Female Wolverine in the Cascades

While we’re on the topic of female wolverines, a la F3 and her adventures, here’s a post that I wrote a few weeks ago but didn’t get around to publishing. I was reminded of it as I chatted with my younger sister about her training program for the upcoming Boston Marathon on April 19th:

The 150-mile  journey of an intrepid young female wolverine in the Cascades was highlighted in an article published on Friday, adding another data point to the growing record of impressive dispersal distances among juvenile females.

Juvenile male wolverines  seem to be more itinerant over longer distances, but it appears that females are capable of long-range dispersal when necessary.  These numbers aren’t precise, but a pair of females born in the Tetons in 2004 traveled widely, one ranging from the Tetons to the Palisades to the Wyoming Range and finally back to the Tetons – a straight-line distance of at least 200 miles. Her sister traveled from the Tetons to the southern end of the Wind River Range, a straight-line distance of at least 100 miles. Another wolverine born in the Gallatins traveled across Yellowstone to the Thorofare and settled there, a straight line distance of about 100 miles. Undoubtedly all three of these wolverines took more circuitous routes and covered more country than these numbers suggest. The case of the Cascade female fits with a trend in data that suggest that female wolverines may not travel the same huge distances as males, but are still capable of impressive marathons.

We know so little at this point that much of this is speculation, but wolverines of either sex are likely compelled to keep moving until they find a territory that is unoccupied by a same-sex member of their species and that is capable of supporting their needs – in the case of males, the territory ideally should support a mate; in the case of females, it will need to provide adequate denning habitat and the resources to raise kits. Male territories tend be larger, which means that for a male wolverine, the landscape will fill up faster than it will for a female, requiring him to travel more widely, and generally in advance of females. But once a given landscape is full of mature females, a juvenile female will be equally compelled to keep traveling if she wants to make a living and potentially reproduce. Males will probably range over greater absolute distances, but females will also be long-range travelers if necessary, moving until they find a territory – whether recently vacated by a deceased female, or previously uncolonized – that suits their needs.

An interesting point about the situation outlined in the article is the fact that none of the study’s collared wolverines, male or female, seem to be staying in the Twisp River drainage or the study area, but continue to travel widely. Perhaps over the longer term this will help us refine our understanding of habitat requirements, of how and why wolverines move over the landscape in certain ways, and of how and why they select certain territories over others.

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