On a sunny morning this past winter, I packed my snowpants and prepped my gear: two black garbage bags 鈥� one filled with a large hunk of raw meat and the other, a glass jar filled with a skunky-smelling liquid and wrapped in white towels. Not your normal winter hiking gear, but this was not a normal winter hiking expedition. I was headed out to check a North American wolverine study station at a remote location in southwest Idaho.
Josh Collette, a natural resource specialist for the Boise National Forest teamed up with me for the trip. The survey station at the end of our hike is designed to collect wolverine DNA from a 鈥渉air snare鈥� station. Animals are attracted to the station with meat bait and scent lure. The hairs are snared on the stiff bristles of a gun brush (normally used to clean the barrel of a firearm) as animals pass by to investigate the enticing smells from the bait. The hairs collected by the brush are used to identify and determine the sex of the animals. This station is a part of a larger network of DNA and camera traps in southwestern Idaho that aim to get a better understanding of wolverine population density, genetics and habitat use in southern Idaho.
Wolverines are a member of the weasel family and the size of a small labrador retriever. They are mostly meat-eating scavengers, eating carrion from winter-killed deer, elk and mountain goats. They will also hunt small mammals, including pikas, ground squirrels, and porcupines, as well as eat bugs, berries, eggs and roots. Wolverines generally avoid people and are difficult to see, making them hard to study. They are also declining in population, due to habitat loss and disturbance, and are listed on the Endangered Species Act (ESA) as threatened. Understanding the existing population will help the U.S. Fish and Wildlife Service recover the species so that it no longer needs ESA protections one day 鈥� which is why the agency funded this study in southwest Idaho.
Collette and I drove as close to the station as we could, then parked the truck and pulled on snowpants and snowshoes. After packing up the survey gear, we shuffled over the snowbank up the side of a hill toward the study station. The hillsides were steep and awkward to climb with snowshoes, but I clambered up them with all the grace someone lugging a bag filled with carrion and skunk lure could muster. Collette chatted about how this season鈥檚 trap checks had been going as we climbed (and occasionally slid) up the trail to the high elevation site. They already had one wolverine detection this year. But that detection came at the cost of frostbite on his neck acquired while snowmobiling to check that site the week prior 鈥� despite wearing extensive neck coverings and layers. I was quietly thankful that fate landed me a site visit on a sunny and mild day!
As we arrived at the station, it was immediately apparent that a large amount of snow had fallen since the last visit. A leg bone, clean of any meat, was strapped to a tree with a wire just above some gun brushes covered in orangey brown hairs that were only a couple of feet from the top of the snow. We checked the camera card to see what had come to nibble on the leg and investigate the skunk lure. Several birds visited the meat leg 鈥� Steller鈥檚 Jays, mountain chickadees and Canada jays were visible in the camera trap photos. Some dark images with eyeshine flicked across the screen, then a few shots of a fox popped up followed by a very charming American martin investigating the bait. Based on the time lapse of meat disappearing, it looked like the martin had the lion鈥檚 share of the bait. No wolverines this time, but it was very cool to see the setup attracting some elusive critters.
We then collected the samples and reset the station. I unscrewed the gun brushes, which were covered in hair, and put them into coin envelopes to be sent off for DNA analysis while Collette worked on piercing the replacement meat chunk with baling wire. I hopped up on a tree ladder to drill screws into the tree and fasten wire to them, then attached a sponge to the wire and dipped it in the super smelly skunk lure. The meat in combination with the strong skunk scent would, with any luck, attract a wolverine to the site. As I screwed in clean gun brushes below the bait setup so that any mammal that climbed the tree to take a bite would rub its hair against them, Collette moved the camera facing the setup higher up the tree and popped a new camera card in. Voila! The site was now ready for wolverines to visit.
Between the hair snare and the camera trap, the hope is that animals visiting the site will be individually sexed and identified. This extensive effort across southern Idaho will allow us to better understand how many wolverines are using our national forests, their genetic diversity and what locations they prefer.
It doesn鈥檛 get much better than being in the mountains on a clear, sunny, winter day, even if you are carrying smelly meat and skunk lure! The results of this study will help biologists like Collette and me determine where wolverines are living in Idaho and how best to help them recover.
