Alpine enigmas: Researchers work to improve management of bighorns, mountain goats

MISSOULA – The best way to catch a bighorn sheep is with a helicopter. You also need favorable conditions, good planning and a little bit of luck.

“The capture is the hardest part, and the biggest part, manpower-wise,” said Dan Walsh, leader of the U.S. Geological Survey’s Montana Cooperative Wildlife Research Unit, and Distinguished Affiliate Faculty within the W.A. Franke College of Forestry and Conservation at the University of Montana. “This is dangerous terrain.”

Generally, the best practice is to fly up and deploy a giant net over them. Then, if the sheep can’t be examined on the spot, they have to be carried in giant slings underneath the helicopter to a place where they can be safely examined. All the while the health of the captured animals is top priority. Researchers take extreme care to monitor the sheep, making sure no harm comes to them.

Sometimes, though, sheep and goats congregate in places not even helicopters can reach. In those cases, you do things the old-fashioned way: Hike up the mountain on foot or on horseback to set up drop nets or clover traps.

Either way, these animals make you work for it.

“It’s a bit of a rodeo,” Walsh said.

Bighorn sheep and mountain goats are among the American West’s most iconic species, prized by hunters and wildlife watchers alike. For centuries sheep have been regarded as sacred by some Indigenous groups, often represented in pictographs and other writings. Their distinctive, rounded horns have also been used to advertise wildlife organizations, sports teams and trucks. In Montana, sheep and goats have become synonymous with our wild spaces, often used on postcards and marketing materials for state and national parks.

Ironically, their rugged, remote habitats also make them some of the area’s most mysterious animals. For biologists and researchers, just getting their hands on them is half the battle. As a result, sheep and goats remain relatively understudied compared to more visible local ungulates like deer and elk.

This winter, Walsh and his team hope to change that.

In year two of a five-year study funded by Montana Fish, Wildlife & Parks, UM researchers from the Wildlife Biology program, side by side with co-principal investigator Dr. Nicholas DeCesare and other Montana FWP researchers and biologists, will capture, collar and track as many sheep and goats as they can. It’s a sprawling effort, bringing together state and federal agencies, private landowners and scientists, with the goal of analyzing and streamlining population management efforts throughout the state.

The study will survey and analyze data across 13 distinct bighorn sheep herds in Montana. Last year, the team was able to collar 128 sheep. This year they are out for more and are adding mountain goats to their capture list.

“I think it’s one of the largest efforts undertaken in Montana for bighorn sheep — and for sure for mountain goats,” Walsh said. “The idea is to try to accelerate our learning around the best way to manage these animals.” 

Catch and Release: Monitoring Populations

What scientists do know is that, unlike many of their terrestrial counterparts, some bighorn sheep populations haven’t totally bounced back from their lowest points in the early 1900s, when a combination of overhunting and disease led to a steep decline in overall numbers. Today, factors including predation, disease, habitat loss and a changing climate have kept sheep numbers in flux. With goats — which are even more difficult to find and to get official permission to collar — it can be hard to get any information at all.

Government agencies like FWP have historically used an array of techniques to keep sheep and goat numbers stable and on an upward trajectory. These approaches include the removal of sick animals before disease can spread among their herds, and translocation (a strategy that involves moving healthy animals from thriving herds to those that need support). Controlling predator numbers and expanding sheep and goat ranges are also employed.

But the isolated nature of individual sheep and goat populations and lack of a means to coordinate and evaluate the impacts of different management actions, make it tough to tell what is and isn’t working. Walsh’s study aims to create a clearer picture.

By tracking an unprecedented number of the animals across multiple years and creating a standardized framework to evaluate how they respond to management actions, they can help biologists gauge the effectiveness of various management techniques on different herds, in different areas. This framework will become an important tool to inform and adapt statewide policy on sheep and goats.

First, they just have to catch them.

UM’s Groundbreaking Research

In addition to the many public and private strategic partnerships involved in the study, Walsh’s effort uses vital input from a pair of UM doctoral students in the Wildlife Biology program.

Kaitlyn Vega oversees a disease-focused study of the Highlands sheep herd in southwest Montana, monitoring a type of pneumonia-causing bacteria that can cripple herds once it takes hold.

Colton Padilla is responsible for the computer modeling that crunches and analyzes data produced by Walsh’s project. He also writes research proposals and papers based on the study.

Vega’s work, which she conducts in collaboration with FWP research biologist Dr. Kelly Proffitt and Butte area biologist Vanna Boccadori, tracks the spread of a bacteria called Mycoplasma ovipneumoniae (M. ovi, for short). M. Ovi is a respiratory pathogen that can turn some sheep into “chronic carriers” that remain infectious over multiple years. Because bighorns are social animals, the chronically infected sheep can spread the disease through the herd again and again.

“Picture if you had a cold virus for many years in a row, and each time you came in contact with somebody, you could give them a cold, even if you didn't feel sick at the time,” Vega said. “That’s what happens in sheep sometimes with this particular bacteria.”

The Highlands herd was once popular with Montana hunters, but after an initial bout with M. ovi during the 1990s, its current population can sustain only one or two tags per season. Vega’s team thinks it might be because of chronically infected sheep. In an attempt to stabilize and restore the herd’s numbers, Vega’s team will ramp up M. ovi testing throughout the five-year study. Sheep that test positive at least two years in a row will be considered chronic carriers and be removed from the herd.

“It seems sad to have to remove those sheep,” Vega said, “but if that saves a lot of other sheep from potentially getting sick and dying, then it's worth it for the betterment of the herd.”

Meanwhile, information on management techniques from all over the state contributes to Padilla’s computer modeling. Among other data, he tracks survival rates, immigration between herds and annual numbers of offspring to map population trajectories.

“I build what are called integrated population models,” Padilla said. “Those models create a framework for us to smash together all the data that we have on sheep and goats. It allows us to merge multiple data sources into a single analysis.”

In layperson’s terms, more data generally equals more precise results. So, being able to compile information from Montana’s far-flung sheep and goat herds into one framework allows researchers to more accurately predict the effectiveness of various management techniques. 

For sheep, that includes disease risk modeling. Padilla uses past data along with the numbers compiled by Vega and others in her current study to forecast the likelihood that different sheep populations will suffer a significant disease event in the future.

All of this can inform the way FWP manages different herds — and as years pass and more information is added, the computer models will only improve.

“Being able to have all that data in one place is good for the biologists of the future,” Padilla said. “Plus, they’ll have data that builds on this project in the future. This is just a start.” 

Going After Goats

When the topic of mountain goats comes up, Walsh can only laugh.

“Everything about goats is hard,” he said. “They’re hard to observe, and they live in areas that are very, very hard to access.”

The trouble is two-fold: First, the aforementioned inaccessibility of mountain goat habitat. Second, many goats live on designated wilderness areas within national forests or national park land, which makes getting permission to go in and capture them difficult.

The lack of access makes it challenging to collar enough animals to gauge overall population size and density. What little information is available says that mountain goat numbers vary wildly from herd to herd. In some areas, native herds have experienced extreme population decline, while many introduced herds seem to be thriving, and researchers aren’t sure why.  

Walsh hopes they can start to unravel some of the mysteries surrounding goats when they begin this winter’s captures — but he admits success is not guaranteed.

“We’ve identified some herds that we think we can get to,” Walsh said. “So, we’ll see what we can do.”

Ultimately, Walsh’s work underscores an integral part of the mission of UM’s Franke College as a whole: to do the cutting-edge work necessary to answer Montana’s most enduring and important questions. Those answers will help preserve the state’s natural resources for generations to come.

Now, the University of Montana Foundation and Franke College are joining forces with the “Treasure Montana: Cultivating Our Tomorrow” fundraising campaign. The UM Foundation seeks to inspire $20 million in private support for a new state-of-the-art, 60,000-square foot hub for environment and conservation research and instruction on campus. The campaign will match $25 million committed to the project by the Montana Legislature in 2021.

Treasure Montana offers donors the opportunity to make an immediate impact on a college that is working to meet Montana’s most daunting environmental challenges. 

With sheep and goats, that means identifying the best ways to stabilize and restore population numbers and helping land managers mindfully apply them throughout the state — even if it means scaling a mountain or approaching a wind-swept peak through the air.

    Field researchers blindfold a bighorn sheep for to study and tag it during a winter capture in 2023. (Photo courtesy of Colton Padilla)