Two researchers release a mule deer with a tracking collar around its neck.
Mule Deer Collaring Mule Deer Collaring © Kathy Lichtendahl

Stories in Wyoming

Room to Roam: Studying Animal Migrations

Research on migration will help protect vital pathways for mule deer, pronghorn, sage grouse and other iconic Wyoming species.

This page was updated on September 21, 2020.

Tracking Migrating Mule Deer

Wyoming is home to some of the country’s most impressive wildlife migrations—pathways that animals have followed since ancient times. For many, successful migration is a matter of life or death—they must successfully reach the places where they feed, breed and rear their young to maintain healthy numbers. 

One of Wyoming’s longest and most iconic migrations is the seasonal journeys made by mule deer from their summer grounds in the high country, to lower elevations with less snow and severe weather. But, as ubiquitous as mule deer are in Wyoming, their numbers are actually in decline. Researchers have discovered that we really don’t know enough about their seasonal journeys. What are their routes, where do they stop to feed and rest and what are the biggest risks they face along the way?

In the northern Bighorn Mountains, The Nature Conservancy and partners have joined forces to fit dozens of mule deer with satellite collars to map and study their movements in detail for the first time. This study will gather valuable information that can help stakeholders better understand mule deer seasonal habitats, habitat use and movement. 

Armed with this information, decisions can be made with public and private land managers to conserve and improve habitats and migration corridors. It could also help inform potential transmission risks for chronic wasting disease in this herd. Our goal is to improve habitat, guide forest planning, modify fences and inform hunting season schedules.

Three mule deer among vegetation look at the viewer.
Mule Deer in Wyoming Mule deer at Torrey Creek Trailhead, Wind River Range Wyoming. © Scott Copeland

Fences Block Access to Feeding Grounds

Imagine if every time you try to go to the grocery store, you encountered roadblocks that made you travel miles out of your way to get there. For some wildlife, that’s what fences are like. Many typical fences can be a real obstacle for migrating animals such as deer, elk and pronghorn.

If a top wire is too high, it’s impossible for some animals to jump over. If it’s loose, it can entangle a leg and lead to a slow, agonizing death. At the same time, if a bottom wire is too low, young animals and pronghorn, who are not good jumpers, cannot crawl under. Barbed wire fences also pose a special hazard for greater sage-grouse who, with their limited eyesight,  can fly into a fence since they don’t see it. And in the relatively treeless sagebrush prairie, fenceposts make great perches for flying predators such as hawks.

Making a fence wildlife friendly is a fairly easy and inexpensive fix. But, with thousands of miles of fencing crisscrossing the American West, it’s a good idea to first identify the real problem spots. TNC’s study in Wyoming’s Bighorn Mountains and in other areas of the country can help locate those areas and help landowners make smart decisions about where to make modifications.

Human Development Impedes Migration

Fences aren’t the only obstacle to wildlife migration. Human development can interrupt the smooth flow as can roads. TNC is using research on animal migration patterns to help prevent wildlife-vehicle collisions

Sage grouse at sunrise stands among a field of sagebrush.
Male Sage Grouse A Greater Sage-Grouse (Centrocercus urophasianus) in Wyoming. © Tatiana Gettelman