Arriving at work on a morning this week, I was asked “how do you feel about following some wolverine tracks today?” The good news was that we had definite evidence of a wolverine visiting one of our trap sites, the bad news was that the trap was closed when the wolverine swung by. Martens are a challenge for us–in this case one was already in the trap, probably munching on some bait, when the wolverine passed by. At about the same time another wolverine had visited a trap at Harts Pass and found it closed, too. That one was closed because of some technical difficulties with the radio telemetry that tells us whether the trap is open or closed.
Despite our disappointment (getting a GPS collar on a few wolverines is the goal for the winter, after all), there was something we could accomplish. Believe it or not, we had a chance to know exactly who this wolverine was.
Technology has had a profound effect on the study of wildlife. GPS and GIS allows wildlife biologist to see the location of collared animals from the comfort of an office chair. Pit tags allow us to know the identity of animals (salmon, bats, and even beavers) as they pass by readers along rivers or at cave entrances. GIS allows biologists to see a wide variety of maps that catalog forest type, soil type, elevation, and about as many others variables as you can imagine. Batteries and GPS units continue to get smaller, allowing the use of GPS tracking on smaller and smaller animals. And then there is DNA analysis.
Believe it or not, the goal of our tracking the wolverine on this day in January was the hope that we would find… scat. It used to be that the only reason biologists were poking and prodding at these basic bodily functions was to discern the peculiarities of diet from what passed through the intestine. But now there’s something else. DNA.
It seems that when an animal (and that includes us) takes a shit in the woods, there is a trace of intestinal cells that slough off in the process and find themselves lingering on the surface of scat. These cells, when the scat is properly collected and delivered to a lab, can be teased off and analyzed, giving the DNA footprint of the animal. Species, sex, and even individual can be identified from these samples. It’s pretty amazing.
Ten years ago, I was in this area tracking Canadian lynx during the winter. I was paid to carry a heavy, accurate GPS unit to record the trail of the lynx and any associated behaviors. One of the things we did was to collect scat and hair as we found them. This was in the early days of this lab technique, and the lab biologists were surprised and encouraged by what they could tease out of our samples. Now there is a movement (no pun intended) to use hair and scat collection as a means of monitoring otherwise elusive wildlife populations. Like the wolverine.
Although I had once seen a snowed-in wolverine track during my lynx-tracking days, this was my first opportunity to spend time with a good track. It was a lot of fun. For those of you who are trackers, aspiring trackers, or just interested, here are some of my photos and observations:
The track itself seemed pretty distinctive, if you’ve looked at a few tracks in the snow. The feet are large compared to the size of the animal, so you get large tracks with a relatively small stride and straddle. You might confuse them with a wolf, but the stride is much shorter, and the same for a cougar. And the track pattern is different.
If you can see toes, it is easy. The weasel family has five toes that show in a track, and the middle three toes are closer together than the outer two, giving what is called a 1-3-1 pattern to the toes. A picture might help:
Note also the the claws clearly show in the track, which means it is not a cat. The marten is in the weasel family, and could be confused with a wolverine, I suppose, but the marten track is much smaller, whereas the wolverine track was about the size of the palm of my hand (according to Halfpenny, the wolverine averages a 4″x4″ track, while a marten is 1.75″x1.75″). The toes also seemed much more distinct than in a marten track, as if the marten has furrier feet. Another picture with my snowshoe and foot for scale:
Note also how the heel of the wolverine seems to lay down into the track, making it look elongated. We were lucky with snow conditions–there was a little bit of new snow on top of a hard, older layer. These pictures, taken where there was less snow under the trees, really gave a good look at the pattern of the foot, as opposed to in the open areas, where the snow obscured more of the detail. A good lesson in tracking is to always follow an unknown track for a ways before deciding what it is–it may look very different at the roadside than it does further along, and it is better to develop a mental image of the usual track pattern, size, and shape and to morph these into an “average” track and pattern in your head.
And before we move off into the snow, here’s a couple of photos of John, my supervisor, creating some “wildlife paperweights” as he calls them. The red stuff is a spray-on wax that keeps the plaster of paris from melting the snow (and therefore the track)… the wax is commercially available, and the plaster is very available, and you end up with a cast of the track. His were slightly soft after a couple of hours, but ready to be moved.
The wax also seemed to make the tracks show a little better in these pictures…
Moving out from under the tree cover and into some deeper snow, I was surprised that the tracks didn’t show more drag from the wolverine’s body. Although the tracks were a little messy (kicked snow, dragged toes, etc) they were cleaner than i thought they would be. This can be different in different snow conditions, though.
Since these tracks I have seen some in powdery snow at Harts Pass, and there was a bit of a body trench involved in those tracks.
Represented here are the two track patterns I noted while following this wolverine. They are standard track patterns for the weasel family, and I believe are referred to as the 2x and 3x patterns. I was surprised, in following this critter, how often and easily the wolverine switched back and forth between these two patterns. There didn’t seem to be much difference in the speed of the animal, although in my mind the 2x track seems more suited to a faster travel. The real key to knowing this is to see the length of the space between track sets (the stride) increasing. But the stride on the tracks I saw seemed comparable in the 2x and 3x patterns. Also of note is that the animal seemed comfortable changing the lead foot, so sometimes the tracks were slanted right (as in my representation to the left) and sometimes slanted left. It’s fun to know, too, that the 2x pattern is actually 4 feet landing in each set of tracks… the lead feet have already left the track when the hind feet land in the same spot.
Some more photographs:
A 2x track pattern in the snow.
A 3x track changing to a 2x track.
“Being a weasel” … he/she was checking every tree bole on the way up the hill. Looking for squirrels? hares?
The wolverine crosses the river. Notice the track pattern and how the lead foot has changed from the foreground to the most distant tracks, and that there are a couple of 2x strides before going back to 3x…
In the end, we got what we were looking for. One team backtracked and the other forward tracked, and although neither group collected any hair (DNA can also be gleaned from the follicles when hair get pulled out of the animal), each team did recover a turd. A couple of wolverines have been trapped in this vicinity in recent years, and DNA is taken when they are trapped, so when the results come back from the lab we’ll know if the animal we were tracking was one that had been caught before, and if so, exactly which one. Pretty neat.
What the Owl Knows 