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'Doing my part': Hunters, landowners and wildlife managers team up to fight chronic wasting disease in southwest Montana

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CWD Hunting Trip

A trail in the snow around Garrett Harshbarger’s land in Waterloo marks the spot where Spencer Obresley dragged a deer carcass toward his truck on Jan. 31.

WATERLOO — Garrett Harshbarger hasn’t seen any classic symptoms of chronic wasting disease in the white-tailed deer around his property near the Jefferson River, but last summer, he watched a young, healthy-looking buck die suddenly.

He wondered if the prion disease had killed it, but he never took it in for testing.

It wasn’t until December, when members of the Montana Fish and Wildlife Commission approved a special CWD management hunt in Harshbarger’s area, that he began to worry about the deadly prion disease reaching the deer on his land.

Death in infected animals is slow and sure, and wildlife managers have struggled to limit spread.

Data collected by Montana Fish, Wildlife and Parks during last year’s general hunting season indicated prevalence of CWD in whitetails in and around the Ruby Valley ranged from 8.3% in Hunting District 320 to as high as 50% in a specific portion of district 322. Harshbarger’s land in Waterloo — a tiny town between Twin Bridges and Whitehall — lies in 320.

The Fish and Wildlife Commission approved the two-month CWD management hunt in nine hunting districts around Sheridan and Twin Bridges. The goal was to reduce population densities among whitetails and slow further spread.

They wanted to act quickly and aggressively, as deer in the region “are seasonally connected to migratory populations of elk, moose and mule deer that occupy adjacent upland habitats.” The hunt ran from Dec. 15 to Feb. 15.

Nick Gevock, conservation director for the Montana Wildlife Federation, said in December that the rates were “staggeringly high,” especially since the disease was first introduced to the valley just a year ago. “That suggests either it’s been there a lot longer than we realized, or the spread is extremely rapid, or both,” he said.

Large herds of whitetails have always congregated on private land in Harshbarger’s area, he said. Deer populations in Waterloo have been dense for as long as he can remember.

On Jan. 24, a friend of Harshbarger’s drove to the property with high hopes of bagging some deer and helping the landowner collect some data on the herds.

Spencer Obresley of Belgrade was glad he had another opportunity to punch his unused general deer license from 2020. He bought an additional tag to improve his chances.

CWD Hunting Trip

Waterloo property owner Garrett Harshbarger, left, and hunter Spencer Obresley, right, retrieve the carcass of a white-tailed doe Obresley shot on Jan. 31. Harshbarger said the herds of deer on his property have been dense for as long as he can remember.

Obresley’s plan was to shoot at least one doe, then get the meat tested for CWD. He’d send the results back to Harshbarger, who hoped to track CWD rates on his land.

However, Obresley’s ultimate goal was to help FWP cull the herd and collect more data, he said. He worries about Montana ending up like other states with really high CWD infection rates.

If rates reach levels seen in other states, “realistically, in 10 years, there could be almost no whitetail and mule deer left in the state,” he said.

On his first trip to Harshbarger’s land, dogs chased the deer off. He decided to try his luck the following Sunday.

Obresley arrived at dawn. The deer ran away and hid in a grove of cottonwoods. Obresley waited quietly for them to withdraw from the cover. When they did, he shot one doe. Then another.

CWD Hunting Trip

Spencer Obresley prepares to gut a doe he shot on Waterloo landowner Garrett Harshbarger’s property on Jan. 31.

“Usually when I shoot a deer I have this little bit of guilt and sadness because I just killed something,” he said. “Not this time… It felt like I was doing my part to help more than it was me going out to shoot a deer because I like to eat them.”

As he gutted the does, Obresley was careful not to cut through the brain and spinal cord, as deadly prions tend to accumulate in those body parts. He tossed the carcasses into the back of his truck and took them home for processing.

Back at home, Obresley removed and bagged the lymph nodes, which he said look like “small, peeled cloves of garlic.” He later took them to FWP’s Bozeman regional office for sampling. He tossed the rest of the parts into his trash, which gets taken to a certified landfill.

Obresley hadn’t gotten the test results back by Saturday. But preliminary data on white-tailed deer harvested during the hunt suggests 52 out of 300 samples, or around 17%, turned up CWD positive or were suspect.

Emily Almberg, a disease ecologist with FWP, wrote that 311 white-tailed deer samples total were collected during the hunt, 11 of which still await results. A few more samples will likely trickle in during the next couple of weeks.

Since testing during the special management hunt wasn’t mandatory, there could have been hunters that killed animals but didn’t get them tested, Almberg noted. The samples therefore represent a minimum number of total harvests.

Almberg said hunters in CWD surveillance areas should have their meat tested, even when an animal doesn’t look sick.

“For a long time we were telling people what to look for, and we’re still interested in any animal that displays obvious symptoms, but those shouldn’t be used as a diagnostic tool,” she said. “The vast majority of our positive animals are apparently healthy.”

Species barriers have kept CWD from infecting non-cervids, but the Centers for Disease Control and Prevention advises people not to eat CWD-positive meat.

Montana’s CWD Management Plan notes that if the disease could spread to people, “it would most likely occur through eating of infected deer, elk or moose.”

Almberg said CWD is a strange disease because it’s not a virus, bacteria or fungus. It’s caused by a misfolded protein or “prion.”

After an animal picks up one prion, other proteins in its body begin to misfold. Then, the prions accumulate. The animal sheds them as it feeds, drinks, breeds and beds down with other members of the herd. The prions can stay infectious in the environment for more than two years.

After about a year passes, symptoms start to kick in. The animal loses weight. Its cognitive functioning wanes. It doesn’t respond normally to things like noise from humans or predators. It drools and hangs its head low. If it isn’t picked off by nature or killed by a car or hunter, it lingers on until it succumbs to tissue death or nerve and brain damage.

Some deer, moose and elk die sooner than others, but the 100% fatal disease usually takes around two years to run its course. No cervids are resistant to CWD prions, and “right now it’s not obvious we’ll see true resistance,” Almberg said.

Patterns in other states have shown that population stagnation or decline can start to occur in deer and elk populations when CWD reaches 15% to 25% prevalence, according to Almberg. In Montana, officials hope to keep transmission rates below 5%, she said.

Lone White-Tail Deer

A white-tail deer on Monday treks through snow at the nature sanctuary at Story Mill Community Park.

CWD first appeared in captive deer at a research facility in Colorado in the 1960s. It reached wild deer in the 1980s. Then it progressively spread to 24 states in the Midwest, Southwest and East Coast. It reached Montana’s wild herds in 2017.

Despite the state’s best efforts to limit spread, CWD has continually popped up in new places within Montana. Last June, the state adopted a CWD Management Plan, which lays out strategies for expanding disease surveillance and ramping up testing of game.

Almberg said CWD is spreading through Montana from the north, east and south.

Even if FWP were able to keep the disease under control in the state, constantly fighting spread from neighboring states and provinces would be extremely difficult, she said.

“We made a conscious decision when revisiting our CWD management plan that we weren’t going to aim for eradication. It just didn’t seem practical,” she said.

Almberg said officials are figuring out where to prioritize surveillance efforts next year. Monitoring will probably occur in southwest, northwest, southeast and eastern Montana, though the areas haven’t yet been determined.

Almberg said factors that contribute to spread include high deer densities and improper carcass disposal. At a Montana Fish and Wildlife Commission meeting in early February, officials passed a new rule restricting the transportation of deer, elk and moose carcasses statewide.

All hunters are now required to either leave the spinal column and head of deer, elk or moose hunting in Montana at the kill site, or ensure that the parts are disposed of at a sanctioned landfill. The ungulate parts identified in the rule are where deadly prions tend to accumulate.

Agricultural land and river bottoms— the kinds of environments that characterize the valleys west of the Tobacco Root Mountains — tend to attract lots of deer. Transmission rises when deer densities are higher, according to Almberg.

To reduce deer densities in CWD-positive areas, Montana officials use hunters. Because of the strategy, it’s critical to get private landowners on board, Almberg said. If landowners don’t grant access, it’s hard for FWP to manage the disease.

CWD Hunting Trip

Waterloo landowner Garrett Harshbarger sits on the bed of hunter Spencer Obresley's truck as he waits for Obresley to finish gutting two deer. Harshbarger hopes data on the does will help him track chronic wasting disease rates on his property.

Dean Waltee, an FWP biologist who oversaw the special hunt in southwest Montana, said landowners and ranch staff were extremely cooperative throughout the process. Many went above and beyond, granting hunter access and even helping them to collect and submit game samples, he said.

Waltee has monitored deer populations in the Ruby and Jefferson river valleys through aerial and on-the-ground surveys since 2014. The counts don’t tell him exactly how many deer there are in the entire valley system, but they reveal overall population trends.

In the Ruby Valley, Waltee has seen a slow and steady increase in whitetail populations over time. At the lowest population point of the year, deer densities in certain parts of the valley can range from 20 to 80 deer per square mile, he said.

“Within those areas, at certain times of the year, particularly in the winter, those deer will concentrate even further to take advantage of relatively limited winter forage sources,” Waltee said. At their highest, densities can range from dozens to several hundred deer in areas that are very small.

According to Waltee, the high and dense populations of whitetails are primarily sustained by deer foraging from haystacks, which becomes a problem with diseases like CWD.

Animals concentrated in small areas are “urinating, defecating and putting saliva on vegetation through foraging… Then other deer are there putting their mouths at the same spot,” which raises the probability of infection up substantially, Waltee said.

The Ruby Valley between Sheridan and Twin Bridges was a focal area for the hunt because sampling showed around 40% of deer there were infected with CWD, Waltee said.

CWD Hunting Trip

The sun rises up from the Tobacco Roots on Jan. 31 by Waterloo, a town between Whitehall and Twin Bridges.

But Waltee is also concerned about areas on the fringes of the hotspots where more whitetails are concentrated at high numbers. Biologists have now detected CWD at lower levels — less than 5% prevalence — around some of these areas, he said.

“Without reducing those deer populations now, I believe we’re going to see CWD prevalence there like we’ve detected currently in the lower Ruby watershed,” he said. “And it’s going to reach levels that are bound to have population-level impacts on those deer.”

Also of concern to Waltee are the elk, moose and mule deer whose ranges overlap with the infected whitetails. If the high densities of whitetails are maintained, “we are going to expedite transmission into those other cervid species,” he said.

“It’s important for hunters to realize that maintaining the concentrations of whitetailed deer that we’ve had in southwest Montana over the last 20 or 30 years is not going to be effective for CWD management,” Waltee said. The levels of mortality that could ensue “may not be sustainable for these populations.”

CWD Hunting Trip

Hunter Spencer Obresley, left, and Waterloo landowner Garrett Harshbarger, right, retrieve a second doe that Obresley shot on Jan. 31. Obresley killed two white-tailed deer for a CWD management hunt that officials approved in December.

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Helena Dore can be reached at hdore@dailychronicle.com or at 582-2628.

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