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Spread of chronic wasting disease may push Missoula toward deer control

A buck settles into a Missoula back yard for a midday nap. Wildlife officials believe the spread of chronic wasting disease in parts of Montana could force city officials to begin managing the urban deer population. (Martin Kidston/Missoula Current)

For years, the county and city of Missoula have punted on what to do about urban deer, but the threat of disease may finally require action.

That’s what Montana Fish, Wildlife and Parks Region 2 supervisor Randy Arnold recently suggested to Missoula County commissioners as FWP tries to stay ahead of a rapidly spreading disease that kills deer, elk and moose.

The Missoula City Council has discussed the urban deer situation off-and-on for at least the past decade, but always let it drop because of the cost. Helena is the one Montana town dealing with the problem, reducing its deer density by half over the past decade but at a cost of about $25,000 to $30,000 a year.

“We have a long history with the city and county not quite getting ready to pick that very difficult and value-laden conversation up,” Arnold said. “I’ve had a number of conversations with Mayor (John) Engen. To date, they’ve been good about saying ‘We’re interested in solving this issue, but we don’t know that it’s ripe to pick up this conversation.’”

Now, the time is ripe.

FWP biologists knew it was only a matter of time before chronic wasting disease started to show up in Montana. The disease can’t be stopped, because it’s not carried by bacteria or viruses that can be killed.

Similar to mad-cow disease, a twisted protein called a prion slowly kills an animal by forcing proteins in the body, particularly those in the nervous system, to fold abnormally so they don’t function properly. Animals pick up the prions by coming into physical contact with infected animals, dead or alive.

For the past decade, infected herds in Alberta and Saskatchewan, Canada, and Wyoming have steadily surrounded the state. By the time the first deer tested positive in southeastern Montana in 2017, FWP had already developed a plan to at least keep the percentage of infected animals to a minimum.

Since then, more deer have tested positive in Montana each year. The geographic progression of the disease was predictable, inching inward from the northeast and southeast borders.

That is until November, when CWD turned up in northwestern deer around Libby and Troy. Tests identified that almost 50 deer were infected.

FWP biologists theorized the sudden geographical jump was the result of hunters unknowingly bringing diseased carcasses back from the eastern part of the state and dumping the remains after they finished butchering. That’s where local deer picked up the disease, and it may have spread quickly because Libby also has a lot of urban deer.

Since then, two moose killed in the area also tested positive, one as recently as a week ago.

CWD has not been known to infect people, but to be on the safe side, public health officials recommend that people not consume the meat of an infected animal.

To try to limit the spread of CWD, Libby town leaders voted this week to develop a wildlife management plan that would allow the city to trap and kill urban deer, but the planning process takes too long.

Biologists estimate that as long as the prevalence in a region remains below 5%, the disease can be managed. But the more confined or concentrated animals are, such as in a town, the greater the chance of physical contact and increased prevalence.

Because the prevalence in Libby is already estimated at 13%, FWP has moved in to trap deer in Libby to regain some control.

Knowing that CWD is suddenly closer to the Five Valleys, Arnold said Missoula should get serious about writing a wildlife management plan to allow the town to monitor and maybe start controlling the deer population soon, rather than waiting until the disease arrives.

“It helps to get some baselines, and get the ball rolling,” Arnold said. “Whether you get that ball rolling with an outcome in mind or not, you’re setting expectation that something’s going to come of it.”

County and city leaders know some people like seeing deer in their yards and cringe at the thought of killing them. Emotions can run high during discussions of animal control, so some balk at addressing the issue.

“For anybody who says there’s too many deer, I can come up with just as many people who say there isn’t,” Arnold said.

But the specter of disease could tip the scales toward more control.

Arnold said the University of Montana could help by having a wildlife biology class or graduate student conduct a study of whitetail and mule deer density and distribution throughout the city.

“The university has been willing all along to help out, but we’re just in the preliminary stages of outlining that,” Arnold said. “The way to track deer in urban areas is much different from tracking with airplanes or on winter range the way we do. They tend to be nighttime and driving surveys you can replicate.”

Meanwhile, a sociological study could be designed to assess human tolerance of deer in various parts of town. From there, the studies could be expanded to other communities in the county, such as Lolo or Seeley Lake, but it would take more money.

When maps of the study results are superimposed, civic leaders could identify areas of high deer density and low tolerance where trapping could be carried out with less opposition. But if CWD works its way to the Missoula area, tolerance levels would probably have to take a backseat to disease control much as they have in Libby, Arnold said.

Contact reporter Laura Lundquist at lundquist@missoulacurrent.com