A study is starting up to map mule deer migration corridors across the eastern portion of the Greater Yellowstone Ecosystem (GYE). 

Since 1990, mule deer populations in Wyoming have declined due to factors including weather, habitat loss, competition, predation and disease, according to the Wyoming Game and Fish Department.

Through the 1980s the department estimated an average of around 410,000 mule deer in Wyoming, said Renny MacKay, Game and Fish communications director. The most current estimate following the 2014 hunting season was approximately 365,000. The 2014 estimate is 37 percent below the highest estimate of 578,000 in 1991, MacKay said.

“We have been losing and disrupting mule deer habitat in Wyoming and across the West, and that loss is part of the reason our herds are declining,” said Matthew Kauffman, Wyoming Migration Initiative director and zoology professor at the University of Wyoming. “This study will allow us to identify some of the key habitats that mule deer require, namely their migration corridors. This will create the opportunity for conservation groups, sportsmen groups and agencies to target those key corridors for conservation or enhancement.”

Ninety mule deer will be collared for tracking, according to Game and Fish. It will be one of the largest collaring efforts ever conducted in Wyoming, spanning an area from the Wind River valley to the Big Horn Basin.

The study is a collaboration between the Wyoming Migration Initiative, Game and Fish and The Nature Conservancy. Researchers and managers increasingly recognize the importance of intact migrations for healthy, abundant mule deer herds.

The Nature Conservancy is a project partner because wildlife migration corridors are its priority, said Holly Copeland, an ecologist in Lander for The Nature Conservancy.

The mapping project will document in detail the migration corridors of five separate herds near Cody, Meeteetse, Dubois and Lander that have never been the focus of the latest tracking technology. All 90 animals captured will be fitted with “real-time” GPS collars that send data back to researchers every three days. That represents a vast improvement over previous GPS studies that required researchers to recover dropped collars to download the data after one to three years. This left researchers only able to speculate where the deer had gone, and when, during that time period. 

In 2017, a second collaring effort will augment sample sizes on the same herds. Individual mule deer will carry the collars for up to two years, gathering movement data from spring and fall migrations.

The 2016 study is starting at square one; determining where mule deer migrate to in the spring, summer and fall, said Arthur Middleton, a researcher and study collaborator with the Wyoming Migration Initiative. “The main question is where do they go.”

It is known that muleys migrate from the east to west side of the GYE. Mule deer are faithful to their migration routes and where they bear their young in the spring, Middleton said.

GPS collars will allow them to map the migration corridors, Middleton said. Then, they can hopefully find and mitigate the obstacles to the migration routes and target habitat needs.

For example, Game and Fish wants to learn how to improve habitat where possible and protect new habitat. The Nature Conservancy hopes to identify the key environments and prioritize those as wildlife easements, Middleton said.

If the deer’s migration can be mapped, The Nature Conservancy can check the tools available in its toolbox, such as conservation easements on private and trusts land, fence modification — raising the bottom strand on fences to make passage easier for young deer and lowering the top strand to make hopping over fences safer for larger deer, Copeland said. If there are areas identified where highway deaths are high, perhaps reduced speed signs can be installed or money raised to build deer underpasses. “Nobody likes to see dead deer on the highway,” Copeland said.

The goal is to distinguish places that hamper migration or endanger mule deer. “Apply conservation money in a smart way,” Copeland said.

The real-time data will allow researchers to share what they learn with the public as collared deer migrate through one of the wildest areas of the continental United States, according to Game and Fish.

From late March through mid-summer, the collaborators will post maps of these migrations weekly on Facebook and Twitter using the hashtag #wyodeer.

There is a brief online video with Sarah Dewey, Grand Teton National Park biologist, and Tim Woolley, Game and Fish Cody wildlife management coordinator, discussing mule deer migration corridors research in the GYE at tinyurl.com/WyoDeerVideo.

The migration study is funded in part by the Knobloch Family Foundation, The Nature Conservancy, the Bole and Klingenstein Foundation, Wyoming Bureau of Land Management, Wyoming Governor’s Big Game License Coalition, Muley Fanatic Foundation and the EA Ranch of Dubois.