Where Wolverines Are Born

When I set out last week with the coordinates for F3’s den programmed into my GPS and the site marked on a series of paper maps, I couldn’t shake a feeling that approached sheer giddiness. The opportunity to examine a wolverine den site is akin to winning some kind of wildlife biology lottery; the dens are as inherently rare as the species, and the dens that are known to science are even fewer. Only around 15 have been documented in the Lower 48, leaving a huge gap in our knowledge of reproductive dynamics. For years, F3 had failed to den, and the instruments on our other female, F133, had died, so we had no way of knowing whether she had had kits. When F3 evidently did den this year, I was ecstatic, but I was also in Cambodia. I was starting to think that I would never have a chance to investigate a den site. When I made it back to the Rockies earlier than expected, in August, getting to F3’s den site was one of my priorities.

A crew visited the den in May, when the snow was still on the ground, and some of the same crew members had gone back once the snow melted, in July, to investigate the site and to see if they could find scat samples. The spring crew hadn’t seen the kits or verified their existence, so however strong the circumstantial evidence, we couldn’t be certain that the site was a den instead of a food cache, and we couldn’t say with confidence that F3 and M57 had reproduced. The July crew had looked for latrine sites, which are proof that a site was used as a den. And the crew found them in abundance, pulling out a number of scat samples for analysis. They hadn’t gone digging for the kits or attempted to instrument the babies in May because of funding constraints, so the scat samples, in addition to confirming that this was a den site, also offered a chance to identify new individuals and perhaps determine their sex.

The important work had already been done, and my own trip was half fun and half pilgrimage. I wanted to visit the place where F3 had – presumably – brought her first kits into the world, and I wanted, after nearly a year away, to be back in mountains that form some part of the mental and emotional landscape of home.

The route into that landscape followed a trail for a while, and then cut away from the trail and up gentle south facing slopes, warm with late summer sun and the scent of dust and pine. At the crest of a pass, the world dropped away, the slope plunging steep and precarious into a narrow pine-cloaked valley that swept back to intersect with the endless marching peaks of the high Absarokas. These north-facing slopes were utterly different from the warm hills I’d just left; I had to edge my way down, dancing between tree trunks for support, the force of gravity and the angle of the pitch propelling me towards freefall. The trees were thick, the shade dense, the temperature so much cooler that I paused to put on my jacket and hat.

Possible wolverine scat under a log, about 0.4 miles from the den site.

As I crouched to pull out my hat, I noticed a huge pile of scat under a log near my feet. I was still a half mile from the den site, but the scat was definitely carnivore and seemed mustelid. It was a bit small, but they were kits, after all. I hadn’t been expecting to collect samples but I did have two ziploc bags on hand, so I shoveled the scat and a large chunk of fur into the bags, GPSed the location, and continued to slide downhill through the dense, cold forest and small open meadows. These meadows were saturated – with streams, with flowers, with warmer patches of sunlight, and with the same breathless silence that hung over the trees. The quiet was ancient and deep and almost tangible, so that I felt like I was diving down and further down through a substance like water, into some other world.

Among all the trees, I wasn’t sure how I would ever find the actual den site, but as I crossed another meadow and stopped to look across the stream that drained it, a patch of pink fluttered from over the water. In May, the crew had tied flagging tape to the tree branches directly above the six entrances to the den. Now, in August, with the snow melted, the tape hung fifteen feet overhead. Beneath the tape, F3’s excavated snow tunnels had led down to cavities sheltered by fallen trees. I’d found the tape, and I’d found the den.

A wolverine's-eye view of part of the den site. The chambers were beneath the downed trees. Note human for scale, and pink tape in tree overhead. This marks the approximate depth of the snow in May.

The crew had already collected all the samples, and I spent a long time simply exploring the area and then sitting and basking in the vast silence. The multiple den entrances had sprawled across an area of approximately 120 m²; the tunnels were probably connected beneath the surface. Beneath the largest of the downed trees on the ground, a hollow against the root ball seemed to have served as one chamber, with two others located among the branches further up the trunk. Against another downed tree, another flattened area between branches suggested a chamber as well.

One of the hollows that was part of F3's den site.

I tried to imagine the family down under the snow in a world of compressed ice, first as newborns and later as more active babies. Did F3 dig new tunnels as the kits grew, or had she constructed the whole network at once? Did she move them from place to place as waste accumulated? At what point did the babies begin to move around through the tunnels on their own? Or did they simply wait, curled up around each other for warmth, where F3 left them when she went out to forage? Had M57 come down here as well? The crew in May had heard his signal and found his tracks crossing their own ski trail; he had traveled directly to the den from the distant location where the crew had heard his signal earlier in the day. If he had gone into the den, what did he do while he was down there? Did he bring them food? Keep an eye on things while F3 was out? (She hadn’t been in the den the day the crew visited.) Play with the kits, add his warmth to theirs, wrestle with them to toughen them up for the outside world? When had they left this place, and did they ever return?

I looked up from the logs, scanned the trees, but everything remained still – no sign of wolverines, or of anything else. The most important ecological question – why here? – remained unanswered, but my personal reasons for being there had been more than fulfilled. I was overwhelmed again by the extraordinary stillness of the place. Later, it came to me that the meadow was suffused with a sense of peace that goes far beyond our normal conceptions of that word – the peace of the Wild, a peace that is so powerful because of its utter indifference to human concerns or moral order, a peace that is edged with on-going loss and ferocity and struggle that are, nevertheless, somehow more acceptable and less alien in places like this. It was, I hoped, a good place to be born a wolverine, and I was profoundly grateful to have seen it.

Gulo Dads

Back in the days when the world believed nothing but ill of wolverines – that they were nasty, smelly, anti-social animals intent on wreaking havoc on various human enterprises – male gulos had a reputation as infanticidal villains who would kill their own kits in the den. Scandinavians reported instances of male wolverines entering dens in their territories and killing the babies, which made no sense from an evolutionary perspective, but which fit the wider perception of the species.

Not until the Glacier National Park project did that perception begin to change. Jeff Copeland, Rick Yates, and the project volunteers observed male wolverines visiting dens – but apparently just to socialize with their families (author Doug Chadwick speculates that they might also bring their mates food, but this hasn’t been observed.) Males in the Glacier study also traveled with their juvenile kits of both sexes, showing them how to survive in a harsh landscape before the kits dispersed. This was gratifying to wolverine lovers, and it also made a lot more sense to those who believe in a rational universe. Why put all of the effort into reproducing if you’re just going to kill your own offspring? A caring gulo dad made much more sense than a homicidal one. Observations of kit-killing in Scandinavia may have involved males taking over territories of other males that had died; the destruction of young by interloping males is fairly common among mammals, and would make sense for gulos in Scandinavia, where hunting levels have traditionally been high and wolverine turnover through a given territory would also have been high. Towards their own kits, however, wolverines appear to be attentive fathers.

The wolverine’s change in status from bad dad to good was welcome, and the new narrative has caught on quickly. It was highlighted in the PBS documentary and in Doug Chadwick’s book, and now the wolverine has made Scientific American’s list of the top eight fathers in the animal kingdom. I’m pleased, but I can’t help but reflect on the fact that this new animal superdad comes at a convenient time in American history. He and the mate share duties and spend some quality time together (M57 and F3 seemed to be traveling together frequently during 2009 and 2010; she came to visit him when he was in one of the live traps), but most of the time they’re busy independently roaming around and making a living. He’s not an overbearing patriarch, he’s a cool guy who hangs out, takes the kids out on adventures when mom is busy, and maintains a meaningful relationship with his offspring during their adolescence.  I’m not sure that Americans of a century ago could have appreciated this particular picture of the nuclear family as a constellation of individuals maintaining their independence while also retaining family ties. But to those of us who wish our dads a happy father’s day via google phone from Mongolia, for example, or spend months away from our male companions in order to pursue our work or our research, or insist on equal childrearing duties – or who simply want our mates to be incredibly badass and rad – the picture of wolverine family life seems suspiciously familiar.

So this comes a little bit late, but Happy Father’s Day to all of the gulo fathers out there, and thanks for the inspiration. The wolverine life cycle is marked by American holidays; kits are born around Valentine’s Day and weaned around Mother’s Day, which is neatly symbolic. We can’t say this for sure, but we can imagine that by Father’s Day, wolverines are beginning a summer of hanging out with dad – that as I write, M57 and his kits are cruising the snowfields at the cool, shaded bases of cliffs somewhere in the Absarokas, that the kits are chasing each other and wrestling until M57 stops suddenly, catching the scent of something beneath the snow. That the kits are attentive now as he starts to dig, unearthing the carcass of a goat that slipped from the cliff back in February. That they will remember the strategy of following cliff bands, the scent of meat eight feet below the surface, and the particular way that he digs it out, and that these things that their dad teaches them will help them survive in a rough world.

The Den

Last week, a small crew on skis set out into the high mountains of the Montana wilderness. They were headed into wolverine country, their objective a series of scattered points close to treeline. The points had been obtained during telemetry flights in April, and they indicated that F3, a five year old female wolverine, was restricting her movements to a small portion of her usual range. Under normal conditions, F3 might be found anywhere within an approximate 300 km² sweep of rugged country. Over the past several weeks, however, she had limited herself to a few drainages in close proximity to each other. Her behavior unleashed a wave of excitement among the wolverine crew who had been tracking her since 2007; restricted movement is the classic indication that a female wolverine is in a den with kits.

Determining F3’s reproductive status has become an annual springtime ritual at the Absaroka-Beartooth project, fraught with trepidation, surges of hope, and, inevitably, disappointed resignation to the fact that, once again, the project’s sole instrumented female wolverine has failed to produce kits. We’ve been engaging in this ritual since F3 was first captured in 2007. For the first two years, she was young, and, as far as we knew, there was no male in her territory, so the absence of a den in 2008 and 2009 wasn’t such a surprise.

F3 in 2008, captured by an automatic camera at one of the project's live traps.

Then, in spring of 2009, the Wildlife Conservation Society’s wolverine project took charge of a young male that had been accidentally caught in a bobcat trap in Idaho. WCS released the wolverine, M57, in Montana, and he promptly headed for F3’s territory. We knew that F3 and this male – notable for his white paws and his unprecedentedly relaxed attitude when captured by the project’s live traps – were traveling together throughout 2009, and the tension over F3’s status in spring of 2010 was palpable. For the first time, we had real grounds to hope for babies.

The question was especially urgent for the project because the work done so far had provided no evidence of reproduction in Yellowstone or the ranges immediately to the north, south, and east. In fact, those ranges seemed strangely vacant; the habitat appeared good, but the wolverine population was sparse even for a rare carnivore. Over the course of five years, the project had documented two immigrants to the study area – M57 and a female, F133, who was born in the Gallatins and who traveled across Yellowstone to take up residence south of the park. But there had been no births. This suggests that, at least in Yellowstone and its immediate surroundings, the wolverine population currently depends on dispersing wolverines from further to the north and west. With only a single den documented in Wyoming – in the Tetons – the data also suggest that Wyoming’s population might rely on input from populations in Montana. And with talk of reintroduction following M56’s trip from Wyoming to Colorado, the need for a healthy region-wide meta-population, with as many interconnected nodes of reproducing wolverines as possible, became even more urgent. Any further understanding of reproductive dynamics and denning characteristics – not to mention the sheer and simple fact of more wolverines on the landscape – would be invaluable.

In 2010, a series of telemetry flights eventually indicated that F3 wasn’t denning. We caught her in March of 2010 and were finally able to determine that she was not nursing, although she and M57 were still traveling together. Disappointed, we held out hopes for 2011, but by now the project was officially over and finding resources to keep it going was becoming more and more challenging.

This season, F3 went into the trap early, in January, and the crew noted that her teats were enlarged –  a real reason for hope. The weather remained ferocious throughout the spring, making flights difficult, but when a series of telemetry points finally came in after flights in April, F3’s apparent localization added further evidence to the argument for kits. Finding proof, however, was necessary, and the mission was urgent: wolverine kits leave the den in early May, and the dens themselves, dug in the snow, are ephemeral and nearly impossible to identify once the snow is gone. From the time the points came in, the crew had approximately two weeks to get to the area and figure out what was going on.

The trip in took three hours of skiing, over a steep pass and through heavy snow. At the outset Jason Wilmot, who was leading the trip, listened for F3 and M57 and picked up M57’s signal to the south. There was no indication that F3 was anywhere nearby, and the first point that the crew reached yielded nothing. Jason and the crew pressed on to the next point.

Here, at the pass, they picked up tracks, and then more tracks, and then an explosion of tracks. This, too, was strong indication of a den, and sure enough, backtracking the prints, they found a hole. And then another one. And another. Altogether, the crew discovered six holes in the snow, some apparently linked beneath the surface. The tracks were melted out and the crew were unable to determine whether they came from multiple animals, let alone animals of different sizes. But the evidence for a den and kits was strong.

The crew had already made the decision not to instrument the kits – without the funds for flights to monitor them, it would have placed unnecessary stress on the animals – so they didn’t dig to see if the babies were underground. Instead, they collected DNA samples from the tracks and the entrances to the holes. They listened for F3, but she was still absent. If there were indeed kits, the family might have already left the den permanently, but F3 might just as easily have been out on a foraging run, and the kits could have been curled up in a chamber in the snow beneath the crew’s feet, pondering the strange vibrations of skis and human voices.

Before they left the site, Jason listened again for M57. The signal came in, and it was loud – M57 was somewhere nearby. Employing a trick that wildlife biologists use to determine exactly how close an instrumented animal is, Jason removed the antenna from the receiver and held out the cord with its metal end. If an animal’s signal still comes in without the antenna, the animal is really close. M57’s signal continued to boom in. He was right on top of the crew, probably watching them from somewhere in the trees. As Jason and the remainder of the crew skied out, they crossed M57’s tracks coming into the basin; the wolverine tracks were overlaid on the ski tracks of crew members who had already skied out. From his position far to the south earlier in the day, M57 had traveled directly to the den site. This was further circumstantial evidence that this was indeed a reproductive den, and that M57 was coming to check in on his mate and offspring – a pattern detected on numerous occasions by the Glacier Park and WCS projects.

Without having seen the kits, we can’t confirm that F3 and M57 reproduced. But the evidence is good. From here, we’ll use genetic analysis to try to determine if there are kits and if so, how many. We’ll return to the den site in the summer to gather more DNA samples. If there are kits and if they survive the summer, they are likely to remain within their parents’ territories for the next year, and F3 and M57 are likely to show them all the good foraging spots – including the project’s live traps. We may have the opportunity to capture and examine the kits this winter, to at least determine sex. If we find the funds, we may be able to instrument them and monitor them as they approach dispersal age. This could provide crucial information about connectivity among the different populations, and the extent to which southern populations really are dependent on dispersers from Montana. Overall, it’s exciting and hopeful news for the project and for wolverines at the edge of their range.

The Absaroka Beartooth Project: Captures

The Absaroka-Beartooth Project report was published two weeks ago, the culmination of a five year project to investigate the status of wolverines in and around Yellowstone National Park. The report could be summarized in a straightforward  way, but as I read it, I realized that a laundry list of statistics wouldn’t do justice to the project’s many facets. I’ve been involved with this project, off and on, since 2006, and I thought it would be more interesting to provide a narrative for each segment of the project. I’m starting with the very basic story of the wolverines that were captured over the course of five years, and what those captures tell us about the status of wolverines in Yellowstone.

Yellowstone National Park is the wellspring of the idea of sacred wilderness in modern American consciousness. Our first national park, correctly or incorrectly, is perceived as a pristine stronghold of our most spectacular and intriguing species, which are supposedly free to function in the absence of human interference, and there to teach us what unfettered nature looks like. So it made sense, following the success of the Glacier National Park wolverine study, that the  investigation of wolverine status in Yellowstone was the next priority for a creature emblematic of the wild.  No one knew anything about wolverines in  Yellowstone; aside from sporadic sighting reports, data on the species was non-existent. The park and its surrounding ranges – hypothetically ideal habitat – were expected to provide one more piece in the puzzle of wolverine status in the US Rockies.

In 2003, the wolverine had been turned down for listing, for the second time, due to lack of data. The Glacier project began that same year,  aiming to fill some of the gaps that prevented the US Fish and Wildlife Service from determining  the wolverine’s situation. By 2005, the Glacier Project was yielding solid information and environmental groups were suing the government to reconsider the 2003 decision. The Absaroka-Beartooth Project began that winter with an initial season of live-trapping. The park was the core of the investigation, but the project extended beyond the park boundaries to encompass the Absaroka mountains and the Beartooth plateau to the east, northeast, and southeast. Complimenting on-going work by the Wildlife Conservation Society in the Montana ranges west of Yellowstone, the project established live-traps for wolverines in locations across the park and its eastern borders.

The Absaroka-Beartooth Wolverine Project encompassed ranges in and to the east, northeast, and southeast of Yellowstone.

In March of 2006, I arrived in Sunlight Basin, a spectacular valley in the eastern Absarokas, to meet with Jason Wilmot and his wife Kate, who were stationed there to monitor traps through the winter and spring.  I’d come to discuss my upcoming summer research on wolves in Wyoming, but the conversation quickly turned to wolverines. Within 12 hours of meeting the Wilmots, I was traipsing up a steep slope, knee-deep in snow, carrying a duffel bag containing a skinned frozen beaver, and listening to Jason as he talked about all the things that made wolverines the most awesome animals on earth. Key among its attributes, for me, was the coincidental information that there was an unstudied population in Mongolia, where – it so happened – I had spent two years as a Peace Corps environmental volunteer. We reached a log-box trap buried in snow, and while I examined a small plaque that stated that the trap and its contents were part of a research project and should be respectfully left in peace, Jason attached the beaver carcass to the back of the trap in hopes that a wolverine would soon remove it.

He and Kate waited through the entire spring, but the beavers in all of the Sunlight traps remained untouched by gulo-kind. While the thought of Mongolian wolverines lodged at the back of my mind and began to germinate into what would become, three years later, a full-fledged project of its own, the Absaroka-Beartooth Project captured wolverines north of the park, and south of the park, but the rugged mountains within the park boundaries and just to the east seemed strangely devoid of the West’s most notorious mountaineer.

By summer of 2006, when I returned to Wyoming to begin my summer research on wolves, the Absaroka Beartooth Project was monitoring two male wolverines, M1 and M2. M1 made his home north of the park; he’d been captured twice over the course of the winter. M2 was captured, once,  in the southern part of the park. Researchers refer to ‘trap nights’ as the number of nights a single trap is open and baited.  The three captures of M1 and M2 represented the fruit of 1831 trap nights in 2006, for an average of one capture every 610 trap nights. In contrast, the Glacier project in its first year captured six wolverines – three males and three females – with an average of one capture every 12 trap nights.

If these numbers fazed him, Jason didn’t give any indication of concern over the course of my wolf research in summer 2006; he continued to talk about wolverines with so much enthusiasm that I became more and more intrigued. In August of 2006, tired of the squabbling over wolves and hoping for a chance to appreciate a species free of the weight of centuries of symbolic feuding, I joined an Absaroka Beartooth project expedition to investigate a cluster of GPS points from M2’s collar. By now, M2 was hanging out south of the park, in some of the most inaccessible territory in the lower 48, and it took two days to reach the site. At dusk on the first night out, a wolverine came into our camp. It wasn’t an instrumented animal, which meant that it was an entirely new wolverine. We were able to extract a viable hair from a snowfield, which later matched DNA from male M4, captured by the project months later in March of 2007. The project instrumented him and located him once in a flight following the capture, but he subsequently disappeared. We still don’t know if his transmitter failed, if he took off for Colorado or Utah, or if he died.

A month before M4 was captured, M1, the project’s first male, was legally killed by a Montana trapper. Then, the week before M4 was captured, the project caught a small juvenile female in the Absarokas north of the park, within M1’s territory. This wolverine was tagged F3, and she is probably M1’s daughter. A female wolverine was legally killed in the same region at the same time; this was possibly F3’s mother, and her death meant that F3 could take over the now-vacant territory. F3 became the center of the project’s hope and attention, a young female just coming into her reproductive years. These four wolverines – three males, one dead and one vanished, and one young female who, despite our hopes, remained stubbornly single and kit-less – were the entire captured population of the project’s five years. Over the course of the project, they were caught seven times – M1 was caught twice, F3 three times. All told, the average capture rate was one wolverine every 750 trap nights.

The enormous effort required to document such a scant population suggested something unexpected: Yellowstone National Park and its eastern borders – huge, rugged country that should have been ideal habitat – lacked a substantial population of wolverines. They simply weren’t there. Yellowstone, the great emblem of all things wild, was apparently missing the wildest creature of all.

Break out the Champagne! (Tentatively….)

The sky finally cleared enough last week to get two flights into the air, on Wednesday and Saturday, and F3 was in the same location for both flights!

We’ve tentatively concluded that she is indeed localized and that this, along with evidence of pregnancy when she was caught in January, suggests that she has kits. The pilots observed a large number of tracks in the vicinity of the signal as well. With wolverines, assumptions can get you in trouble, so I’m trying not to invest too much in the idea of these kits until someone has actually seen them. But the evidence points to a new family of wolverines in the Rockies.

A field crew will ski in to investigate and perhaps set up a camera at the site. We probably won’t instrument the kits; the project is currently at a low budgetary ebb and we lack the funds to regularly fly and monitor kits, which would be necessary to gather the data that telemetry could provide. This is unfortunate, since dispersal is one of those critical parameters for understanding population dynamics, especially in this tiny population node at the very edge of wolverine range. A site visit and a camera will allow us to determine how many kits F3 has, and perhaps their sex, and may even offer some information on whether M57 is visiting the den, and how often.

I am simultaneously thrilled – we’ve been waiting years for F3 to have babies – and a little disappointed – I am currently out of the country and won’t be able to participate in the den visit. But the disappointment is all selfish, and the excitement is absolutely overwhelming.

Further exciting gulo news came out of Oregon today – after researcher Audrey Magoun tracked a wolverine in the Wallowa Mountains of eastern Oregon last week, her camera traps captured images of two individuals in the same area. Audrey and her husband have reset the camera stations to photograph the animals in a way that will allow them to determine the sex of the two animals.

After years of sighting reports from Utah, WCS did surveys last year and picked up tracks in the Uintas; the tracks looked like wolverine tracks, but they couldn’t confirm the ID. This winter, a Forest Service biologist found and documented a set of tracks in the Uintas as well, and the photographs suggest that Utah does have at least one wolverine after all. Where did this wolverine come from? This is one of the reasons we need the capacity to monitor kits.

Further to the north, in Canmore, British Columbia, researcher Tony Clevenger is gathering DNA samples by way of hair snares to study Canada’s wolverine population. Canada’s wolverine population is more robust than the population in the US Rockies, but Clevenger and his colleagues are trying to estimate population numbers and determine whether the animals are being affected by infrastructure development.

All around, it’s been a great week in the gulo world. Now I’m looking forward to hearing about the kit expedition, and having final confirmation that F3 and M57 have babies.  (By the way, do people really celebrate the birth of a human baby with champagne? Or is it cigars? Or something else? I can’t remember. In any case, I am proposing that the birth of wolverine kits be celebrated with champagne henceforth….)

Wolverine in Oregon

Wolverine researcher Audrey Magoun, well known for her work on Alaskan gulos, picked up tracks of a wolverine last week while working on a survey project in the Wallowa Mountains of eastern Oregon. The Wallowa Mountains are close enough to breeding wolverine populations in Idaho that wolverine presence isn’t surprising, but this discovery represents the first confirmed sighting in the region.

The Wallowa Mountains (red marker) aren't far from the Payette National Forest, which has a breeding population of wolverines.

The size of the prints indicated that the wolverine is a male, which means that he could simply be a disperser. But the region might also represent another node of breeding wolverines in the archipelago of habitat islands in the northwestern US. Hopefully we’ll learn more about this as the research goes forward; Magoun and her partners plan to return next winter to determine whether the area is occupied.

The Wisconsin Department of Natural Resources has issued a general call for information on sightings of rare animals – the wolverine is included in the list, along with lynx, wolves, marten, and moose. We don’t believe that wolverines have been present in Wisconsin at any time in recent history, but it seems like the whole country wants to know more about the species, which is great.

In Michigan, the lone female wolverine who captivated the state for six years before her death last winter is now on display, for Michigan residents who want to see their state’s namesake.

It’s exciting to have such farflung news of wolverines, and especially to have news of a possible newly-discovered resident population.  Now if only we can determine, closer to home, the status of F3 and her potential kits, we may be able to add another breeding node to the map.


In an earlier post, I mentioned that March is the Month of Truth for all those researchers eagerly awaiting confirmation that their wolverines have become parents. In a post that preceded that one, I also mentioned that there are a million things that can prevent you from being able to figure this out. Make that a million and one. The easiest way to determine whether an instrumented female has kits is to fly three days in a row to see if she’s localized. Wolverines, notorious for their constant restlessness, don’t generally stay in one place unless they have something to keep them there, and that usually means either a gigantic carcass, or kits. So if the female is located three days in a row in the same place, she’s probably in a den.

The procedure is pretty straightforward, unless you live in the Rockies in a year when winter descended with fury in November and seems disinclined to leave, at all, ever. For all of March, and for the first two weeks of April, we’ve waited to a clear window to fly for three days. Patience may be a virtue, but in this case it hasn’t been rewarded. We’re still waiting.

If F3 does have kits, they are now two months old. Their fur is darker and longer and coarser, they are bigger and more active, their feet are beginning to take on the profile of gigantic snowshoes. Their tails are developing from fuzzballs into shaggy brooms, and they are undoubtedly becoming more restless to be outside. F3 may have moved them to a maternal den further upslope, a place where the snow is deeper and more secure than the natal den where they were born. The kits have about one month left in the den, and then they and F3 will head into their first summer roaming Montana’s high peaks; she and M57 will help them figure out how to find food, how to avoid predators, and how to make a living in a harsh environment. They will stay in their parents’ territories for about a year before striking out to find their own stretch of wilderness.

Hopefully we can determine at some point over the next week whether she is actually denning. Whether she is or not, female wolverines and their kits in the Montana, Idaho, and Wyoming Rockies, in the Cascades,  and, indeed, all over the world, are preparing to leave the den and head out into the wider world within the next few weeks – exciting and perilous times for the next generation of gulos.