From tracking mortality to interstate crossings, officials use GPS collars to study mule deer

CEDAR CITY — Now that spring has sprung and the winter snowpack continues to melt in the higher elevations, mule deer herds throughout Southern Utah are starting once again to make their way back to their summer range.

A buck mule deer undergoes brief health testing before being fitted with a GPS collar, date and location of photo not specified. | Photo courtesy of Utah Division of Wildlife Resources, St. George News / Cedar City News

This past winter, wildlife and land management officials placed electronic collars on 50 mule deer in Southern Utah in an effort to precisely track the animals as they migrate between their summer and winter ranging areas.

The project is part of a collaborative effort between Utah Division of Wildlife Resources and the U.S. Bureau of Land Management. The two agencies are partnering to fulfill big game conservation objectives set forth in the UDWR’s Wildlife Migration Initiative of 2017 and a directive from the U.S. Secretary of the Interior called “Secretarial Order 3362: Site-specific Management Activities to Conserve or Restore Big Game Habitat.”

The DWR and the BLM split the cost of the GPS collars and their deployment, which involved briefly capturing the animals using a helicopter and affixing the collars around their necks (see video in media player above).

The collaring program is part of a statewide effort that began two years ago. Josh Pollock, a DWR conservation officer, told Cedar City News that of the 50 collars fitted a few months ago, eight were placed on mature bucks, and the rest were placed on does and fawns. The deer were captured and collared in several areas throughout Southwest Utah, including in Washington, Iron, Kane and Garfield counties.

Phil Tuttle, a DWR outreach manager who works at the agency’s Cedar City office, said the data being collected is helping biologists determine not just where the deer go but also such things as their mortality rates, their eating habits and the impact of urban growth and other human activity on their behavior.

“As they move, they use the same migration corridors that were taught to them by their mothers and their mothers’ mothers, and so forth,” Tuttle said. “That first year, they make that migration with their mother as fawns, and then they make that same migration, usually on almost the exact same path, or within a few feet of it.”

Tuttle said the GPS collar technology was exciting because it not only shows them where an animal is at a specific time, but they can also manipulate the intervals of how often the signal is sent.

“That gives us a lot more detailed information,” he said. “It can tell us where they are every half hour as they’re moving across the landscape.”

A mule deer is captured using a helicopter before being fitted with a GPS collar, date and location of photo not specified. | Photo courtesy of Utah Division of Wildlife Resources, St. George News / Cedar City News

As one example of how the data can be used, Tuttle said knowing where the deer are likely to cross roads and highways can help Utah Department of Transportation officials know where to place deer crossing signs and other mitigation projects to prevent deer-vehicle collisions.

Dustin Schaible, a BLM wildlife biologist, said both agencies stand to benefit from the collaborative effort.

“From the BLM’s perspective, we had the secretarial order that was promoting migration corridors and looks at the kind of things that we authorize on the ground,just to make sure we’re not impeding the national movement of some of these species that are migrating,” Schaible said. “This project aligned greatly with the division’s needs, and it was just one of those projects that can all came together.”

Another example involves how habitat can be managed to make sure suitable vegetation is available as food sources, Pollock pointed out.

Pollock explained that federal and state habitat treatment plans over the next few years call for cutting down excess juniper and pinyon trees in certain areas, as those plants don’t provide much in the way of nutritional value for deer.

“They’re going to go knock those pinyon-juniper back and plant grasses, forbs and shrubs, that kind of stuff, to enhance the habitat so those deer have a better place to move,” Pollock said.

Tuttle said that at the time of capture, each of the collared deer was also given a brief health assessment, including the taking of blood samples.

“We actually do an ultrasound on their backs to measure the amount of fat that they have, and that’s a measure of the condition of the animal,” Tuttle said.

A recent DWR press release noted that the Utah’s mule deer survival rate for the winter was favorably high this year, at 92 percent.

Read more: Despite harsh winter, deer survival is good statewide; DWR seeks input on big game permits

Phil Tuttle of Utah Division of Wildlife Resources uses tracking software to monitor movements of mule deer, Cedar City, Utah, Feb. 21, 2019 | Photo by Jeff Richards, St. George News / Cedar City News

Tuttle said this week that although statewide aggregated numbers for GPS collared deer are not yet available, the Pine Valley unit, for example, saw an even higher survival rate of 98 percent, with 43 of 44 adult does making it through the winter alive.

Some deer have already started their migration back to their summer range, Tuttle said.

“This process often takes longer than the fall migrations, as they follow the ‘green up’ on the snowmelt line back up to the tops (or wherever they choose to summer).”

Tuttle says the collaring project is one of several ongoing collaborative efforts to improve the management of big game animals and the land they inhabit.

“Rapid growth in Utah has greatly increased demand for water, energy, housing and other resources, which can significantly impact big game movements and habitats,” Tuttle said. “Knowledge of how these species move and use their habitats is critical to success.”

Tuttle says the tracking system can tell when a collared animal has died, because the signal stops moving, at which point workers will go to the location to retrieve the device so it can be reused. As a side note, it is perfectly legal to shoot a buck wearing a tracking collar, provided it is in season and all other laws and regulations are followed. Any hunter who harvests a legally taken collared deer is asked to report it to wildlife officials for data collection purposes.


  • Website explaining scope and purpose of BLM directive.
  • Fact sheet about Utah mule deer migration, courtesy of Mule Deer Working Group via UDWR.
  • Video showing how GPS and mapping technology is helping reduce airplane-pelican collisions in Utah.

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