One doe mule deer took off from the Pilot Butte area in the middle of the Wind River Indian Reservation and trekked roughly 90 miles northwestbound. She ascended the foothills, then high country, crossed the Continental Divide and spent the summer deep in the Teton Wilderness north of Jackson Hole.   Another GPS-collared mule deer was drawn southeast, likely migrating along a path learned from mom. Some 60 miles later, the animal landed at its preferred summer habitat: Near the Oregon Buttes, off South Pass.  Migrations like this are celebrated and even occasionally protected because of the clear biological benefits, but wildlife managers would prefer these deer stay put. They’re part of the Project Mule Deer Herd, which has the highest rates of chronic wasting disease documented in any wild ungulate herd on the planet.  Other members of the research cohort — 111 deer were captured over several years — shot out in different directions. They migrated dozens of miles, ending up in summer habitat not far from Dubois, Lander, near Beaver Rim, the Sweetwater River drainage and the southern tip of the Wind River Range. In winter, however, the animals hang in an area where the always-lethal prion disease has been catastrophic, cratering survival rates, populations and hunting opportunities.  “They’re eventually going to pick [CWD] up and take it out with them,” Wyoming Game and Fish Department wildlife biologist Zach Gregory said. “That’s the concern.” A significant portion of mule deer that winter in the Project Herd area spend their summers elsewhere. It’s a concern for wildlife managers, because the herd has the highest prevalence rates of chronic wasting disease anywhere in North America. (Native American Fish and Wildlife Society) Now, Wyoming wildlife managers are taking steps to prevent the CWD-infected mule deer from spreading CWD prions via their migrations. Saving other deer herds might come at the cost of the Project Herd losing its migration routes, but the aim is to stop the devastation from repeating elsewhere.  Starting in 2025, the Wyoming Game and Fish Department opened up hunting within the herd unit to over-the-counter “general” season tag holders — a plan they’re repeating. And this coming fall, the agency is proposing to adjust hunting seasons in two adjoining mule deer herds in hopes of killing more antlered deer — it’s bucks that carry the highest rates of the disease.  “The change to a general season this last fall, our attempt is to maintain as high a harvest as we can on bucks,” said Daryl Lutz, who coordinates wildlife management for Game and Fish’s Lander Region. “It will maybe help protect some of the surrounding herds from having chronic wasting disease, or an increased amount of it.”  Lutz was addressing a roomful of hunters who convened on March 26 for the state agency’s annual “season setting” meeting in Riverton. They were in the domain of the Project Herd, a population that may never recover from CWD’s destruction. “This might — and I emphasize, only might — help with deer here,” Lutz said. “But we may be way too late.”  “It’s a scourge,” he added, “there’s no question.” Continued devastation At the Riverton meeting, Gregory walked the 18 hunters who attended through the latest data on the Project Herd. The plight of 53 collared mule deer that were alive at the onset of 2025 told the story: Only 29% of the bucks and 44% of the does remained on their feet at the end of the year. The rest tipped over.  Wyoming Game and Fish Department Wildlife Biologist Zach Gregory, who works out of the agency’s Lander Region, discusses mule deer migration at a July 2024 meeting in Dubois. (Mike Koshmrl/WyoFile) “You won’t grow deer that way,” Gregory told the crowd.   It’s an insurmountable rate of death compared to the average annual survival rate of 85% for female mule deer in the Intermountain West.  Unsurprisingly, chronic wasting disease was the leading cause of death. The incurable prion disease killed 36% of all the research animals over the last four years. But 26% of the mortalities were “unknown” and the true toll CWD was taking was “likely higher,” Gregory said. “We’ll get to sites where the deer is dead, and there’s nothing left,” Gregory said. “And so, we don’t know.”  When enough tissue was available to test dead deer for CWD, they had it 72% of the time.  (Wyoming Game and Fish Department) That statistic comes from a recently published study led by former University of Wyoming graduate student Tucker Russell. It’s part of a broader research project that Game and Fish and the U.S. Geological Survey have been collaborating on.  Russell, who’s now a tribal liaison for the University of California-Berkeley’s Beyond Yellowstone Living Lab, also sussed out how CWD-infected deer fared relative to their disease-free counterparts. Using the “RT-QuIC” technology that can detect prions in live animals, he found that infected deer survived any given year just 27% of the time. Deer without CWD survived the year 69% of the time, according to Russell’s study.  One positive shred of evidence uncovered by Russell was that the long-distance travelers were least likely to have CWD. It’s the “residents” — those that spend their whole lives in and around agricultural areas — that have the most sky-high rates of disease.  At the Riverton meeting, Gregory showed the hunters who gathered what it looks like to encounter a dead, CWD-infected deer.  “This is pretty common for what we find,” Gregory said. “Sickly looking deer that laid down and died.”  A CWD-infected whitetail deer found dead during research on the Project Mule Deer Herd. (Matthew Bowers/Wyoming Game and Fish Department) Rates of CWD in the Project Herd have stayed “alarmingly high,” Gregory said, even as populations plummeted. Over the last five years, 62% of hunter-harvested adult bucks have tested positive. So have 33% of does and 23% of yearling males. The persistently high disease rates are a hallmark sign of one of the degenerative neurological disorders’ most harmful traits: The prions that spread CWD don’t need animals to be effective vectors. They can live and remain infectious in the landscape, indefinitely.  “It’s essentially environmental transmission now,” Gregory said. “We don’t have the deer numbers for them to be spreading it to each other.”  That underlies concerns about the migrations. Game and Fish officials understand their adjusted hunting seasons are “hammering” deer in an already struggling population, Gregory told hunters in Riverton.  It’s CWD, however, that really did the hammering.  Russell’s recent paper outlined the decline of hunting in the decade after CWD was discovered in the Project Herd. License numbers plunged from nearly 1,500 to barely more than 100. Hunter success rates did the same, declining from over 70% to nearly 30%. During the 2023 hunting season, only an estimated 20 deer were killed in the Project Herd. One hunting outfitter reached by WyoFile at the time simply gave up.  Game plan Game and Fish took an abrupt turn by opening up the herd to “general” licenses in the 2025 season — a strategy the agency proposes to continue in 2026. Essentially, hunting there is now unlimited. Reducing the number of buck deer, which have higher rates of CWD, is the best strategy wildlife officials have to combat a particularly hard-to-manage disease.  “The main reason we’re really trying to harvest a lot of deer is to prevent [CWD] movement outside of this herd unit, to Dubois, to Sweetwater, to Beaver Rim,” Gregory said.  Nearby hunting seasons are also being tweaked with the same end goal.  Prevalence rates of CWD are slowly building in the migratory Dubois Mule Deer Herd, which borders the Project Herd to the west. Last fall, 14% of hunters who tested buck mule deer received a positive test result. This fall, Game and Fish has proposed increasing the length of the hunting season and the number of limited “type 1” licenses that let hunters kill antlered mule deer.  “The goal is to harvest more bucks,” Gregory said. “Just in an attempt to slow the spread and increase in CWD prevalence.” Other Game and Fish wildlife biologists in charge of nearby mule deer herds are on the same page. Rates of CWD in the South Wind River Herd ticked up from 0% to nearly 12% between 2021 and 2025. In hopes of blunting the surge, the state agency is planning to do away with antler point restrictions that safeguarded some bucks.  “It’s going to be a big change,” biologist Stan Harter told the crowd in Riverton. “It’s a hard thing to think about: Going from saving bucks to shooting a lot of bucks.”  Stan Harter staffs a Wyoming Game and Fish Department check station in Lander during the 2021 big game hunting season. When hunters stop, agency staff customarily extract a lymph node to test for chronic wasting disease. (Wyoming Game and Fish Department) Hunters who attended the Riverton meeting didn’t push back on the heavier hunting in store for several of the Wind River Basin’s mule deer herds.  Lutz even solicited their feedback: “No concerns or comments or thoughts about the Project Herd and chronic wasting disease?” he asked.  Only two people piped up.  “There’s hardly any deer here anymore,” one man remarked.  A nearby hunter piggybacked on the point: “There’s no deer left to mess with,” he said.   The newly discovered migrations might be another casualty of Wyoming’s efforts to protect mule deer herds from a particularly insidious disease that’s on the upswing.   “Some of these migration routes may be lost, unfortunately,” Gregory said. “We may likely do that, just by killing deer.” The post Hunting tweaked to target mule deer departing the world’s most CWD-infected herd appeared first on WyoFile . ...read more read less