Wolverine, lynx populations fluctuate in Southwest Crown of the Continent
(Missoula Current) Long-term monitoring is revealing where Canada lynx, wolverine and other smaller carnivores travel through the Swan, Clearwater and Blackfoot watersheds and how disturbance, human or otherwise, may play a role.
Last week, biologists Luke Lamar and Mike Mayernik of Swan Valley Connections presented initial results from monitoring species during winter throughout the Southwest Crown of the Continent since 2012. They focused on threatened species or species of interest like the Canada lynx, wolverine and fisher but also looked at pine marten, mountain lions, bobcats and wolves.
The good news is they’ve regularly found traces of elusive wolverine and lynx, although both have changed through time. Sadly, no fishers have been found.
“When we started, we really didn’t know how many wolverine, lynx and fisher were here and how they were distributed across the Southwest Crown. So that was one of our main objectives: to see the distribution and abundance of those animals across the landscape,” Lamar said. “Then we wanted to help facilitate adaptive management of those species over time.”
The Southwest Crown is an area of about 1.5 million acres extending from north of Condon in the Swan River valley to south of Lincoln along the Blackfoot River. Much of the land is still fairly wild, with most of it belonging to the Bureau of Land Management and U.S. Forest Service, including parts of the Bob Marshall Wilderness, intermingled with private and Nature Conservancy property.
To learn about distribution, biologists divided this area into 73 grid cells of 25 square miles each, and nine more cells were added south of the Crown to include public land in the Garnet Mountains. They aren’t able to get onto some private land or go very far into the backcountry.
Then, every winter between 2013 to 2016, Lamar, Mayernik and about 30 technicians rigged up 65 bait stations throughout the mountains, trying to locate at least one in every grid cell. At each station, they lashed pieces of road-killed deer and elk on trees to attract the carnivores, brushes to snag hair for DNA analysis and set up game cameras to see who came to the station. Also, at 150 locations, they hiked transects of more than 6 miles, looking for signs of each species.
Between 2013 and 2016, the biologists tallied a total of 32 unique wolverines and 39 lynxes throughout the area.
The number of lynxes almost quadrupled from 7 in 2013 to 27 in 2016, although the cats frequented about the same 20 grid cells every year. The increase may be due partly to biologists refining their techniques over time, such as learning that lynx don’t come to bait stations as much as wolverines do. Alternatively, tracking surveys don’t tend to reveal as many wolverines as lynx.
The number of wolverines detected also increased, but to a smaller degree, going from 10 in 2013 to 18 in 2016. However, wolverines appeared to expand their area from 16 to 43 grid cells over the four years.
“We don’t fully know why,” Lamar said. “Coincidentally, in 2012, Montana put a moratorium on (wolverine) trapping, so it could reflect some of that.”
One popular spot for both lynx and wolverine was the swath of mountains and lowland between Seeley Lake and Condon. Other spots included the southern edge of the Scapegoat Wilderness northwest of Lincoln and the mountains south of Lincoln.
Then, in 2017, several wildfires, including the massive Rice Ridge Fire east of Seeley Lake, brought change to the Southwest Crown.
“It was timely that we did those surveys from 2012 to 2016,” Lamar said. “The fires affected a large area of the Southwest Crown and some areas that were some hot spots of lynx and wolverine. That gives us the opportunity to see how changes, natural disturbance, change the distribution of these animals.”
Biologists didn’t repeat their surveys until five years later. In the meantime, however, a smaller study determined that there’s no longer a viable population of lynx in the Garnet Mountains where a reproducing population existed 20 years ago, Mayernik said.
Those five years also included the COVID pandemic, which brought a surge of tourists and home buyers into the once sleepy valley and surrounding recreational sites, causing their own form of disturbance.
Last winter, the biologists returned to monitoring their sites in the Southwest Crown, rigging almost 240 bait stations and tromping almost 4,500 miles looking for tracks. The early results appear to indicate that the lynx and wolverine populations have swapped places.
Biologists identified 35 lynxes, a number similar to the early studies, spread out across more of the Seeley-Swan valley than before, particularly along the Mission Mountains. The lynx distribution looked more like that of the wolverine in 2016. Alternatively, they found only 13 wolverines in an area about half the size of the 2016 results.
“Take it with a grain of salt, because this is comparing one year to four years,” Lamar said. “In 2021, remember, there was not a lot of snow, especially on the Swan Range. This area was very difficult to access in the early part of the season, and the snow started to melt early in March. So, we didn’t have a super long window to get in, and I think that shows to some degree in our results. That’s why it’s important to monitor this for more than one year.”
Last month, a 10-year Canadian study using similar methods showed declines in already low wolverine numbers and distribution between 2011 and 2020, even though much of the area they monitored was protected in the Banff, Kootenay and Yoho national parks north of Idaho and Montana. They found wolverine density was three times higher in protected areas “underscoring the importance of protected areas for wolverine conservation.”
“However, wolverine detection probability was negatively correlated with human development and with human activity, emphasizing potential detrimental effects of recreation activities, which are often concentrated within protected areas,” the study concluded.
Biologists with the Swan Valley Connections, U.S. Forest Service, Bureau of Land Management, Montana Fish, Wildlife & Parks and the Blackfoot Challenge will continue the monitoring this year. But without the early monitoring to provide a baseline, there’d be no way to know if change has occurred, Mayernik said.
The data also helps agencies understand how to manage wildlife and habitat. For instance, whether FWP should limit trapping, whether the U.S. Fish and Wildlife Service should consider protecting a species or whether a logging project would harm wildlife. In fact, the Swan Valley Connections work appears to have spurred the Forest Service to conduct similar monitoring in nine national forests in Montana and Idaho.
“The Forest Service biologists use our data a lot in their environmental analyses. A lot of folks know the Forest Service gets sued a lot, particularly over timber projects, particularly in lynx habitat. And they’re often sued for a lack of data,” Lamar said. “So the biologists are super happy to have our data to be able to say that lynx exist in that project area, don’t exist in that area or maybe we need to be more careful in this area because it’s a hot spot.”
Contact reporter Laura Lundquist at firstname.lastname@example.org.