Wyoming Wildlife - September 2023

Just Getting Started

A contracted helicopter pilot lowers a captured mule deer in Sybille Canyon north of Laramie. Wyoming Game and Fish Department staff took samples from and collared this deer to keep track of its movements and gain more understanding of its behavior.

Game and Fish's five-year Mule Deer Monitoring Project is already providing valuable information

Chris Martin
9/1/2023 12:00:05 AM

A five-year, groundbreaking project by the Wyoming Game and Fish Department to study mule deer in the Cowboy State is underway. Less than a year into the data collection and scientific analysis, it's too early to come to any definitive conclusions from the department's Mule Deer Monitoring Project as to why the state's mule deer population is declining. 

Wildlife Health Lab Technician Maggie Johnson takes a blood sample from a mule deer captured at Sybille Canyon north of Laramie. (WGFD Photo)

Yet, some of the early information gathered, along with a new wrinkle thrown in by Mother Nature, has Game and Fish personnel excited about what they will learn.

This project isn’t the first by Game and Fish to study mule deer. Work has gone on for decades across the state to collect data about these animals ranging from population estimates, harvest and disease, to migrations, tooth aging and vehicle-wildlife collision numbers on Wyoming highways.

This project, which started in late 2022, takes a deeper data dive. It looks at six areas considered critical for mule deer management: abundance, composition, data management, survival, herd health and harvest management. One of the primary insights the project hopes to provide is how many individual mule deer are in each of the state's herds. Biologists call this abundance and know that is the key to management.

Embere Hall, Game and Fish science, research and analytical support unit suppervisor and lead on this project, said historically Game and Fish personnel measured abundance in one herd per year due to cost. In March, Game and Fish personnel wrapped up seven abundance surveys associated with this project and will do six to eight surveys per year throughout the length of the project. 

From late 2022 through early 2023, 1,112 collars were placed on mule deer from five focal herds around the state. In each herd 80 does, 30 bucks and 100 juveniles — animals at least 6 months old — were collared.

There are 37 mule deer herd units in Wyoming. Focal herds in this project include: Wyoming Range, Laramie Mountains, North Bighorn, Sweetwater and Upper Shoshone. These focal herds are located
in different parts of the state and feature many unique characteristics, which may allow Game and Fish to understand why some herds perform better than others.

"It is an uprecedented effort for the state," Hall said. "To have this sample size and this geographic breadth is incredible. Oftentimes because of the expense, we have to do all these measurements on a small subset of a herd and then assume all the other deer behave the same way and extrapolate out those estimates. With this project we don't have to, with is such a gift."

Of those 1,112 deer, 643 were still alive at the time this article went to press. Plans are being made to collar more deer in all the focal herds starting in November so researchers can continue to collect robust data.

Screenshot-2023-09-13-at-1-59-14-PM.pngThe winter of 2022-23 was harsh on wintering mule deer in Wyoming. (Photo by Elizabeth Boehm)

The winter of 2022-23 will go down as one of the more significant and devastating to mule deer in Wyoming history, especially in central and western Wyoming. Sustained snow, wind and cold temperatures took its toll. For example in the Wyoming Range herd, all 100 juveniles collared for this project died during the winter.

"Hopefully it will be a while before we see a winter like this again," said Gary Fralick, Game and Fish biologist in the Jackson Region who has done extensive work and research on mule deer in the Wyoming Range throughout his 30-plus years with the department. "It's going to take a long time for this deer herd to bounce back."

Despite the harsh winter and mule deer deaths in some parts of Wyoming, other focal herds came out of the winter quite well.

Sam Stephens, Game and Fish biologist based in Greybull who works with the west side of the North Bighorn herd, said despite lots of snow and numerous below-zero cold snaps, mule deer in his area made it through the winter well. 

“We had 89 percent of collared does survive, and juveniles fared relatively well at around 81 percent,” he said.

Zach Turnbull, Game and Fish biologist who works with the North Bighorn herd in the Buffalo and Sheridan areas, said the winter was one of the most severe in Johnson and Sheridan counties since the 1980s. However, mortality for juveniles was about 35 percent and around 12 to 15 percent for bucks and does.

“Not great, but not horrible,” Turnbull said. 

The Sweetwater herd unit is in central Wyoming surrounding Jeffrey City. Mortality of juveniles over the winter was more than 60 percent. However, doe and buck mortality rates were in the 20 and 30 percent range, respectively.

The harsh winter not only made it tough for wildlife to survive, but difficult for Game and Fish personnel to recover collars. Stan Harter, Game and Fish wildlife biologist in Lander, said U.S. Highway 287/Wyoming Highway 789 between Rawlins and Lander was closed nearly 80 percent of the time in February.

“We often couldn’t get out to retrieve the collars in a timely manner to figure out what killed the deer,” Harter said. “With a lot of the collars we found, whether the animal died first from starvation, or scavengers like coyotes found them right away or predators killed them, by the time we got to where the collars were there was nothing left of the carcass.”
Harter added some collars were dragged around by coyotes or other scavengers — several hundred yards in some cases.

If anything, the 2022-23 winter wasn’t the same for all of Wyoming and its mule deer.

Screenshot-2023-09-13-at-1-59-35-PM.pngWyoming Game and Fish Department personnel release a mule deer after fitting it with a collar. This deer is part of the Laramie Mountains herd, which is a focal herd in Game and Fish's Mule Deer Monitoring Project. (WGFD Photo)

“Being able to see some of that statewide variation was super interesting,” Hall said. “I think it’s easy to wring our hands and say ‘winter was terrible and we’re losing all the deer.’ Actually, that’s not true. We lost a lot on the western side of the state. That population really took a hit. The eastern part of the state wasn’t that bad.”


Keaton Weber, Game and Fish biologist in Wheatland, said the Mule Deer Monitoring Project is the first time Game and Fish conducted a collaring study on the Laramie Mountains herd. Weber also said despite tough winter conditions, 70 percent of juveniles, 79 percent of does and 86 percent of bucks collared for this project survived the winter.

“Survival data is some of the best information we can learn, and to have that after a harsh winter is really beneficial to us to estimate abundance and also understand how survival varies in harsh winters and mild winters,” Weber said.

Since no extensive studies have been done on the Laramie Mountains herd, any information is valuable. Weber added this herd isn’t as migratory as others around the state, but there have been some surprising movements of deer so far.

Another positive result for Weber has been with the public. The Laramie Mountains mule deer herd is predominantly on private land. Weber said landowners have shown great cooperation in granting Game and Fish access to capture deer and retrieve collars. 

GPS collars were fitted on mule deer to gather data for the Mule Deer Monitoring Project. (WGFD Photo)

“We’re fortunate to have a lot of landowners that support the department, support this project and want to learn more about the Laramie Mountains mule deer herd,” Weber said. “We’re forever grateful to them for access to their properties to learn more about this herd and why it’s been struggling. We hope to continue to have that support throughout this project.”

Screenshot-2023-09-13-at-2-00-40-PM.pngA collared doe mule deer walks just off the South Fork Shoshone Trail. (Photo by Grant Gerharter/WGFD)

Tony Mong, Game and Fish wildlife biologist in Cody, said a lot has been learned about the Upper Shoshone herd in the first year of the project.

Screenshot-2023-09-13-at-2-00-57-PM.pngA mountain lion walks off the South Fork Shoshone Trail. Mule deer in Wyoming must share trails with predators when they're on the move. (Photo by Grant Gerharter/WGFD)

“It has shown us we weren’t catching all the areas mule deer use or all the different routes or pathways they’re taking to get there,” Mong said. “It is some really cool stuff.”

Mong said mule deer in the Upper Shoshone herd move a lot, and as of mid-July there were deer from this herd in the Jackson and Lander regions. Mule deer in this herd are part of a diverse area of land that ranges from remote wilderness to highly developed private land. Some of these deer spend a lot of their time in Yellowstone and Grand Teton national parks. 

Screenshot-2023-09-13-at-2-01-16-PM.pngMule deer trek through snow in the Cody Region. (Photo by travis Crane/WGFD)

“This herd highlights the importance of collaboration and cooperation when it comes to management across every entity that has anything to do with land in Wyoming,” Mong added.

Malnutrition and starvation were the main causes of many mule deer deaths around Wyoming last winter. But Turnbull said most of the juvenile deaths in his area were due to chronic wasting disease. CWD is a fatal nervous system disease that affects deer, elk and moose and is caused by an infectious protein, or prion.

Researchers are still figuring out how and where CWD fits into the work of the Mule Deer Monitoring Project.

The University of Wyoming and the Wyoming State Veterinary Lab are key partners in the Mule Deer Monitoring Project.

UW is processing all the data from collars, in collaboration with the department’s science, research and analytical support unit. Jerod Merkle, who has a doctorate in biology and is the Knobloch Professor of migration ecology and conservation at UW’s Department of Zoology and Physiology, oversees that effort.

“The collars are functioning well and we’re collecting the data that’s coming in,” Merkle said. “We’ve had great protocols in getting the collars, getting the data off the collars and into our databases and then bringing that back to managers.”

Merkle said Lucas Olson, Game and Fish and UW wildlife data analyst, leads the data processing effort.

Focal herd managers receive real-time data and a report each Monday highlighting current survival, the number of mortalities in the past week and a map of recent movements. In addition, managers and other Game and Fish decision-makers can log in to a dashboard that shows real-time survival estimates and movements. Quick access to the data was especially important during conversations with the public this winter, as well as to the department's season setting process.

The Mule Deer Monitoring Project is the biggest and most extensive Game and Fish has attempted for deer, and Merkle said it is one of the largest projects he knows of anywhere going on at one time.

The deep snows experienced during the winter of 2022-23 forced mule deer into bigger groups than normal in areas with lower amounts of available forage. These concentrations of mule deer also made it easier for predators to pick them off, with deep snow reducing escape opportunities. This photo shows one such mule deer concentration observed during a sightability survey flight conducted southeast of Lander during the second week of February, where deep snow lingered until early May. (Photo by Stan Hater/WGFD).

Just how big?

“We’re talking millions of data points per month that we’re collating,” Merkle said. “That’s entering the big-data realm. You’ve got to have more than Excel to be doing this.”

To put that into perspective, Merkle said this project is 20 to 30 times larger than a normal deer collaring project.

If a mortality signal goes off on a collar, Game and Fish field personnel go out and collect samples, whether it be an entire carcass or whatever they can gather. The samples are sent to the lab, which prepares them for submission to a lab in Georgia to be turned into slides. A pathologist in Georgia reads those slides and gives an interpretation.

“We take what we’re seeing in the field and what the pathologist sees on the slide and put that together,” said State Veterinarian Sam Allen.

Allen added personnel who collect field samples also fill out a mortality form that includes what the scene looked like, photos and other evidence such as tracks, marks, hair, etc.

“The field folks are doing a pretty substantial investigation at the scene,” Allen said.

The lab also monitors diseases found in mule deer samples. 

Collaring more deer to keep the sample size of each herd at or as close to 80 bucks, 30 does and 100 juveniles is a priority. Data collection, analysis and lab work will continue. And, Game and Fish’s education team is putting together information from the project to engage students throughout the state.

Screenshot-2023-09-13-at-2-01-54-PM.pngPersonnel from the Game and Fish Wildlife Forensic and Fish Health Laboratory in Laramie test samples taken from deer by field staff as part of the Mule Deer Monitoring Project. (Photo by Emalee Roth/WGFD)

Hunter harvest surveys also will provide important information. Game and Fish conducts surveys of hunters each year to determine how many animals were harvested from each hunt area, how satisfied hunters were with their experience and how many days it took to harvest an animal. The surveys are a critical tool in setting seasons and allocating licenses. Hall said habitat surveys in each of the herd areas also is a part of this project, which started this summer.

Much of Wyoming saw abundant moisture not only from winter snow, but from spring and summer
rains. That moisture was good for plants and habitat for many animals, not just mule deer. How will that affect survival rates moving into 2024? Then there is the big question — what will the next winter be like?

“I’ll be excited to see if we get a more normal or traditional winter following such a wet year and our survival rebounds from 60 percent loss to 80 percent or better survival among fawns,” Harter said.

Since the project is just short of one year in a five- year time frame, there are still a lot of unknowns. It’s too early to come to many conclusions, but optimism is high.

“This is just the tip of the iceberg of what we’re going to learn,” Mong said. “This is a catalyst for learning so much more about our mule deer. I feel in five years we’ll be able to make much better management decisions and have the data to back that up.”

— Robert Gagliardi is the associate editor of Wyoming Wildlife. 


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