Capturing the Cascades wolverine

You would think it wouldn’t work.
First of all, the wolverine is an elusive creature. It inhabits the untrammeled heights of mountain ranges and is rarely seen or documented. So far this season, with ten traps open every day, we’ve captured just one wolverine. We’ve seen few tracks. But still, this winter we’re trying something new—getting photographs of the chests of wolverines. It is an idea only recently pioneered by Audrey Magoun, a wolverine researcher in southeast Alaska. And it is a brilliant idea.
Wolverines, it seems, have variable markings of light fur on their throats and chests. So variable, in fact, that each wolverine, if looked at closely, has a unique chest pattern. And therefore, with the right picture, we could tell them apart. A brilliant idea, truly, but in practice… It would seem that getting any picture of a wolverine would be a lucky convergence of circumstance, but to get a specific picture—a wolverine in a specific pose, well, it seems like wishful thinking. But then again, most great accomplishments start as silly dreams. The credit for the accomplishment of this silly dream lies to the north, with Magoun and her team of field people, who took an idea—getting pictures of wolverine chests—and made it happen. We’ve just followed their lead. But it is still exciting.
We come back to the office with a memory card, and John plugs it into a card reader and his computer. The first picture comes up on the screen—of us. It’s a motion-detecting camera setup, and we made sure it was working before we left. But there’s more. Not long after we left, a marten found the site.
This card comes from the first camera set in the North Cascades for this specific purpose. We’ve found that frozen trees are too hard for nails, pre-drilling is a necessity, and that one drill battery isn’t quite enough. There have been other minor troubles. But the real trouble is that when you’re out there in the North Cascades, you’re out there. There is no stopping by the hardware store for the one more part you need. It’s a drive to a snow park, then a ride on a snowmobile, and then a snowshoe to a site. Forgetting a tool or not bringing enough screws is a disaster, or at least an opportunity for creativity. Sometimes you just make it work.
The setup itself is straightforward. It takes two trees. One holds the camera. The other gets a “run pole” attached to it that leads out to the space between the two trees and facing the camera. Bait hangs in the middle, between the end of the run pole and the camera, but high enough that the wolverine—in theory—cannot quite reach it. The wolverine walks out to the end of the run pole, looks up, and perhaps even rears up, trying to get the bait, and the camera snaps away, taking pictures of a unique chest pattern. This eventuality encompasses a world of minor and major details. Trees the right distance apart. A convenient and sturdy branch from which to hang the bait. The camera not facing south into the sun—all of these factors take time and careful consideration. On this, the first camera, we spent nearly an hour wandering from tree to tree, looking for the perfect setup. Of course, it doesn’t exist, but we found one that we thought was good enough.

(Title) The winter scene is still present in the high peaks of the North Cascades (Above) A baited camera station set-up

John cycles through the pictures. We chuckle at the pictures of the marten, who seems to view the bait as a jungle-gym challenge as well as his dinner. In one set of pictures, he swings back and forth, the bottom of the deer leg clamped in his jaws, his body hanging straight down below—the marten and bait swinging freely. In another he has climbed on the bait, and hangs upside down, looking back at the camera. There are pictures of a marten falling, another of him in a mid-air leap. With each picture, the bait gets a little smaller and the marten gets a little fatter. I am pleased by the pictures. The camera at this station is a model that doesn’t allow us to look at pictures in the field and therefore the aiming and placement of the camera is a bit of a hopeful venture. Instead of taking test pictures and looking at them on-site, we are left doing our best to aim by eyesight and feel. These photos just catch the bottom of the bait at the top of the picture and the top of the run pole in the bottom of the picture. We guessed pretty well.
John methodically clicks through hundreds of marten pictures, but then stops. “That’s not a marten,” he says. And then we see on the screen a big, hunched weasel-ish form mounting the run pole against the tree. A lighter stripe contours its side and tells us it is not a small bear, but rather a wolverine. Click, click. “Is that a collar?” John asks. Within a few clicks, there it is. The picture we could only have dreamed of on the first camera setup of the season, after only a week—a wolverine at the end of the run pole, looking up at the remains of bait. And wearing a GPS collar. Chest on display.

A wolverine atop the mounted pole, captured by a baited camera

The marten has already taken the bait down to bone, so there isn’t much left and the wolverine doesn’t stay long, but long enough. Two pictures clearly show her chest pattern and that she is wearing a collar. John scrambles for the trapping supplies and pulls out the laminated photos of the five wolverines captured over the years of the project. Chest photos. One by one we go through them, and there is only one that matches. Xena. Last seen in a trap in the Twisp River three years ago. The batteries in her collar running out about eight months later. There she is, in font of us, looking up at a deer bone near the Cascade Crest. Just a few days ago. Who knew?
Now, there may be a few of you out there who find yourselves saying, “So what?” And I sympathize with you. Not everyone is as excited about wolverines as we are. And you may wonder what a few chest photos really mean, in the larger sense. Is this really more than just the gratification of a few biologists knowing that an animal they touched and collared is still alive?

A chest view of Xena, a North Cascades wolverine, as captured by the baited camera

Well, yes, as a matter of fact. In the larger sense, this is really cool. You may have heard of mark-recapture studies. You usually hear about it in terms of rodents or other “expendable” creatures. The idea is that you set up a trap grid, and you mark each critter you capture, so that if you recapture it, you know. In my personal experience, this was live traps set on a grid, and metal ear tags put in the ear of every animal—mouse, vole, wood rat—we caught. Through the wonders of statistics, an arcane magic, scientists smarter than I are able to produce truly insightful conclusions about the size of a population, its fluctuations, and how much its individuals move around. Think of this on a bigger scale. A camera station as a “capture.” The unique chest pattern as the ear tag, if you will. And maybe, just maybe, you begin to see the wonder and beauty of this technique.
I will say this, too—I believe I speak for most biologists when I say that a hands-on capture of a rare creature is a truly wonderful, once-in-a-lifetime experience. But there is the little voice in the back of your head questioning if the intrusiveness of the procedure, whether the effect on this one, living, breathing, animal, justifies the benefit of the data we will receive. In effect, we trap, ear tag, and collar a wolverine because we hope that the inconvenience and intrusion into its life will help the species as a whole. And although we revel in the personal experience, the musty smell left on the fingertips, we hope, for the individual’s sake, not to have to do it again.
Not that there isn’t a place for trapping. A wolverine tracked by satellite gives biologists an unparalleled insight into how the animal moves, traverses its territory, and uses various habitat types. It also provides the opportunity to pinpoint a den location.
But the questions are more general for monitoring an overall population. How many animals? Where are they? How long do they live? Are they reproducing? These are the questions that, we hope, can be answered by less-intrusive methods, such as baited camera stations.
Out there, right now, in the mountains of the North Cascades. There are baited camera stations waiting. A wolverine walks up, experiments with the run pole, and takes a look at the bait. The camera clicks away. Mildly disgruntled, perhaps annoyed, this wonderful, mythical creature lopes away, having never been touched by anything other than the flash of a camera. And that’s the true beauty of this brilliant, silly idea put forward and acted upon by a wildlife biologist and her crew in southeast Alaska, and now being put to use in the North Cascades.
Xena—right there in front of us. Three years later. Captured, so to speak, without ever having been touched.

The Author – Daniel Harrington

Daniel Harrington is an itinerant wildlife biologist who has stumbled from seasonal job to seasonal job for the last fifteen years or so. He has held addresses in twelve different states, and gained experience working with raptors, songbirds, Canadian lynx, northwest amphibians, and now wolverines. In addition to a degree in biology, he holds a degree in English/writing, and has been published in several newspapers, the Methow Naturalist, and Oregon Literary Review. He also author’s a blog.

Studying Wolverines in the North Cascades

US Forest Service employees and volunteers from the Methow Valley Ranger District, with direction from the USFS Pacific Northwest Research Station, have been trapping wolverines in the vicinity of the Methow Valley for five years, and have gleaned valuable information from GPS collars placed on five different wolverines. Little is known about North Cascades wolverines, and they are an extremely difficult animal to study. This study—the only study of its kind in the Pacific States—seeks to understand the size and dynamics of the wolverine population in these mountains in order to estimate the size of the population, potential threats, and any management implications. The North Cascades appear to provide an “island” of wolverine habitat, and historical records indicate that wolverines were extirpated from the area in the middle of the century and have only re-established a steady population in the last twenty years or so. Therefore the genetics and gene flow of this population is of particular interest. In order to expand and build upon the data already provided by trapping, this winter we begin establishing baited camera stations and snow-tracking wolverines, hoping to find and identify additional individual wolverines in the area.