Finding F8


Matthew Scrafford
Wolverine Conservation Scientist


Early-Career Scientists Research fellowships Wolverines



We were fully aware of our intrusion into the still winter forest as we traipsed along with the loud clatter of our snowshoes.

Branches breaking and grouse flushing, she would surely hear us coming, but we needed to keep pushing ahead to find F8 and her den before sunset. It was already 6:00 pm when we came to a forest clearing. The sun was beginning to fade from us behind the dense spruce forests, the resulting shadows an unwelcome change from the pleasant March sun. I raised the telemetry antenna above my head. The sound that came from the receiver caused my heart to race. The signal was coming in loud and clear, F8 was no more than 500 metres away.

It was early March when we first live-trapped F8. The trap was on the crest of the escarpment running east to west above the town of Rainbow Lake, Alberta. To the north of the trap lay the beautiful and bountiful Hay-Zama Lakes. To the south was Alberta Highway 58, making its last twists and turns before terminating its westerly course in town.

We immobilized and radio-collared F8, taking tissue and hair samples for DNA and cortisol testing.When we weighed her, we noticed she had teats and was lactating.F8 was a mum. Excited but concerned, we quickly reversed her immobilization drugs and opened the trap so she could return to her kits.
A few weeks later the trap we caught F8 in was set off again. We grabbed our gear and made our way down the dirt roads and trails that lead to the trap. We were no more than 20 metres from the trap when we heard the distinctive growl of a wolverine.

Excited, I dug through my bag for the VHF receiver. If this was a recaptured wolverine with a radio collar, I should be able to hear the radio collar's unique VHF signal. Switching through the channels, a ping exploded from the receiver when I got to F8. She was back, along with weeks of GPS data logged in her collar that might indicate to us where she was denning.
The father of F8's kitsWolverines practice intrasexual territoriality, which means males have distinct home ranges from other males, and females having distinct home ranges from other females. Within the expansive home range of a male wolverine (~1,500 km2), 2-4 females roam.

Relentlessly travelling the boundaries of his range, a male is always on the lookout for intruders and something to eat. Come summer, the male mates with his females, and, if all goes as planned and the females are healthy and did not give birth the previous year, 2-3 kits are born to each in mid-February. M7, a burly 16 kg wolverine, full of spunk and grouchiness, is likely the father of F8's kits. We think this because of how closely his movements follow those of F8. M7's son, M8, follows the movement paths of M7 almost exactly, and the two are often seen together at traps.
Wolverines and late-spring snowResearchers have found that wolverines den where there is snow late into the spring and where there is no human development. In the mountains of western North America, deep snow (>1 m) covering dens dug into high-elevation avalanche debris and boulder fields provides kits thermal protection as well as isolation from lower elevation predators (e.g., wolves) far into the denning period. Researchers believe wolverine kits need this protection until they are strong enough to leave the den to hunt and scavenge with their mother (wolverines are typically weaned around May 15th). As a result of these relationships with late-spring snow, the threat that climate change poses to the persistence of snow in the spring has been used as the rationale behind the proposed listing of wolverines on the Endangered Species List in the United States (for more information see, while in Canada they have been assessed as Special Concern due to increasing industrial activity and road access to their remote habitats. Human development could disrupt den sites and create access (via roads) to dens for predators. Wolverines in northern Alberta exist year-round in the same industrialized habitats as wolves. Additionally, northern Alberta rarely has deep snow through to the time kits are weaned. Therefore, we are unsure how and where wolverines den in northern Alberta's boreal forests, which is crucial information to have if we are to conserve this rare species. For these reasons and many more, we were very keen to see where F8 was keeping her kits.

Downloading GPS radiocollar data from F8

I set up the remote-download equipment and waited anxiously for F8's GPS data to be transmitted from her radio collar to my computer.

The search for F8's denWe got back to camp that night and plotted F8's GPS data. We could see she was using a 200 km2 area. We also could see that she was in her den a lot. Nearly 75% of GPS position attempts (fixes) were missed each day by F8's radio collar. This meant she was in her den and the radio collar could not get a clear view of the sky. When we looked at the GPS data closely, we saw that after we released her from the trap she moved east along the escarpment. This movement ended where there were five GPS points stacked exactly on top of each other, called a cluster. In other words, F8 spent nearly 10 hours in this spot immediately after we released her from the trap. I figured this was the best location to start our search for her den.
The next day, Scott Seward, Lenore Stone (Alberta Conservation Association biologists), and I drove north towards the escarpment and the cluster. As we got higher in elevation, I asked Scott to park the truck and I climbed the bank to get a clear signal and view of the landscape F8 had been using. Boreal forest, in a mixture of poplar, spruce, fir, pine, and muskeg, stretched as far as the eye could see. Besides the escarpment we were climbing and the Hay and Chinchaga River valleys, the landscape was extremely flat. I switched through channels on the VHF receiver until I got to F8's and raised the antenna to the sky. I could faintly hear the ping of F8's VHF signal. I walked down the bank a few meters, raised the antenna, and once again heard the ping.

It sounded like she was far away, maybe a few kilometres, but in the general direction of the cluster we wanted to visit that day. I could not believe our luck. Finding wolverines in the boreal forest with VHF equipment is difficult from the ground. Dense forests weaken VHF signals such that a radio collar might only be detectable from 2-3 km away. Although searching for VHF signals from airplanes or helicopters is preferable, these flights are expensive, and consequently, infrequent. I went back to the truck and took out the map. We drove to a starting point for trekking that was about 2.5 km from the cluster.
Because March mornings still get very cold, we dressed warmly and hiked to the cluster with snowshoes. As we hiked, I would periodically raise the antenna to gauge the VHS signal's strength. The signal still sounded weak. Could that be because she was in her den? We came to an open marsh. Willow thickets lined the edges of a beaver pond and a poplar ridge created a backdrop to the east that the sun was slowly cresting. I raised the antenna and heard a much stronger signal. This signal, however, came from the south, and the cluster we wanted to visit was to the northeast. As originally planned, we decided to visit the cluster instead of chase her signal. I put away the VHF antenna and concentrated on hiking, which I was happy to do as I had already fallen a number of times while negotiating the cables and antenna through the bush. We arrived at the cluster but noticed no fresh sign. We could see F8's tracks from a few weeks ago, melted out and looking more like bigfoot tracks than those of a 9.7 kg wolverine. The three of us split up and canvassed the area.
I find it fascinating to visit these clusters and think about what the wolverines were up to. The feeling I get is analogous to visiting sites where famous speeches were made or battles waged. I use my imagination and biological knowledge to piece together all that occurred at these clusters. I imagine a wolverine digging up a moose carcass, grunting like a pig, while the grey jays and raven look on amused and hopeful for some scraps.
I heard Scott and Lenore call to me. Scott said I should come check something out. Scott had found a mound that was created from the root wad of a fallen tree. I could tell the mound was old, covered in moss, grasses, and the remains of hundreds of cones harvested by squirrels in the trees above. At the base of the mound was an opening no larger than a dinner plate. We knew this had to be a den for something at some time, maybe a fox, fisher, lynx, or a small black bear. Although not F8's current den, it could be her natal den (where she was born) or a den where she had reared kits in years past.

We searched the area more for scat and hair, took some pictures, and then decided to directly follow her VHF signal. We went back to the beaver pond and I checked the signal again... she was in the same spot to the south.
We were currently north of F8's VHF signal, but because of the danger of river crossings that would have to be made in our trek towards her current location, we decided it was best to approach her VHF signal from the east. We walked back to the truck, drove around, and had a late lunch. It was 3:00 pm when we started walking west towards her last known location. Our trek started on a pipeline, but because it was grown in with willow and poplar, we decided to instead walk through the forest. We hiked for 2 km and then took a rest. I climbed up a dirt bank along a winter road created by bulldozers and raised the antenna into the air, but F8 was nowhere to be found. Disheartened, I questioned our chances of finding her den with the day's light beginning to fade. The crew convened and decided to continue west, but for no more than an hour.
We continued our trek as our legs became increasingly heavy from the effort of snowshoeing. Twenty minutes later at the intersection of a cutline and pipeline I hooked up my telemetry equipment. Before I even raised the antenna into the air the signal came booming in, F8 was no further than 500 metres away. We took a bearing of her location and walked towards it as slowly as possible, looking for signs of F8 and trying to dampen our noise. Soon thereafter we came upon fresh wolverine tracks, perfectly visible in a thin layer of snow on top of the crust created by the freeze and thaw of March days. We were getting close! I raised the antenna again and pointed it west towards our initial bearing but F8's signal was barely discernible. Perplexed, I scanned to the north and the signal regained its strength. Maybe it was getting jumbled by the dense forest? We continued 100 m and listened again, now F8 was behind us! No more than a few hundred meters away, F8 was circling us, darting through the dusk-lit forest with the stealth and quickness that wolverines have evolved since the Pleistocene. The realization that she was making rapid circles around us in the shadows caused my heart to race. We figured we had flushed her from her den and that she had heard or smelled us coming hours ago. She probably stayed with her kits until her instincts told her she needed to divert us. I knew her signal was not going to help us anymore so I put away the telemetry equipment. We now had to backtrack.
We found some fresh tracks that diverged in two directions and split up. Fully aware of our company and feeling vulnerable as the light of the day waned, we scanned the forest for a glimpse of F8. A few minutes later, Scott said I should come see something. Scott and Lenore were staring at a mound with excited but nervous looks on their faces.
Wolverine tracks were leading into a tiny hole at the base of down trees. A few wolverine scats were in the area as well as some day beds.
A root wad had formed when four different trees fell in opposite directions, lifting the soil into a mound. On top of the mound was thick moss and approximately 20 cm of snow. We took pictures and notes.
I got on my knees and crept towards the den opening. I immediately heard the kits crying out (click on the video below - can you hear them?).

I estimated there were two kits based on the sounds. At this point in their development, they could not be bigger than 1-2 kg. Looking into the entrance hole with a flashlight, all I could see was dirt and roots, as the tunnel turned immediately to chambers high in the root wad where the kits were likely staying. Covered with moss and lots of dirt, this den surely provided kits thermal protection. This protection was afforded mostly by the moss-covered root wad, not the snow, so the theory that wolverines need a metre of snow until mid-May to raise their kits might not apply to wolverines in northern Alberta. Additionally, this den was not isolated from wolf populations by any means, an interesting contrast to wolverine populations in the US that breed at higher elevations. We took a few more pictures and left the same way we came, so as to minimize our disturbance of the kits and mother.

In mid-April I revisited F8's den. Wolverines have natal dens where they give birth and maternal dens that they move the kits to once they are bigger. It is not fully understood why wolverines move their kits to a new den, but conditions inside the den (e.g., humidity) likely play a role. In addition, a safe den for the kits is a top priority, and so intrusions in or near the den could also cause a move. When we returned to the den site, I could immediately tell that it was no longer in use because of the lack of wolverine signs. I put my ear to the den opening and there were no sounds from the kits. I felt guilty that we may have caused the wolverine to abandon her den and dig up another one somewhere else, and a bit overwhelmed at how impossible it seemed to study this elusive creature while minimizing disturbance. However, upon closer inspection, I could see that the snow had completely melted off the den's roof. The snowmelt exposed a few very small natural holes in the roof that probably seeped water and caused F8 to move her kits. We set up a motion-sensor video camera at the site and F8 showed up the next day.

She is likely denning in the area, but our attempts to find this new den have so far been unsuccessful.

This isn’t just a story about scientists collecting information to add to their datasets. As far as we know, this is the first wolverine den to be found in northern Alberta. The area’s abundance of wolves and lack of late-spring snow, in addition to the den's placement near industrial infrastructure, goes against what researchers have traditionally assumed is ideal wolverine denning habitat. Yet we captured 24 wolverines in the Rainbow Lake area this first year, and seven of them were lactating. Although climate change certainly threatens all North American wolverine populations due to extreme summer heat, the threats to their denning ecology might not be as severe. Maybe wolverines are even tougher than we think. For their sake, I hope that they are.

This research would not be possible without the support of:- The W. Garfield Weston Foundation Fellowship through Wildlife Conservation Society Canada- The Alberta Trappers Association- The Alberta Conservation Association- The Dene Tha First Nation- Husky Oil- TD Friends of the Environment Foundation- The Wolverine Foundation- Safari Club International - Northern Alberta Chapter- Strategic Oil