Every year thousands of elk gather in tight quarters over artificial feed at the National Elk Refuge in Jackson Hole. The good news is that Chronic Wasting Disease has not yet been detected in animals on the refuge itself but CWD has turned up in elk and deer right along its edge. Disease experts say it's only a matter of time before CWD takes hold and then it's anybody's guess what the consequences will be. Photo courtesy National Elk Refuge.
By Todd Wilkinson
On December 16, 2020, wildlife officials in Grand Teton National Park received word of something they had been dreading, and for years respected disease experts said was inevitable: confirmation that an elk taken by a hunter in the park had tested positive for Chronic Wasting Disease.
State and federal wildlife managers had known it wasn’t a matter of if, but when, wapiti congregating in Jackson Hole would come down with CWD. The test result 26 months ago further corroborated fears that the always fatal disease afflicting members of the cervid (or deer family) had reached the geographic middle of the Greater Yellowstone Ecosystem.
That discovery came two years after a mule deer buck, that had been struck and killed by a vehicle in Grand Teton Park, was the first cervid to test positive for CWD in Jackson Hole. Last fall, another mule deer buck tested for positive for CWD after it was killed in a hunting zone that overlaps with the National Elk Refuge but so far no animals killed by hunters or as part of a surveillance system inside the refuge itself have tested positive.
But as Dr. Thomas Roffe, a Montana-based veterinarian who retired a few years ago from his job as chief of animal health for the US Fish and Wildlife Service says, that, too, is unavoidable.
CWD, a cousin of Mad Cow Disease whose variant Creutzfeldt-Jakob disease killed 178 people who ate contaminated beef in the United Kingdom, is incurable in cervids that contract it.
It's important to note there has, to date, been no confirmed cases of CWD spilling over and infecting humans, livestock and wildlife (including bison) outside of members of the deer family which includes elk, mule and white-tailed deer, moose and, up north, caribou. Many authorities on zoonotic disease believe that CWD infection rates in members of the deer family are likely to rise and if prions mutate into a form that becomes conducive to infecting other mammals, spillover could happen.
The reddish portions of this map of Wyoming show how CWD has spread and areas of the state where the disease is known to be endemic. So far, CWD has not been confirmed in Yellowstone and CWD-positive animals have been found on the outsider perimeter of the National Elk Refuge in Jackson Hole. Map courtesy Wyoming Game and Fish
With CWD spreading in deer and elk populations across Wyoming in the last 20 years, and combined with the existence of 23 controversial feedgrounds where tens of thousands of elk gather in winter, disease experts forecasted CWD’s arrival and that feedgrounds will be an accelerant to its spread.
South of Jackson Hole, a moose tested positive for CWD in 2008, and subsequently deer and elk from Cody to Pinedale have been infected, too. In Montana, the state went from having no confirmed cases of CWD seven years ago to many today, including infected deer in both the Gallatin and Paradise valleys. CWD was detected for the first time in Idaho in deer and elk in 2021.
Last week a bit of positive short-term news was shared by Eric Cole, senior wildlife biologist stationed at the Elk Refuge in Jackson Hole managed by the US Fish and Wildlife Service. The Elk Refuge, because of the sheer number of elk that congregate there, is viewed in some ways as Greater Yellowstone’s best barometer for gauging CWD’s future here.
“Despite the detection of a CWD positive elk in Grand Teton National Park in December 2020, CWD has not been detected in any other elk within the Jackson Elk Herd since that time,” Cole wrote in his recent biological update, noting that CWD has not yet been confirmed on the Elk Refuge itself. “Due to early elk migration in Fall 2022, elk harvest on [the National Elk Refuge] was relatively high compared to recent years. There were 453 CWD samples collected during the Refuge elk hunt and 709 samples collected in the Jackson Elk Herd overall. This sample size is sufficient to detect CWD at 1 % prevalence with 99% confidence, and it suggests that CWD prevalence in the Jackson Elk herd remains below 1%.”
In other words, tissue samples indicate CWD has not yet markedly spread in the famous Jackson Elk Herd, following patterns established elsewhere that the disease can be slow to take hold. However, over time at other locales, CWD in both elk and mule deer exacts a deepening presence to the point it can result in herd declines.
The Elk Refuge is a place where upwards of 10,000 elk converge every winter and, in most years, they are fed supplemental rations of alfalfa pellets when natural foraging gets tough. It is highly probable that CWD is already amongst elk on the refuge but at a low level of infection, for now.
Seven years ago, CWD had not been confirmed in Montana but ramped us testing, that involves hunters submitting tissue samples of animals they have killed, show how its prevalence continues to spread in elk and deer. Map courtesy Montana Fish Wildlife and Parks
This map assembled by the USGS shows the current reach of CWD in both wild and captive cervid herds. The origin of the disease dates to the 1960s when researchers in Colorado were studying sickened mule deer at a captive facility near Fort Collins. Some of those animals escaped.
Created in 1912, the Elk Refuge is among a handful of contiguous federal public lands that encompass most of Jackson Hole and include Grand Teton Park and the Bridger-Teton National Forest. One of the reasons why elk gather there is that their instinct to migrate out of the higher-elevation valley has been lost over time and that significant development on private land has blocked an easy exodus for elk that would otherwise head to winter range at lower elevations.
This year, Cole notes that about 7,500 elk and 390 bison have been receiving artificial feed on the Elk Refuge. Even though this has been a tremendously challenging year for ungulates in Greater Yellowstone because of heavy snows and a layer of ice that has prevented animals from reaching natural vegetation, Cole said 2023 is the fourth year that his team has implemented a reduction plan to lessen the amount of time animals are given supplemental feed.
Cole doesn’t pull punches and his candor has been praised. “Current low CWD prevalence in the Jackson Elk Herd suggests that we have some time to implement meaningful mitigation measures to reduce the negative effects of the disease. However, the best available evidence suggests that CWD is now endemic to Jackson Hole (present in both mule deer and elk), and based on prevalence trends where the disease has been present for decades, CWD prevalence is almost certain to increase in the Jackson Elk Herd over time,” he writes. “Models predict that the Jackson Elk Herd will decline when CWD prevalence reaches 7%, and the 7% prevalence threshold assumes no harvest of adult female elk.”
Yes, you read that right. The Jackson Elk Herd is likely to decline even without hunters taking adult female elk. Although Wyoming Game and Fish has in recent years held a number of public meetings and taken a lot of criticism for its hesitation to shut down 22 state-run feedgrounds—some of which are located on federal Forest Service lands—it is still not budging.
The Jackson Elk Herd is likely to decline even without hunters taking adult female elk. Although Wyoming Game and Fish has in recent years held a number of public meetings and taken a lot of criticism for its hesitation to shut down 22 state-run feedgrounds—some of which are located on federal Forest Service lands—it is still not budging.
Former Elk Refuge senior biologist Dr. Bruce Smith, who today lives in Bozeman, wrote an acclaimed book, Where Elk Roam, about how feeding poses a heightened risk of elk catching disease. Wyoming continues to operate the largest complex of artificial wildlife feeding facilities in the Lower 48. He has said repeatedly that waiting until infection rates rise before more aggressive actions are taken to phase out feedgrounds is folly.
Prions, the infectious inorganic proteins that cause CWD to attack the brain and central nervous system, can be shed into the environment when animals defecate, urinate and die. Smith says there is a real concern that prions could bioaccumulate in the soils of the Elk Refuge, Grand Teton Park, the Bridger-Teton Forest and become a permanent circular source for reinfection of animals.
“Supplemental feeding clearly increases elk aggregation and density, which suggests feeding will exacerbate CWD transmission and prevalence over time. However, ending supplemental feeding on the Refuge will also result in lower numbers of elk on the Refuge and the Jackson Elk Herd overall,” Cole writes. “The total and interactive effects of feeding and CWD on elk population levels remain uncertain, but effects will likely depend on time scale (immediate reduction in the number of elk in the Jackson elk herd if feeding were to end today, versus long-term and potentially irreversible negative effects on the Jackson Elk Herd from CWD made worse by feeding.”
Defenders of the feedgrounds say that having artificially high numbers of elk benefits the hunting and outfitting industry in northwest Wyoming and lures elk away from private ranches where they are unwanted, both because of potential risk of transmitting brucellosis and wildlife competing for forage with cattle.
The Elk Refuge is currently at the end of a management plan for elk and bison that was finalized in 2007 and expected to last 15 years. In addition to feeding elevating the risk of transmission of CWD, brucellosis and other disease transmission, the refuge’s rangeland health and native plants have taken a beating from overgrazing. Both elk and bison numbers remain above the refuge’s population of objective of 5000 elk and 500 bison.
This is what a doomed Wyoming elk, sickened with Chronic Wasting Disease looks like. Symptoms include drooling, loss of physical coordination and mental disorientation, similar to human dementia patients in late stages of disease. The elk was part of a research project that confirmed there is no cure for CWD and that animals can catch the disease simply by coming in contact with a prion-contaminated environment. Photo courtesy Wyoming Game and Fish
Conservationist and independent biologists have claimed that artificial feeding is causing the Elk Refuge to violate a number of laws governing its management. As part of a management plan update, Cole wrote that in coming months “we will seek public input on management of the Jackson elk and bison herds and will analyze the relative effects of supplemental feeding and CWD on the Jackson Elk Herd over time. As part of the [National Environmental Policy Act] process, a full range of environmental, economic and cultural factors will be analyzed.”
Of course, if CWD spreads and results in significant declines of the Jackson Elk Herd, that will have negative consequences for the economy and culture of Jackson Hole. If that happens, the same questions being asked now will become more legally pressing under a blame-game scenario.
Bruce Smith said the answer as to why feeding has been significantly reduced remains has always been that politics and the power of both the outfitting and ranching industries trumps science but that an ounce of prevention is worth a pound of cure.
Besides ending feeding, there’s another aspect of prevention. Maintaining healthy populations of bears, wolves, mountain lions and coyotes that prey upon CWD-infected elk, deer and moose help remove diseased animals from the landscape. Predators are able to target and remove elk and deer that are ill but that otherwise appear healthy to humans.
Ironically right now, Wyoming, Montana and Idaho continue to promote management practices designed to dramatically reduce predators. At a public event sponsored by Mountain Journal in Bozeman this winter, that featured retired Yellowstone wolf biologist Doug Smith and outgoing Montana Fish and Wildlife Commission member Pat Byorth, Smith made a bold prediction. He said that he and others believe Yellowstone’s healthy predator population—of grizzly and black bears, wolves, mountain lions and coyotes—will prevent CWD from ever reaching high infection rates in the park.
A surprising little factoid out of Cody, Wyoming concerning CWD. We have a resident population of between 200 and 300 mule deer that either live inside the city limits all the time (including being born in town), or browse from the ever-shrinking open lands and pastures surrounding town. Wyoming Game and Fish reps reported to the mayor and city council last week that 72 percent of the Cody urban deer population tested for CWD tested positive. Just a few years ago they freaked out over having one or two isolated cases of CWD in local deer. Now they say 3/4ths of them do. Wow. I definitely want to see the data, the pathology, and anything else about how they determined this... going from 0-2 percent CWD to 72 percent in < 3 years seems unlikely. But I'm not the zoologist.
Dewey Vanderhoff
Cody, Wyoming
MoJo replies to Dewey Vanderhoff: Thanks for your comments Dewey. Anyone who wants to learn more about the startling rise in CWD cases among deer inside the city limits of Cody, Wyoming, read this story from The Cody Enterprise.
About Todd Wilkinson
Todd Wilkinson, founder of Mountain Journal, is author of the book Ripple Effects: How to Save Yellowstone and American's Most Iconic Wildlife Ecosystem. Wilkinson has been writing about Greater Yellowstone for 35 years and is a correspondent to publications ranging from National Geographic to The Guardian. He is author of several books on topics as diverse as scientific whistleblowers and Ted Turner, and a book about the harrowing story of Jackson Hole grizzly mother 399, the most famous bear in the world which features photographs by Thomas Mangelsen. For more information on Wilkinson, click here. (Photo by David J Swift).
