WIND RIVER VALLEY—Biologists Tucker Russell and Rene Schell stopped in their tracks.
Spooked out of a daybed, a mule deer doe sprung to her feet. She bounded up a gentle, grassy slope amid badlands-like rock formations overlooking the Wind River, then froze, staring right back.
But Russell, with the University of Wyoming, and Schell, with the Wyoming Game and Fish Department, had eyes on something else.
A still-spotted fawn.
Within moments, the youngster abandoned its hiding spot, bolting for mom. The doe’s days-old progeny complemented the high desert’s sagebrush steppe, which was in springtime bloom. Russell, a master’s degree student, snapped some photos of the fawn, a welcomed distraction from research that’s wrapped up in death. The Lander native is part of an effort to understand why this Wyoming mule deer herd is more infected with chronic wasting disease than any other.
After the fawn bolted, Russell got back to work, using a phone app to locate a GPS collar needing retrieval. A couple days before, it dropped off a still-living deer — one of the lucky ones.
Russell’s master’s degree work is part of a multi-agency study that’s exploring how migration and habitat use among animals in the Project Mule Deer Herd play a role in the transmission of chronic wasting disease, an always-fatal condition that’s on the rise in Wyoming.
The herd wasn’t chosen arbitrarily. It’s one of the most CWD-infected wild deer herds known to exist on the planet. Sky-high prevalence of the incurable prion sickness — three in four deer with antlers suffer from the disease in the core herd area — have long raised concerns for the well-being of the central Wyoming deer herd, which largely dwells within the borders of the Wind River Indian Reservation.
It’s still early in the study, which launched in early 2023 with 40 GPS-collared deer. Russell doesn’t even know which of the animals have or had CWD, although he will soon — even the living ones, thanks to a new testing technique that uses ear tissue.
Ahead of the data dump illuminating how CWD-infected deer are using the landscape differently, an eye-opening discovery has emerged. The collared deer are dying at horrendous rates that threaten to wipe out the herd. Typically, adult doe mule deer have about an 85% chance of surviving any given year. In the Project Herd, however, only half of the first cohort of 30 GPS-collared does lived through their first 12 months as a research deer. The bucks, more prone to CWD, fared worse. Three out of the 10 tracked males were still breathing after one year, but by the time WyoFile rendezvoused with Russell some 15 months into the study, 90% were dead. A single buck remained.
Unlike in other portions of Wyoming, winter wasn’t to blame. Humans weren’t the direct cause, either. “We didn’t have a single hunter harvest,” Russell said.
‘Not going to have deer’
The Wyoming Game and Fish Department biologist whose district includes the Project Herd used the words “poor” and “awful” to describe the survival rates.
“We’re not going to have deer, at this rate,” Dubois-based biologist Zach Gregory said. “I don’t literally think there’ll be zero deer, but people should probably get used to not having many deer there.”
Coming up with survival rates and any demographic data on the Project Herd is meaningful because relatively little is known about it. Partly, it remains shrouded by the unknown because of the lines humans have drawn marking the herd unit and other boundaries. The core of the habitat is privately held property: agricultural land enabled by the Midvale Irrigation District, which is embroiled in a historic dispute with the Eastern Shoshone and Northern Arapaho tribes over water rights. Project Herd mule deer that migrate into the herd area’s fringes in hunt area 171 tread into tribal lands outside of Game and Fish jurisdiction.
The state agency historically did not estimate the population because of those access hurdles, instead relying on hunter satisfaction and landowner surveys to gauge its status.
Satisfaction has steadily plunged: More than 80% of surveyed hunters were pleased with the experience as recently as 2018, but the last two years the metric is in the 40-50% range. Now, there’s a population estimate also.
In the winter of 2022-’23, the state agency conducted an inaugural aerial “sightability” survey of the Project Herd, Gregory said. The effort produced a first-ever population estimate of just shy of 6,000 animals. While there’s now finally a baseline, the biologist has a hunch that the count still needs significant fine-tuning. Many of the deer surveyed on tribal lands in hunt area 171, he said, were likely sojourners from the Dubois Mule Deer Herd.
Gregory is more confident in the estimate from the core of the herd unit around Pavilion, Ocean Lake and Boysen Reservoir. There, in hunt area 157, numbers registered at just shy of 1,300 mule deer.
Hunter-killed deer in this agriculturally dominated area have the highest rates of CWD. The region is among the first in Wyoming where testing is mandatory for both mule and whitetail deer.
The three most recent years of test results show that 74% of buck mule deer killed by hunters are in the process of dying anyway from CWD. Does — the reproducers that drive any herd’s trajectory — fare better, but still 41% test positive and would likely die within a couple years from a disease that turns cervid brains into swiss cheese. Even a third of the 1-year-old bucks have CWD. It means they won’t likely see the age of 3.
“When you start seeing the yearling mule deer have that high of a prevalence, that’s pretty alarming,” Gregory said. “Most herds in the state, you’re seeing animals that are older having [CWD]. Usually, younger animals like yearlings haven’t lived long enough to gather enough prions to make it a problem.”
Came on fast
Something about the landscape in northern Fremont County has allowed CWD to thrive. Prions — the misfolded protein vectors of the disease — can live outside of animal hosts, propagating through the environment.
“I think one of the things that’s very striking here is the speed at which this came on,” said Paul Cross, a U.S. Geological Survey research biologist who’s partnering on what he calls the Wind River Project. “Up until the mid-2000s they had almost no detections of CWD in this region. It was pretty low [prevalence], and then all of a sudden, over a 10- to 15-year timespan, it got to over 60%. That, to me, is pretty surprising for CWD — it’s pretty fast.”
Because there were no estimates of the Project Herd’s size while CWD ramped up through the 2010s, biologists and others are left to imprecise anecdotes to gauge its population effects. But by all accounts, the disease has walloped mule deer numbers, killing animals at a faster rate than they’re reproducing.
“Based on hunter observation, landowner observation and [Game and Fish] personnel observation,” Gregory said, “we’re not seeing the deer that we used to.”
Ken Metzler had a front-row seat to the crash. When WyoFile first discussed CWD’s impacts with the Riverton-area outfitter in late 2021, he estimated that his deer hunting operation had fallen off by 80%. Virtually every animal his paid hunters killed on leased agricultural hunting grounds — 98%, he estimated — tested positive for the disease.
Nearly three years later, Metzler reported that he’s given up on his commercial deer hunting operation altogether.
“We’re pretty well shut down,” he said. “I’m not booking any deer hunters. I can’t promise something that isn’t there.”
The 67-year-old outfitter has witnessed the Project Herd cycle in the past, and he retains some hope that it’ll bounce back.
“It’s getting worse right now, but it’ll turn around a little bit,” Metzler said. “If it comes back, it comes back — but it’s not looking too good right now, that’s for sure.”
Persistently high CWD prevalence rates don’t help the odds the herd will recover on its own. Even while deer numbers have tumbled, the lethal prion disease hasn’t let up, Game and Fish data shows. That suggests that animals are getting it directly from the environment — not each other.
Nevertheless, Gregory doesn’t want deer numbers to increase because of its potential to further exacerbate transmission.
“Hunter success is down and the number of animals harvested is down, but we’ve just got to maintain the same harvest, because we don’t want high deer density,” the biologist said. “We want to keep it low density, like it is. Maybe even lower.”
But Wyoming Game and Fish harvest reports suggest hunters have quickly lost interest in the area. As recently as 2020, Wyoming was issuing nearly 500 licenses in the Project Herd’s core hunt unit, 157. Nearly 60% of hunters actively used their tags, and they managed to kill an estimated 201 mule deer. The 2023 hunting season looked dramatically different: Only 126 licenses sold and fewer than 40% of hunters used their tags. Those who did killed an estimated 20 deer — 10% of the harvest from three hunting seasons prior.
Containing the contagion
Gregory’s aim for hunters to keep up the pressure on a collapsed population stems partly from a desire to contain the contagion as best he can, even if spread is inevitable. Through the CWD study, Russell, Gregory, Cross and other project partners have learned it consists of a mix of resident deer, short-distance migrants and animals that tread dozens of miles into the mountains and high desert — and they intermingle, also with adjacent deer herds.
“We’re starting to see more CWD headed upstream toward Dubois,” Gregory said. “We’re nervous that it’s an area they’re traveling back and forth.”
Dubois Herd mule deer, in turn, mix with Sublette Herd deer that summer in Grand Teton National Park and the Gros Ventre Range. It’s all linked by the marvel of the Greater Yellowstone Ecosystem’s migrations.
To try to limit the spread, Game and Fish increased the hunting quotas and extended the seasons in area 171, the Project Herd’s more peripheral hunt area.
“It was already pretty liberal,” Gregory said. “Again, we just don’t want a lot of deer in there.”
Data that Russell, the University of Wyoming graduate student, amasses on how CWD-positive deer are using the landscape could also help inform management decisions. Based on preliminary survival numbers, he expects that the herd’s long-distance migrants are the least likely to have CWD. Residents that never really leave agricultural land in the core hunt area, 157, likely have the highest rates, he said.
The coming CWD test results from the initial cohort of 40 research deer that have died in droves will help clarify the picture. An additional 42 GPS collars went out on another batch of mule deer in February, and scientists are expanding the research effort to include whitetail deer starting in 2025 to see how the species are intermingling.
“Whitetail deer CWD prevalence [in the Project Herd unit] is actually lower than the mule deer prevalence,” USGS’ Cross said. “That’s not typical.”
As the research matures, the window into the world of Project Herd deer should become increasingly clear. Eventually, Gregory might know exactly where animals are getting CWD.
“Through [Russell’s] work, we’re hoping to identify hotspots,” he said. “Then we could target [those areas] with some kind of license to remove deer — really reducing deer.”
Another possibility, the biologist said, would be to use fencing to keep the most contagious areas devoid of deer.
Wyoming wildlife managers could even turn to some of the methods they’ve been using to address overpopulated elk herds: Tactics like “auxiliary” hunts and paying technicians to kill elk, which stretch the boundaries of typical hunting-based big game management.
Whether the Game and Fish Commission will authorize outside-the-box changes to mule deer management to address CWD-superinfected herds remains to be seen.
Hank Edwards, a longtime Wildlife Health Laboratory supervisor who retired last year, said he and colleagues ran into resistance time and again when the agency attempted to manage the disease. It persisted right up until his last Game and Fish Commission meeting in July, when lawmakers and outfitters pushed back on plans to target more bucks as a means of addressing the lethal disease.
“When I left the department,” Edwards said, “the majority of [Game and Fish staff] just had given up on doing any CWD management because it had gotten so combative.”
There’s a contingent of management-averse Wyoming sportspeople, he said, who are “organized” and have been “able to shut down anything” biologists tried to do to address CWD.
“When you get to 65% prevalence, it ought to be bad enough that some of your detractors should at least let you try some things, but that hasn’t happened,” Edwards said. “How many people have to harvest a CWD-positive animal before the department is going to be allowed to do CWD management on any of the herds in this state?”
Recently, Josh Coursey, who heads the Muley Fanatics Foundation, caught up with a Fremont County rancher who pointed out that 75% of the alfalfa hay grown in the area where the superinfected Project Herd dwells gets shipped out of the region. Given that CWD prions can uptake into grasses, it made him wonder if the livestock feed exports were inadvertently spreading the disease.
“It was thought-provoking,” Coursey said of the rancher’s premise, “and it kind of gave me the shivers.”
Seeing the plight of the Project Herd, Coursey’s ready to see more aggressive CWD management.
“To do nothing is not the answer,” he said. “We need to be learning, and the only way you do that is by attempting things. We’re behind the eight ball.”
Collateral damage
My guess is agricultural chemicals and herbicides. The spread could certainly occur from spreading hay all over God’s green earth. In Washington, we have hoof rot, now CWD is showing, and a good many of knowledgeable people have pointed to the timber companies who spray so their precious little trees can thrive. In Washington, the cause for hoof rot was attributed to a bacteria, then ascribed to a different kind. Wyoming G&F was following behind with alternating theories but using as cause the same bacterium that Washington had just thrashed. This has happened several times in recent past. All these states paying outrageous wages to doctorate level people and each state trying to re-invent the wheel. For starters make this a Federal problem and throw the covid people at it; they at least figured it out somewhat in less than a year. Currently all the different G&F’rs should quit and get some real biologists to attack the problem. Chemicals in our world are destroying all that is good..
Excellent Article. I live in Southwest Montana and the deer here are plentiful but are coming down further into populated areas, it would be interesting to know if hot spots are created by something if environmental and not passed inside the herd what effects this will have.
Thank You
Why aren’t’t they slaughtering every deer, like the govt slaughters millions of chickens “suspected” of Bird Flu?
Are the deer getting any shots when the GPS Trackers are put on them? Is there a danger to hunters eating the venison? Something seems weird about this….
Is it possible that cwd is caused by a chemical reaction to something used in agriculture? Remember DDT almost wiped out the bald eagle.
Wipe out the predators, post nearly all the land no hunting and this is what you get. It’s happening all over the place not just Wyoming.
So what causes this CWD. It seems that more farm & animal epidemic are due to increased human encroaching on habitat.
There has been two cases found in California now. And there will be mandatory test in the zone areas where it was found. CDFW is asking hunters in all other zones to voluntarily have their deer tested.
Another clear example of why science should be the guiding & determining factor in wildlife management in WY rather than managing the wildlife like domestic animals for profit. That is what can be expected when the WY G&F commissioners are predominantly stock growers & outfitter who only see our most valuable resource as a commodity.
CO used eradication in areas of high prevalence with positive results. With such a high potential to infect other migratory herds, strategic deer herd reduction would seem to be the best short term solution. This is also consistent with WGFD’s CWD management strategy which is available on the WGFD’s website.
Looking at you ft Collins research facility that kept scrapie infected sheep and deer in the same pen. That area in Colorado is the epicenter. Prions are the ice nine of pathogens. How could they have been so careless and when can we stop funding them?
I would like to see test results of genetic and prion variations in the local herd that appears so susceptible to CWD. I suspect this herd lacks intrinsic resistance to the CWD prion and is doomed. Most herds studied have some intrinsic resistance in the population( eg, 225F allele in mule deer in Colorado’s epicenter for CWD) that increase in prevalence over time, if not suppressed by culling. Replacing the local herd with ones that have shown resistance may be the only alternative. At least they won’t have to learn migration routes. The less affected migratory herd probably has some resistance.
I would cut some slack to the Wyo G&F. No wildlife department in any state has “managed or controlled” CWD. Management usually equates to slaughter (no deer=no positive CWD tests). No one knows what to do and rarely admits it. Oklahoma is taking a novel and highly risky approach. They are going to introduce deer into the wild population that have been captive-raised and shown to be genetically resistant to CWD. It might work and it might be a disaster. Of course, the captive deer farmers will make money including the legislators who are in the business. Man’s hubris that nature can always be fixed by human intervention is remarkable.
An ecological disaster and the lack of a unified effort to solve this from all interested parties is shocking. Not the America I remember where people put differences aside came together and solved problems and respected one another. Never be solved until that happens.
I agree 100% I live in Missouri and we;re battling CWD also, but our Conservation Dept had been working on it for many years now. They have mandatory deer checking the first weekend of rifle season and typically test around 30,000 deer each year. they post the results for each county and usually give more tags and drop any antler point restrictions, also where they do fined positive deer they ask permission to go in and try to kill deer right around the area and typically kill several more positive deer, they also offer extra tags to the landowner if they want them. I beleive they are doing the best they can with a bad situation
Perhaps, if Wyoming didn’t have such a liberal kill every wolf in sight outside of National Parks, there might not be such widespread occurrence of the disease. Wolves notice much better either by scent or by slight motion that a human hunter could never detect ,the early signs of the disease and they don’t seem to be affected by CDW,nor is it spread by their scat, I read in one article last year. I don’t remember publication. But it makes sense. Predators take out the weak and the sick. Just as vultures aren’t affected by rotted meat due to makeup of stomack acid. Nature takes care of itself. It doesn’t need management or it didn’t until it was over managed. And get rid of the feed lots. That’s a great way for disease to spread. The dear don’t congregate naturally in such high numbers.
The other side of that argument for more wolves to solve things is the fact CWD wasn’t a problem prior to the wolf introduction. Is there a connection? I don’t know, but one has to consider that. What is the prevalence of the disease in high wolf populated areas as opposed to non wolf populated areas? We have to consider the fact it has become a problem SINCE the introduction of the wolves. O doubt they are connected, but the fat is the disease has increased with the wolf numbers.
To those who think we need more wolves in the project herd need to remember the Wind River Reservation has a very healthy wolf population and prey on these deer routinely in that herd. It hasn’t curbed the CWD and if humans shouldn’t eat CWD tainted meat then why should wolves be allowed to eat it. Just what we need a new prion affecting our wolf populations due to poor game management.
Very informative article Mike. If increased harvest is the preferred alternative, just go ahead and hire the gun thugs. Having killed 5 positive animals across three species, my incentive to hunt in the Project is less than zero. Based on the declining hunter participation rates you described, others feel the same way.
Great job, Mike. Keep it up. From your pal up north.
Meanwhile, the Wyoming Game Commission is actively persecuting the one species that has been shown to curb the spread of chronic wasting disease dramatically: wolves.
Remarkably, this article mentions human hunting, which leads to wanton waste of the animals since they’re not consumable, and even spending taxpayer dollars on technicians to remove animals or potentially spending millions of dollars to fence them out of the most contagious areas. Why not let natural biology do what it does best: manage game populations through predation?
The Wyoming Game Commission recently said they were the gold standard in wildlife management, yet they overlook a natural approach to a terrible problem. Talk about shortsightedness and not by any means a “gold standard.”
We’ve been using medicated salt blocks & mineral supplements for about 20 years and our whitetail and mule deer are doing great … A lot more cost effective and whole lot less political!!!
CWD is the type of disease that predators used to control. I would look to this states anti wolf policies as the cause of this out break. Two things; wolves have the ability to early detect prion disease, praying on these animals selectively and are immune to prion disease. Put two and two together and figure this out. Yes, without the wolves controlling the CWD in the deer the ranchers are going to spread Sponge Form Wasting disease to cattle wherever they send their feed too. So much for the idea that the presents of wolves do ranchers no good.
How about doing your job and telling the readers the specific reasons “project” deer are dying? The media is constantly used to push an agenda. Were the captured deer tested? Where’s the rest of the story? As far as I know, no one has fought the G&F on management seasons where this project is. This story is being used to push a statewide agenda to reduce mule deer bucks or overall herd numbers. After one year of killing doe mule deer near Casper the surprising fact is the prevalence rate in bucks and does there is the same, around 25%. Everywhere else G&F try to compare prevalence numbers there are very few tests on doe mule deer. But not surprising the public is being blamed because the wildlife professionals don’t have a clue how to stop CWD.
Jeff, did you try modeling what the prevalence rate in the Casper herd would have been had the does not been killed? My point is, experts have jobs to think about these sorts of things that the general public isn’t thinking about. I can’t speak as an expert like the fine scientists in G&F, University of Wyoming, and USGS as brought up in this article, however I can speak for the scientific process. I will always advocate for means testing hypotheses and figuring out what works and what doesn’t. If we want scientific management of wildlife, we must accept that science doesn’t yet have all the answers and we need experiments to figure that out. If we can accept that the ‘do nothing’ alternative is to reach the state of Riverton’s resident mule deer herd, then the world-class biologists thinking about this problem might as well run experiments on managing CWD and evaluate their outcomes in other locations around the state before it gets that bad. A fella smarter than me said it best: ‘If you kill of a bunch of mule deer over a few seasons to try and manage CWD, it’s kind of like getting a bad haircut. They’ll grow back in time.’ If you do nothing and it becomes too late with CWD, there’s no growing back given the current state of prion disease technology.
There is a very simple and free solution to this problem. Stop killing every wolf you see. They eat the infected deer and it’s been proven over and over. That is the best way to manage herds.
Humans hunting and using animals as we see fit, (which is a God given right in the book of Genesis 1 26-31), is natural predation. Hahahaha. nothing makes a better rug than a wolf skin. Anti-hunters and wolf lovers, who have done nothing to bring wildlife populations back from the lows at the turn of century should not be bringing their emotional baggage instead of reality to make decisions on how to manage wildlife. Game and fish is making a bunch of assumptions based on no real scientific data that it will even work.
Excellent story on CWD issues, Mike. Great field photography and maps.
Yes, this plague will continue to spread from herd migration
but also through alfalfa & hay shipments.
Maybe a UW masters student will take on that research project.
Keep up the good work!
A huge step would be to ban outfitting aka welfare program where profiteers leverage the state’s wildlife inventory @ pennies to the the dollar. Extremely poor Game and Fish leadership needs to be fixed asap, also
Dale, as a “welfare recipient” who has spent his life pursuing and propagating these animals, and has spent countless hours in meetings with people who actually care about them, searching for solutions, I applaud your stone throwing from the cheap seats. Keep doing that, I’m sure it’s the cure…
Why are outfitteres that only take from the system allowed to a seat at any table, from the legeslature to Game and Fish meetings on wildlife management? Maybe higher Outfitter lisencing fees and trophy fees from the outfitters would be appropriate and use this money to fund the CWD research. Are some of the biologist getting access to outfitter lease hunting for their recommendations? Are state legislutures getting access to outfitter leased stuff too?
This is an excellent piece about the problems of CWD including the political, economic and other aspects of trying to manage for CWD. There are no easy solutions.
Keep up the good work Mike.