A Territory of One’s Own

I made my way into the wolverine world by following a young female wolverine from the Absaroka-Beartooth project. Her ID was F3, and she enchanted me for years by being exactly the kind of animal I wanted to be: solitary and self-sufficient, commanding vast swaths of mountainous terrain, and – forgive the anthropomorphism – apparently unconcerned about whether she had a mate or ever produced offspring. She patrolled a huge territory in the Absaroka range, drove us crazy by raiding our traps without triggering them, and inspired a couple of expeditions into heartbreakingly spectacular country, where we were occasionally fortunate enough to find the scant scraps of an elk or a mountain goat that she had devoured. Every February, we watched her signals to see if she denned, and for years she didn’t. She just went right on patrolling her mountains, living her life in the high wild country on the borders of Yellowstone.

As a scientist, you’re not supposed to get attached to or project human qualities onto animals that you’re researching. But I was just a lowly volunteer on that project, not a scientist, and I figured I could give myself license to be inspired and awed. I had a lot of bad days back in those years, the legacy of working with torture and genocide survivors as a student and young professional. Thinking about F3 out there in the mountains prevented those bad days from being a whole lot worse. She was 18 pounds of trickster and pure momentum. She said to me, “You too can be on the landscape like this, and it will help you, too, survive.” I loved her. I owed her a debt. She gave me a template for how to find my way back into the world in front of me.

The remains of a mountain goat F3 had consumed. We retrieved the jawbone from a ledge on a cliff, almost exactly on top of a set of points where F3 had spent several days over the course of late winter and early spring, 2008

Eventually a male arrived in F3’s territory. He was captured accidentally in a bobcat trap in Menan, Idaho, and released by the Wildlife Conservation Society into the Centennial Range on the Montana-Idaho border. His ID was M57, and he promptly traveled directly to the Absarokas, where we watched his locations track F3’s through the summer breeding season and into the fall and winter.  F3 did eventually den, and gave birth to at least one male kit in early 2011. Shortly thereafter, the project ran out of funding to track them. Saying farewell to her was hard, but in a cowardly way I was glad to do it while she was still alive. In the interest of science, it would have been better to continue monitoring her, but it would have been a harder, harsher farewell to know, as we inevitably would if we kept watching her, that she was dead. I was far too attached to this wolverine, I’d imbued her with a significance and an identity that were purely constructs in my own mind, but those constructs propelled me in very real ways into very real opportunities.

Ultimately, it was because of F3 that I received an email in summer of 2017 seeking my expert review of a forthcoming children’s book on wolverines. I’m always happy to review wolverine publications, so I accepted. When I opened the file, I was first baffled, and then angered by a text that presented a deeply inaccurate picture of wolverine life history. The misrepresentation revolved around claims that male wolverines were territorial while females were not, and stated that wolverine social life involved – in language somewhat more appropriate for young children – strict control of sexual access to females by aggressive males. Females were portrayed as having undefended “home ranges” while males were territorial with the aim of mating with as many females as possible. In fact, the only reason for territoriality in wolverines, the text suggested, was male sexual control. The entire narrative centered the story of male wolverines, mentioning females only in terms of reproduction. Males dispersed. Males scent marked and defended territories. Males hunted. Males chased other male wolverines away and aggressively attacked predators without provocation, like some fantastical projection of berserker warriors. Females were there for males to mate with and to produce offspring for these males.

It was my encounter with this book draft that prompted an earlier lit review post about territoriality in female wolverines, because the author seemed genuinely surprised when I pointed out how wrong they’d gotten the story. They said they all available sources backed up their account. At first I was floored by this claim. Female wolverines are obviously territorial; this is demonstrated by study after study. I couldn’t understand how anyone who had looked at the science could possibly maintain the idea that male wolverines were territorial but females weren’t. It’s screamingly evident in the literature that female habitat requirements largely determine wolverine distribution, and that the availability of sufficient habitat for female territories will be the determining factor for wolverine persistence in any given landscape. The contention that males alone were territorial was therefore not only inaccurate, but also shifted the focus away from important aspects of the conservation debate, which revolves around female denning habitat and connectivity for dispersal by both sexes.

And yet I shouldn’t have been surprised by this writer’s insistence that there were a lot of sources out there to reinforce the inaccurate picture of female territoriality. There are. I’ve encountered them repeatedly over the years. The author was working primarily from popular press pieces, and there’s a substantial disconnect between the scientific literature and the popular literature – even the popular literature that paints itself as scientifically grounded – when it comes to the behavior and requirements of male and female wolverines.

Take, for example, National Geographic’s website entries on wolverines. They have one site for adults, and one for kids. In both, male wolverines are centered and the claim that male wolverines are territorial while females are not is perpetuated. Here is what they say about wolverines on their page for adults:

Males scent-mark their territories, but they share them with several females and are believed to be polygamous. Females den in the snow or under similar cover to give birth to two or three young each late winter or early spring. Kits sometimes live with their mother until they reach their own reproductive age—about two years old.

Here’s what they say on their page for kids:

Males mark their territories with their scent, but they allow several female wolverines to live there.

It’s interesting to note not only the basic inaccuracy of these statements, but also the way the language grants agency and personality to the male wolverine, while keeping the female in a secondary role as an object rather than a subject.

A little grammar lesson for those who need a reminder – subjects do things, objects have things done to them.

In National Geographic’s story, a male “shares” his territory, or “allows” several females to live there. The preferences of the male are assumed – and conveyed – to be the key consideration. The male is a character. He does things. He makes decisions. He shares resources. The female has his babies and then takes care of them (nowhere, of course, does National Geographic mention that males share kit-rearing duties for the year or two that juvenile kits remain in the parental territories). In fact, linguistically the female isn’t even granted this much of a role as a subject; she never does anything except dig a den and give birth. The kits (the subjects) remain with her (the object) for up to two years, then they leave. She never does anything beyond her instinctual reproductive act.

This narrative of male activity, agency, and territoriality was recently reiterated in another popular piece on wolverines, this time in the Yukon news:

Males have large territories which overlap those of two to three females, all of which he mates with. This sort of sexual courtship and selection by proximity is not uncommon — the tough-yet-cuddly pika employs a similar strategy — but what makes the male wolverine unusual is that his interest does not end after mating season. Instead, males will continue visiting their mates and the resulting litters in a kind of paternal timeshare arrangement, investing considerable energy in their offspring, which are called kits, Jung says.

“They’re actually very social, with good family tendencies,” he says. “They spend time just teaching young wolverines how to be wolverines…. It’s a bit unexpected.”

Males have well established ranges, and, due to their low population density, rarely encounter each other, making male-on-male aggression relatively low for such a powerful and territorial animal.

“They have their territories and other males respect that,” says Jung.

Great, but what are the females up to? Where do their preferences come in? How do they control their territories, and why are they controlling territories in the first place? This piece does implicitly acknowledge female territoriality and also male parental investment (a characteristic often associated with some degree of female sexual selection for prosocial behavior), but still assumes that the male is the active agent in the story.

Even in pieces for the popular press and social media by competent wolverine researchers, even in pieces where the territoriality of females is acknowledged, this kind of male-centered language persists. I’m not going to pick on individual researchers here, but well before the children’s book debacle, I had to put in place a policy on not publicizing any piece of writing or media that used sexist language – in particular, pieces describing “a male and his females.” This kind of language came across my desk, from within the research community, often enough that it required an internal rule for what I would share on my blog and on social media. The decision was about accuracy – a description of “a male and his females” is an anthropomorphic device that belongs to the era of heated Victorian Orientalist fantasies of the harem, not to science writing. But it was also about insuring that no subliminal messages were conveyed to men who might experience the sad tendency to use their anthropomorphic perceptions of the social order of wildlife to excuse behavior in their own labs or extended communities. The issue of men harassing women is as real in the scientific community as it is elsewhere, and who knew what sort of subconscious permission such descriptions might convey?

Those deluded men aside, I don’t want to suggest that all of these examples are necessarily the result of conscious sexism on the part of the writers of this material. In fact, some of the authors I’ve referred to are women. But it’s precisely the fact that this language is probably not conscious that I want to consider in more detail.

Here’s another paragraph:

Female wolverines disperse and establish territories at around two years of age. A female may travel widely before she finds a suitable location, but once she does, she defends and scent-marks her territory against other females. She may permit a male to remain, and she may share him with other females who tolerate his presence in their territories. She mates with her male in the summer, but holds the fertilized eggs in suspension until the winter. If she is in good condition, she will become pregnant sometime in December, and give birth to her young in early February. Her male will visit her den and may bring her food. Once the kits are weaned, they may travel with either parent for a year or two before dispersing to establish their own territories. Male wolverines may indicate their suitability as a mate to females by diligently participating in kit-rearing activities, allowing a female to select for reproduction that is less costly to her and therefore in her own best interests.

I wrote it, of course. This paragraph is no less accurate than anything that’s been written about wolverines in the popular literature, and yet in rearranging the subject and object, in centering the female and her actions, I’m guessing that it probably strikes some readers as wrong or off. To suggest that female wolverines are sharing a male or possessing a male is a linguistic device, but it’s neither more nor less true than suggesting that a male wolverine controls and mates with “his” females and then supervises their production of his kits. Why then do we often see references in popular wildlife writing to “a male and his females,” and never (to my knowledge, although I will send a wolverine sticker to anyone who can give me an example of this in a piece on mammals) to females sharing a male, or to a female and “her” male?

Most scientists are assiduous about avoiding anthropomorphic language when it attributes motivations, emotions, or human-like thoughts or behaviors to animals. And yet linguistically, when we discuss wildlife biology, we reproduce human (and largely Western patriarchal monotheist) gender roles despite ourselves. This is something that is so deeply embedded in our language and our culture that it would take real and constant work to avoid it. Most scientists and science writers think that they are capable of objectivity without that level of attention to language. I’d like to suggest that they aren’t capable, which explains why even otherwise decent, conscientious people casually use the language of male territorial dominance and sexual aggression without any evidence that this is the actual dynamic at play in animal lives.

Or in short: perhaps popular science writing about wolverines neglects female territoriality because it’s culturally antithetical, and therefore linguistically awkward, to talk about females possessing, controlling, hunting, attacking, selecting, creating, deciding, dominating.

When I initially started working on this post this past summer, I went to the public library and checked out, at random, 14 children’s books on wildlife. I wanted to see how pervasive such gendered wildlife storytelling was in books for young children. I had two main concerns at that point. One was the way in which subconscious gender bias limits the questions that scientists may ask – and indeed, the things that scientists may be capable of observing –  when it comes to wildlife (more on that, and its potential repercussions for conservation, below). The other concern was how this sort of language depicts ostensibly objective, “scientific” and “natural” sex roles to children who are too young to have any awareness of the cultural constructedness of gender. The effects of exposure to such purported truths about the natural behaviors of male and female animals might, I thought, be negative for both boys and girls, cis-gender and trans alike.

I worked on the post fitfully over the next few weeks, delving into literature about different attitudes towards wildlife among women and men, girls and boys, and digging up two old anthropology articles that, back in college, had first raised my interest in the ways that academic experts express unintentional bias through language choice (in this case, the two articles were about marriage customs, one dealing with polygynous marriages in Africa, in which “men have multiple wives,” another dealing with polyandry in the Garwhal Himalaya, in which “men share a wife.” Where, I wondered, reading these articles at age 19, are the women sharing a husband, the women having multiple husbands?) My intent was to show how this morass of literature, from children’s books to academic articles, conveyed both information about the wider world to various types of student, and also, through choices about how to describe that information, purveyed and reinforced particular cultural assumptions about sex, gender, relationships, and power. I had plans to talk in that original post about the newfound veneration of the “natural” among the current child-rearing generation, and how that veneration has led to things as various as the rise of organic food, the dangerous anti-vaccination movement, the silly “paleo” diet, stressful dynamics around natural childbirth and breastfeeding, and other claims about living a better life through an imagined pre-industrial, pre-agricultural authenticity. In light of this, any story that told young children that being male involved a “natural” tendency to control the sexuality and reproduction of females, and that being female involved being a passive object to be fought over and possessed without any active choice in the matter, seemed doubly perilous.

This was a pet project at the time. It was personally relevant because I had been sensitive to these kinds of narratives about sex and gender as a child. I knew by age five that following the life course that was socially gendered as female – namely, taking a male mate and producing a family –  was not in my future, and throughout my childhood I wanted, more than anything else, to find a model for being an autonomous, self-directed, independent female person active in the public world. Stories and animals were both important guideposts in that process. So the topic of human gender roles in animal stories was highly personal. But I didn’t think that there would be much broader relevance to a piece about how depictions in children’s books of male sexual aggression and territoriality among wild mammals might reflect something about the way men and women behave in America. Given the sexual predator occupying the White House, it hardly seemed like there would be a receptive audience for subtle and elaborate arguments about how we use wildlife stories to indoctrinate our children to believe that it’s natural for a female to accept, without question, the sexual advances of whatever bombastic male shows up in her vicinity, let alone the even more subtle and elaborate argument that overlooking the territoriality of female animals conveys a message to young children that establishing territories (or, analogously, having ambitions, staking a claim to a field, defending their own visions, setting out into the world and adventuring and making a life for themselves on their own) is not something that females “naturally” do.

Then the Harvey Weinstein story broke.

Like many other women who have suffered harassment and bullying in professional situations (and that’s all of us, isn’t it?), I found myself mesmerized and nearly paralyzed by the pageant of courage and slime that simultaneously poured forth as the #metoo movement gained momentum. Part of the paralysis was the way the stories pushed many women back into the dark spaces of past private horrors – if you were fortunate enough to have escaped having been the target of physical violence yourself, chances were that you were supporting friends who hadn’t been so lucky, while also trying to fit your own less violent but still disturbing experiences into this bigger and suddenly very visible narrative. We were forced to relive and mourn the opportunities lost when our high school grades imploded after we walked out of the classroom of a high school teacher who harassed us, or the way our work suffered when we suddenly had to manage a sketchy boss whose inappropriate interest required the expenditure of extra energy and effort to remain professional, or the stress and collapse of motivation that followed having to deal with a narcissistic, bullying man claiming credit for our work and screaming abuse at us when we challenged him. Just to pull a few random examples out of, say, my own past.

Beyond that, there were so few news stories examining the causes of harassment or inappropriate advances, so few stories calling for men to be self-reflective about their role in these situations. The message was, “Women, step up! Put yourself through the mental and emotional agony of making these accusations because right at this moment, we’re willing to listen to you!” The message was not, “Hey, men who are in a position of power relative to the women in your professional lives, think carefully about whether you REALLY need to proposition a woman whose career is entangled with yours – do you think that might possibly put her in an awkward situation? Yes? Well then sit down and keep your mouth shut and your pants zipped.” Predatory men were scared and squirming, no doubt. But not one of the men taken down in this series of scandals has had the courage to step up and say, preemptively, “I know I’ve done wrong, I’ve treated people this way in the past and I regret it, I apologize, and I resign.” Not that victims stepping up is a bad thing, but the ultimate message was that misbehaving men, on the whole, are incapable of holding themselves to any standard of behavior, because this sort of aggression is “natural,” and that survivors (male or female) must, on top of everything else, undertake the task of making them accountable. And even when held accountable, the perpetrators appear incapable of any actual growth as human beings; the apologies offered so far have been, without exception, lacking in self-reflection or true remorse.

To me, though, the most depressing thing was thinking about all of the art that never got made, the science that never got done, the brilliant business ideas never enacted, the potential never realized, the many women who struggled to support their families on less than they should have, because these barriers were put up, time and again, to equal participation in the workforce and public life. Sex is a subsidiary part of this exclusionary process, a locus of denigration in relationships where power is contested, but there is a much bigger issue at play than parsing the definitions of which body parts in which proximity with which degree of consent constitute “inappropriate sexual behavior.” What we are looking at now is a deep cultural reckoning, and most of the babble in the media is about the wrong topic. The predictable accusations of puritanism and sex-panic, of the overreach of the sexual revolution, of the lack of character of women who just needed to stand up for themselves and not be victims, were hurled from sources near and far, highlighting America’s eternal, tiresome, prurient obsession with the psychic danger of sex, the risk of pollution (in the anthropological sense) that sex poses to public institutions and public figures and the workplace itself. But very few people or media outlets have talked about the real underlying gender issue, which is our country’s equally tiresome discomfort with female participation, ambition, and vision. This is a nation that cannot decide whether it wants women in heretofore exclusively male public territories like the arts, politics, and business. Masturbating into a potted plant in front of a woman who is hoping to make it in the entertainment industry is not about sex; it’s about reinforcing to the woman that she is in a male territory and that the perpetrator of said potted-plant-masturbation wants it to remain male territory.

In short, the question is not, “What, exactly, constitutes sexual assault?” The question is, “What behavior interferes with an individual’s ability to work to her potential?” Whether that potential involves raising a family or rising to genius in the arts or sciences, having to deal with a man making insinuating comments, groping and assaulting you, or simply being verbally abusive or belittling in a nonsexual way, is an obstacle to thinking of a professional territory as your own.

Back into this mess loped the F3 of my imagination, and she showed up with questions: When, if ever, do we contemplate what a solitary female animal does with her time and her energy when they are her own, unimpeded, directed exclusively by her own will? What does she do with her talents when there’s no one to push her around or get in her way? How does she establish and demarcate her territory, and how do we discuss what she’s creating and defending? What is the “natural” state and behavior of the independent female animal?

As it turns out, of those 14 children’s books, only one contained the kind of biased language I was worried about. It was about deer, and it did indeed refer to “a male and his females,” but it was also a very old book. Newer books were far more gender neutral. There was an excellent series of books on wildlife research featuring both male and female scientists and great storytelling about their work and their species of interest. Things were not as dire as I’d assumed they would be (although my 14-book survey was hardly exhaustive, either).

Is this progress?

I don’t know. I do know that animals have served as analogies and symbols for humans for as long as we’ve recorded our visions of the world. When we celebrate or even highlight qualities or characteristics of a species, we usually find something resonant for ourselves in those qualities. Even scientists tend to slip through the veil of ostensible objectivity when they talk or write in lay terms about their species. I certainly do it, and I’ve hung out with other scientists for long enough to have seen and heard them do it too. We speak with authority, and that makes these slips interesting, because they convey values and worldview under the guise of authoritative objective fact. It’s something to think about, something to be aware of, and something to combat, especially when it affects the lives – and the work – of half of the world’s human population.

It’s also something to think about and combat because it’s scientifically problematic. This is a topic that deserves a post of its own, but in short, if you’re looking primarily at male animals and their needs, if you’re seeing them as the center of the story, you may be blind to important dynamics that are scientifically intriguing and also have implications for management. We see what we are trained and habituated to see, and that constrains our ability to observe and to imagine. It also constrains our ability to implement effective conservation measures. If, for example, some degree of female sexual selection is operating in the case of wolverines – if a female wolverine is picky about her partner, if she chases off males she doesn’t like, if she simply refuses to mate with or bear or raise the kits of a male she dislikes (infanticide happens…), if, in a worst case scenario, a female wolverine leaves her territory and sets up a new one when she dislikes a resident male  – then it would have implications for everything from trapping (removing any adult animal is likely to be catastrophic to reproductive success of a given population node) to reintroductions (randomly paired animals are less likely to successfully establish a reproductive population) to connectivity (the landscape must be fully connected not only to insure successful dispersal but also in order to allow a suitable supply of males for the female to select one who meets her preferences). A scientist wedded to the idea of male sexual dominance and male sexual selection through competition and territoriality would be functionally intellectually impotent in the face of such dynamics.

I mention this only as a “what if,” not to make a statement that female sexual selection is at play among wolverines. But I will add a final note on F3, my female wolverine from the Absarokas: her kit was not fathered by M57, the male who followed her for months and who regularly visited her den while she was nursing the kit. The kit’s DNA excluded M57 from its lineage, which means either that F3 was sharing her territory with two males, or that she mated with a disperser who was passing through. M57 was observed in close proximity to the den site, both via telemetry and in person by the crew that skied in to locate the den site. Maybe he knew F3 had chosen another male and was trying to kill the kit or kits (the crew retrieved DNA from only a single kit), or maybe he was helping to raise it because the social bond he shared with F3 – winning her favor and approval by demonstrating his parenting skills and his acquiescence to her needs – was ultimately more important to his long-term evolutionary success than passing on his genes in a single year.

Maybe in her territory, her rules govern. It’s a hypothesis to explore in wolverine research, and – perhaps more importantly – it’s a rule to live by in the human world.

F3’s den site in late summer 2011. The chambers were beneath the downed trees. Note human for scale, and pink tape in tree overhead. The tape marks the approximate depth of the snow in May, when the crew skied in and observed M57’s tracks (verified by collar location) in the area.

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

Of necessity, this piece focuses mostly on the male-female dynamics of workplace harassment, since that relates most closely to the gender-essentialist narratives conveyed in wildlife writing. But any time power is used to humiliate or drive out any innocent individual and thereby limit their potential, it’s wrong, whether that individual is female or male. This piece also deals largely with cis-gender heteronormative definitions of sex and gender, male and female. This too is something that I consider problematic in the way that wildlife writing conveys a “biology is destiny” story, even when we know that this isn’t true for some animals (you all will enjoy reading about the wide variety of same-sex mating and partnering in the animal kingdom here, and about various birds in same-sex partnerships here, here, and here). I cannot address these dynamics fully without making this piece unreadably long, but I am 100% supportive of complicating the gender narrative as much as possible and am also 100% supportive of all trans and LGBTQIA folks as we broaden the possibilities of lives lived to full potential. 


Territoriality in Female Wolverines

For reasons that I’ll get into in a future post, I feel suddenly compelled to write up a quick literature review on the topic of territoriality in female wolverines.

Let’s get this out of the way immediately: female wolverines are territorial. This is evident throughout the recent literature. Out of concern for the safety of resident adult wolverines in the US, researchers generally don’t publish maps of wolverine home ranges, but anyone who has had the chance to look at the minimum convex polygons of study animals can see a pretty clear pattern. Adult female wolverines don’t overlap with other adult female wolverines. The territorial boundaries are pretty strict, often down a drainage that both animals will approach and traverse, but that neither will cross. There are instances of incursions and small amounts of overlap, but this is generally less than 2% of any female’s home range. Adult males are also territorial, but with varying degrees of territorial incursion or excursion. The territoriality of wolverines is one of the most important factors for understanding wolverine distribution, their natural rarity, and, importantly, conservation concerns and strategies as we look at a warming world.

Strictly speaking, a territory is a patch of ground that an animal defends, and a home range is a patch of ground that an animal occupies and uses for subsistence. In the wolverine research community, including in published papers, these terms are used in a conflating fashion, although some papers do make a distinction. In presentations and talks and casual conversation, we often use the words “home range” to refer to the area that a wolverine (male or female) occupies, but we mean this as a defended home range, which is actually a territory.

Territoriality in the Literature

While the territoriality of wolverines is widely understood at this point, I was surprised to note that there are few American or Canadian papers or book chapters that deal explicitly with the question of how territoriality functions, or the ways in which it potentially limits population in areas of restricted habitat where the population fragments into a meta-population structure. The Scandinavians, on the other hand, do tend to deal with territoriality, probably because the management imperatives are more urgent in places where depredation on domestic reindeer is a major problem. A Norwegian master’s thesis from 2014 looks at genetic sampling as a method to determine territoriality, in comparison to GPS collar data. Jens Persson’s dissertation deals in some depth with possible explanations for territoriality, and how those explanations may differ between males and females. Proving that the Scandinavians more or less own this topic, a 2017 thesis by Malin Aronsson closely focuses on the dynamics of territoriality and dispersal among female wolverines (and lynx). But the territoriality of the species is taken for granted in most publications, especially the North American publications.

I was also reminded of the absence of peer-reviewed publications focusing specifically on several of the major American wolverine research projects. Doug Chadwick’s popular-science book The Wolverine Way remains the best published account of the Glacier wolverine project. The Rocky Mountain Research Station has put out a number of impressive papers that draw on the Glacier data to ask large-scale questions about habitat relationships, population genetics, dispersal, and climate change effects, but the annual project reports remain the best source of information for the park population itself. The same is true of the Absaroka-Beartooth project, the project with which I got my start in the wolverine world, working as a volunteer. Peer-reviewed papers for that project were somewhat limited by the low numbers of detected wolverines within the study area – sample sizes and statistics being the perennial priority for most journals these days – but the eerie emptiness of prime modeled wolverine habitat deserves some consideration, hopefully in future publications.

Back in 1981, Hornocker et al published a study asserting that wolverines were not territorial. This was one of the earliest studies of wolverines in the lower 48, lasting from 1972-1977, on the Flathead National Forest. It was a telemetry study in which the researchers observed overlap among many different wolverines, and concluded that wolverines were tolerant of fellow wolverines. They reported “no intraspecific strife” and discussed how a wounded female wolverine, whose injuries they first attributed to another wolverine, were likely caused by a mountain lion. (Despite assertions that wolverines are not territorial, the home range maps that are included in this paper do show a familiar pattern – two male wolverines who don’t overlap, one female wolverine who sticks to a fairly tight home range, and a second female, overlapping the first, who makes wider movements that include the home range of the male who overlaps the first female. If I were to guess, many years later, what was up with this scenario, I’d suggest a male-female pair and their juvenile daughter, preparing to disperse. The second male looks like an unrelated individual as his range does not overlap with any of the other animals.) Earlier observational studies of wolverines, and books about the species, also fail to make note of territorial behavior. The same is largely true for the Mongolian hunters and herders who I interviewed; they were well aware of the wolverine’s rarity and ability to travel over long distances, but only a few noted that a wolverine would reappear in a particular spot at intervals. None of those interviewees made a leap to territoriality as an explanation, but some did refer (maybe jokingly) to a wolverine’s nutag, which is a Mongolian concept denoting an individual’s homeland.

Home range maps showing seasonal movements for four wolverines in NW Montana, from Hornocker et al 1981

Home range maps for four wolverines in NW Montana, showing seasonal movements, from Hornocker et al 1981

Observation, track surveys, and radio telemetry, of course, are limited in important ways. These methods allow glimpses of an animal only at the moments when the observer or listener happens to have their eyes or telemetry antenna trained on the animal. Finding dens is more difficult, which – in the absence of DNA techniques – makes understanding relatedness more difficult as well. With the advent of GPS collars and DNA analysis, we were able to observe wolverines more closely and consistently. Hundreds of locations for multiple animals, taken over months, in combination with VHF locations over the course of years, made the territorial behavior of the species clear. Den locations and kit collaring showed that wolverines will tolerate their own offspring within their territories for up to two years after birth. This could account for Hornocker’s and others’ observations of multiple wolverines sharing the same home range, and photos like those that Igor Shpilenok took in Kamchatka, of up to six wolverines on a bear carcass at the same time.

The Wildlife Conservation Society’s Yellowstone Wolverine Project likewise relied on annual reports and white papers to convey results for many years. The project director, Bob Inman, was in the process of getting his PhD, so his dissertation eventually yielded several published papers. Again, though, these deal mostly with larger-scale questions about habitat relationships and conservation priorities. Several of his papers do discuss territoriality, but again, for obvious reasons, most of the published papers don’t include home range maps.

What all of these papers and sources do include, however, is an assumption that territoriality is important. Some imply territoriality; for example, in a summary of draft papers from 2007, the WCS project notes in the abstract for a chapter on wolverine space use:

Mean annual (1 Mar–28 Feb) 95% fixed kernel home range size was 453 km2 for adult females (n = 15 wolverine years) and 1,160 km2 for adult males (n = 13 wolverine-years). Mean percent area overlap of same-sex adults was < 1% (SE = 0.00, range = 0–2%, n = 12 pairs) using annual 100% minimum convex polygon home ranges.

The “<1% overlap” suggests territoriality, although it’s not explicitly stated here. In a 2012 review of wolverine reproductive chronology, however, Inman et al do note this:

Throughout its distribution, the wolverine displays extremely large home ranges, territoriality, low densities, and low reproductive rates (Copeland 1996; Inman et al. 2012; Krebs et al. 2007; Lofroth and Krebs 2007; Magoun 1985; Mattisson et al. 2011a; Persson et al. 2006, 2010). These adaptations are necessary for exploiting a cold, low-productivity niche where growing seasons are brief and food resources are limited (Inman et al. 2012).”  

Another 2012 Inman et al paper on spatial ecology does deal explicitly with the question of territoriality vs. undefended home ranges and is probably the most extensive discussion of this topic in the literature on wolverines in the lower 48. This paper does include some home range maps, with the locations stripped out.

Spatial distribution patterns of the Mustelidae are typically described as intra-sexual territoriality, where only home ranges of opposite sexes overlap (Powell 1979). Wolverine-specific reports exist for both intra-sexual territoriality (Magoun 1985, Copeland 1996, Hedmark et al. 2007, Persson et al. 2010) and for a high degree of spatial overlap but with temporal separation (Hornocker et al. 1983). Arguments against territoriality by wolverines include the lack of ability to defend such a large home range (Koehler et al. 1980). Our data on movement rates in relation to home range size, temporal development of the home range, minimal overlap of same-sex adults, and relatively immediate shifts upon a death suggest that wolverines are capable of patrolling a large territory and provide further support for intra-sexual territoriality. Reproductive success is closely correlated to the amount of energy that a female wolverine can obtain (Persson 2005), and for predators that are capable of individually acquiring prey, the presence of conspecifics reduces foraging efficiency (Sandell 1989). Since wolverines feed on individually obtainable prey and occupy relatively unproductive habitats, it follows that behaviors for maintaining exclusive access to resources would likely have selective advantage. Frequent marking behavior (Pulliainen and Ovaskainen 1975, Koehler et al. 1980) is likely part of an adaptive strategy that involves maintenance of exclusive territories within sexes so that feeding and breeding opportunities are monopolized by dominant individuals and their immediate offspring.

Female wolverine territories in Wyoming, with takeover of one home range by a female kit after the death of the resident adult female. From Inman et al 2012

The Scandinavian literature is also rife with references to territoriality among both male and female wolverines. Jens Persson, who works on wolverines in Sweden, reflects in his dissertation on the reasons for territorial behavior in female wolverines, and concludes that it’s related both to food, and also potentially to the need to protect kits against infanticide. Historically, it was widely believed that male wolverines would kill any kits they encountered, even their own; this has since been proven false, but the idea that males kill unrelated kits persists. Persson is the first researcher I’m aware of to suggest that female territoriality may actually be a defense against other females intent on infanticide.

Females could also gain from infanticide by eliminating non-related progeny to decrease future competition for territories or denning areas for her and her progeny. In addition, the death of an unrelated infant could also reduce the net reproductive success of a competitor (Hrdy & Hausfater, 1984). Competition for territories determine dispersal behaviour in female wolverines (Paper IV), suggesting that there is strong competition for territories among female wolverines.

 Wolff and Peterson (1998) hypothesized that a primary function of female territoriality in solitary mammals could be to protect vulnerable young from infanticidal conspecific females. Four predictions can be deduced from their offspring-defence hypothesis: 1) Female territoriality should be associated with young that are vulnerable to infanticide. 2) Female territoriality should be associated with defence of offspring, and therefore most pronounced during the offspring-rearing season. 3) Defence will be greatest against the segment of thepopulation that commits infanticide and against those individuals that females can dominate. 4) Optimal territory size should be a function of intruder pressure, intruder detectability, female response distances and offspring vulnerability, and changes in food abundance and distribution should not affect territory size directly unless they are correlated with the other factors. In concordance with predictions 1-3, wolverines have altricial young that are vulnerable from late winter until late summer (March – August) and female territoriality seem to be strongest during this period (Magoun, 1985; Landa, Lindén & Kojola, 2000). We lack data to evaluate prediction 4. However, in contrast to prediction 4, I believe that food actually is an important determinant of territory size in wolverine females (see Banci, 1994).

Malin Aronsson’s 2017 thesis examines the territorial dynamics of female wolverines, using the vast dataset from Swedish studies dating back to the 1990s. She makes some interesting observations about the counter-intuitive conclusion that wolverines are territorial despite living in low-resource environments, which is the opposite of what studies on other carnivores would suggest:

Wolverines are highly territorial (Persson et al. 2010), and by comparing space use overlap between years for the same individual I found that wolverines show high territorial fidelity resulting in a stable distribution of resident individuals. Interestingly, territorial fidelity in general is predicted to be low in habitats where food resources are low, variable, unpredictable or deplete fast (Wauters et al. 1995; Kirk et al. 2008; Edwards et al. 2009), which corresponds to the characterization of wolverine habitat in general (Inman et al. 2012b), and particularly in this study area (Person 2005). However, scavenging and caching are integral parts of wolverine biology (Inman et al. 2012b; Mattisson et al. 2016), which increase resource predictability, decrease depletion rate and create a valuable resource (i.e. cache sites) to defend, promoting high territorial fidelity despite the unpredictable environment (Tye 1986; Eide et al. 2004). In addition, occurrence of more efficient predators, such as the Eurasian lynx (Lynx lynx), provide carcasses for direct consumption and caching (Mattisson et al. 2011b). Furthermore, both males and females showed higher between-year fidelity at the territory level (i.e. 90% isopleth) compared to the core areas (i.e. 50% isopleth). That fidelity was lower at the core area compared to territory level suggests that it is critical to maintain the outer territory boundary to secure long-term resources, while the most used area within the territory may vary between years due to spatial fluctuations in key resources, or, for females, location of den sites may vary between years.

Aronsson also documents a few cases of territorial adult females shifting territories after successfully reproducing. Why this happened, and how frequently such moves occur, would be interesting questions for further investigation.

Another Scandinavian paper, a master’s thesis from 2014 by Espen Gregersen, compares home range and territoriality derived from GPS data to those derived from scat analysis. The question in this thesis was not so much “are wolverines territorial?” as “can wolverine territoriality be detected using non-invasive methods like scat analysis?” It’s an interesting question and one of relevance to those of us who have limited resources for large-scale trapping efforts in places like, say, Mongolia. Gregersen concludes that yes, we can indeed determine home range size and observe territoriality using scat samples – but it takes a very large number of samples. This thesis also addressed the question of territorial turnover after the death of a resident adult, which is particularly interesting at the southern edge of distribution, where wide separation of habitat patches makes recolonization less certain.

Finally, a forthcoming book chapter from Copeland et al. proposes a slightly different take on territoriality among male and female wolverines. That chapter will be out soon and I’ll look at it in depth once it’s published, but it too reinforces the idea that female wolverines are highly territorial, and maybe even more strictly territorial than males.

There are many other papers out there that include brief mentions of territoriality and intrasexual exclusion in home ranges. These are just a sample, and this write-up fairly cursory, but I hope they’re adequate to illustrate that wolverines – both male and female – are territorial.

Territoriality and Conservation

At this point, territoriality in wolverines is accepted as an important feature of their life history and ecology. The question of why hasn’t yet been answered, but the fact that wolverines require such large territories, and the fact that their reproductive rates are so low, accounts for their natural scarcity on any landscape – let alone one in which suitable habitat is located only at certain elevations in widely scattered patches across a sea of non-habitat.

Female territories structure the wolverine population. Females must have adequate resources to meet their needs and, hopefully, to reproduce. They occupy and defend territories that allow them to do this. Males in turn seem to select for territories that overlap with resident females. Whether this represents a territorial strategy for sexual monopoly, or whether it’s defined by the male’s capacity for paternal investment, or some combination, is worth investigation (male wolverines seem not to always entirely encompass a female’s territory, leaving her open to potentially overlap with other males, which raises questions about the accepted narrative of males “controlling” access to females). Both males and females disperse over long distances, although the longest movements have been observed in males like M56.

Habitat availability for females is the limiting factor on wolverine population growth and range expansion in the US Rockies. I’d hypothesize that keeping a certain number of territories occupied is critical to the long-term persistence of wolverines in the lower 48, and that there is some distinction to be made between female population numbers, strictly speaking; the percentage of habitat that’s occupied; and where that habitat is located in relation to other habitat. There’s been an enormous focus on “connectivity”– concurrent with the fashion for corridors among conservationists –  but a surprising lack of attention paid to the population nodes themselves. For example, the question that Gregersen raises about recolonization of vacant territories is interesting and important, especially given the observed disappearance of wolverines from places like the Tetons. Presumably this disappearance represents some kind of natural cycle of die-off for a relatively isolated population node, but how long does it take before those territories are reoccupied? And how is time-to-recolonization related to population density and occupancy of the next-nearest population nodes? Questions about functional connectivity among wolverine population nodes are important, but connectivity as a single conservation strategy for wolverines seems like an odd allocation of resources; wolverines don’t migrate, they disperse, and their dispersal patterns are unique and erratic. They are likely to benefit from the broad and intense focus on connectivity and road-crossing structures for other species, but trying to preserve wolverine-specific corridors seems like a good recipe for driving oneself nuts. As one of my Mongolian interviewees once said when discussing wolverines, “One day it’s here, the next day it’s 50 kilometers away. It could turn up anywhere!” I hope to see a greater focus on what’s going on within habitat in the future, including investigation of questions about what drives territoriality and territory size, and how territorial turnover works in a meta-population.

That’s it for now. If any of you have any thoughts about the function of territoriality in female or male wolverines, if you want to point out an obvious resource on this question that I overlooked, or if you just want to say hi, please feel free to comment.

References (with apologies for lack of consistent style formatting and for referring to multiple authors as “et al” instead of writing them out. Time constraints!)

Aronsson, M. 2017. ‘O Neighbour, Where Art Thou?’ Spatial and social dynamics in wolverine and lynx from individual use to population distribution. Doctoral dissertation. Swedish University of Agricultural Sciences. Uppsala. ISBN (electronic version) 978-91-576-8822-4

Chadwick, D. 2010. The Wolverine Way. Patagonia press.

Copeland, J. P., Landa, A., Heinemeyer, K., Aubry, K. B., van Dijk, J., May, R., Persson, J., Squires, J., and Yates, R. 2017. Social ethology of the wolverine. In: Biology and Conservation of Musteloids. Edited by David W. Macdonald, Christopher Newman, and Lauren A. Harrington: Oxford University Press. DOI 10.1093/oso/9780198759805.003.0018

Gregersen, E. 2014. Assessing territoriality in wolverines (Gulo gulo) using non-invasive genetic sampling. Master’s thesis. Norwegian University of Life Sciences.

Hornocker, M and H Hash. 1981. Ecology of the wolverine in northwestern Montana. Canadian Journal of Zoology. V. 59. pp. 1286-1301.

Inman et al. 2007. Wolverine space use in greater Yellowstone. In Greater Yellowstone Wolverine Program Cumulative Report. Wildlife Conservation Society.

Inman R. et al. 2012. The wolverine’s niche: linking reproductive chronology, caching, competition, and climate. Journal of Mammalogy 93(3):634-644.

Inman, R. et al. 2012. Spatial Ecology of Wolverines at the Southern Periphery of Distribution. Journal of Wildlife Management. 76(4). 778–792. DOI: 10.1002/jwmg.289

Persson, J. 2003. Population Ecology of Scandinavian Wolverines. Doctoral dissertation. Swedish University of Agricultural Sciences. Uppsala.