resources relocated 11 loose moose — five of which were found along Interstate 80, prompting lengthy road closures to prevent crashes.

A new report from the Pew Charitable Trusts suggests these dangerous conflicts may become more common in Utah as herd migration routes in the West are cut off because of property development, roadway construction and climate change.

“It’s really important that those connections remain in place so they can get between winter and summer areas,” said Daniel Olson, who previously worked as the DWR’s wildlife migration initiative coordinator. “When when we build interstates or we build new cities, and they block those migration corridors, we can lose half of the habitat for that species if they can’t get between those areas.”

The report found that hoofed mammals — like mule deer, elk and pronghorns — are especially dependent on migration for herd health. And disruptions to migration patterns — like highways or new construction in the path of a historic migration route — result in declining animal populations.

Study author Matt Skroch directs Pew’s efforts to conserve wildlife corridors in the West. He said Utah is a leader in research efforts on migrating wildlife — especially since the state is home to the nation’s first wildlife overpass, built in 1975.

“In Utah today, thousands of data points regarding wildlife movement are collected on a daily basis,” Skroch said. “So Utah really has more data than most states regarding this issue... That data is so valuable and so important for being able to guide decisions, whether that’s management decisions or policy decisions that ultimately dictate and affect how our populations of wildlife are managed.”

Utah’s main migration corridors — the paths that animals use to travel between summer and winter habitats — are along the state’s mountain ranges, stretching from the southwestern corner of the state to the northeastern corner.

Impact on herds

Animals that encounter roads or development may move quickly through the area, which can result in unhealthy herds — because herds rely on many “stopover” areas to rest and refuel. Mule deer in Wyoming spend 95% of their time at stopover areas, according to the report.

And if herds decide to cross a road blocking their migration route, it can have deadly consequences. About 200 people and 1-2 million large mammals die from vehicle collisions in the U.S. every year, the report states.

Utah’s large hoofed migratory mammals — called ungulates — also make important contributions to ecosystems and economies. As prey animals, they provide food for other carnivores and scavengers, while also facilitating plant dispersal through foraging.

Economically, they also bring in revenue through hunting and wildlife watching. Herds across the western U.S. bring about $1 billion annually to the national economy, according to the report. A 2013 report from the Congressional Sportsmen’s Foundation stated that Utah hunting in particular generated about $550 million in spending and over 12,000 jobs.

But data from migration activity has shown how challenges to migration corridors can threaten these species — and a recent study from Brigham Young University showed that Utah’s elk were leaving public lands at the first sign of hunting season to take refuge on private lands.

“As a general observation, private lands and migrating wildlife most often mix during the winter months,” Skroch said. “Because private lands are often in valley bottoms, which is where these migrating wildlife invariably ended up during the winter months.”

Human development like fencing, roadways and energy production operations also damage migration routes that deer, elk and pronghorns have relied on for years — contributing to resource scarcity and deadly wildlife-vehicle wrecks.

“Especially in the winter months, when animals are at lower elevations seeking out lesser snowpack, perhaps leftover forage from the growing season, we need to acknowledge that all land tenures are important for management of these of these wildlife species,” Skroch said.

Preservation steps

Skroch’s report lists out recommendations to conserve these dedicated migration pathways in order to avoid declining species populations. It’s a team effort to maintain these routes, he said, and Utah agencies have recognized that.

That’s because Utah already practices many of these recommendations — like increasing mapping efforts, which Utah implemented in 2017 through the state’s Wildlife Migration Initiative. The state also is a leader in implementing wildlife-crossing structures and is home to over 50 of these crossings already.

Right now, the DWR is focusing on the I-80 and I-84 interchange near Echo Reservoir. Many ungulates move through this area as a part of their winter range, said DWR habitat manager Daniel Olson, so they are installing wildlife fencing to funnel these herds to safe underpasses.

Eagle Mountain has been a particular focus for the DWR as well because the community has grown rapidly and sits in a deer migration corridor. The agency has been working with city planners to align green spaces with these migration corridors so deer can still retain their winter and summer ranges in the area.

Deer are Utah’s main migratory ungulate species, Olson said. They usually move 15-20 miles between their summer and winter residences, but some move up to 80 miles. Other species like pronghorns likely had longer migrations in the past, but due to human obstructions, they don’t migrate as far now.

“I think we all kind of use similar tactics,” Olson said. “A lot of these animals are moving long distances — which span several ownerships... It takes a bigger collaborative effort to maintain migration corridors because they cover such large areas.”

Research like Skroch’s helps demonstrate the importance of natural habitats, and how crucial it is to maintain these migration pathways, Olson said.

“Migrating wildlife in Utah are an incredibly important and valued resource for the state,” Skroch said. “The challenge and the opportunity is translating the knowledge that we now have — from the GPS collars, the scientific inquiries — and translating that knowledge to conservation action, and actual management that will ultimately conserve these populations.”