Climate change's threat to the wolverine

 

The word “imminent” conjures images of an onrushing tidal wave, something unstoppable and certain, an action or event on the verge of bursting into reality. The Dec. 13 decision that the wolverine was warranted but precluded for protection under the Endangered Species Act (ESA) hinged on a different definition of this word: to the US Fish and Wildlife Service, “imminent” means “ongoing,” and in the 134-page decision, the primary threat to wolverines, climate change, was deemed “of high magnitude,” but not “imminent (ongoing).” For now, Gulo gulo has been seated, along with 250 other candidate species, in the ESA’s waiting room. The decision will be revisited every year until the species is either listed, or deemed not warranted.

Wolverine F28, in Glacier National Park. Courtesy Jeff Copeland.

Two papers are at the heart of the decision; the first is retired wolverine biologist Jeff Copeland’s 2010 paper showing that wolverines depend on deep spring snow cover and cool summer temperatures, and the second an unpublished paper by the Rocky Mountain Research Station’s Kevin McKelvey, modeling the effects of climate change on Rocky Mountain wolverine habitat over the next century. The first provides evidence that wolverines depend on cold and snow; the second shows that those two commodities will diminish in coming decades, reducing wolverine habitat by 23 percent by 2035, and 63 percent by 2099. In a meta-population that depends on long-distance dispersal to maintain genetic viability, the reduction in habitat will increase distances between high-altitude population islands and reduce the number of available territories to support reproductive wolverines. This is the crux of the threat.

Other potential issues, including managed trapping, disturbance by recreation or industry, and reductions in connectivity due to development, were deemed secondary. These activities in and of themselves probably don’t pose a high magnitude threat to a healthy wolverine population, despite being potential sources of mortality for individual animals. In concert with the effects of climate change, however, and in synergy with each other, this suite of minor disturbances could become overwhelming. In a fragmented and naturally rare population at the warming southern margin of its range, every individual counts, and the loss of a single reproductive female could be devastating to a population.  Increasing regulation to protect every animal on the landscape is not an immediate prospect, but the decision clarifies that if the primary threat is not addressed, we might have no option but to regulate for secondary threats in the future.

For those of us involved with wolverine research and conservation, the decision represents a huge accomplishment despite the ambiguity of the wolverine’s new status. In 1993, when the wolverine was first petitioned for listing, data were too scarce to even make a determination about the animal’s situation. In 2008, in a decision widely perceived to be based on politics instead of science, the Bush Administration decided that wolverines in the US were too closely tied to Canada’s wolverines to be worth protecting, despite a body of science that elucidated both the distinctness of the population, and some of the threats it faced. In 2010, we finally have a decision that not only draws on reliable data about wolverines, but that demonstrates will to openly address the controversial topic of wildlife conservation in the face of climate change. The scientists who spent years obtaining hardwon wolverine data, the advocates who pushed the government to reconsider earlier decisions, and the authors of the current decision have done admirable work.

This brings me back to the word “imminent.” The USFWS’ decision is sound, because even if the wolverine is listed, the ESA does not provide the means to regulate for climate change impacts. If there are other species that can be saved by more immediate actions, it makes sense to devote the USFWS’ limited resources to them. But by any definition, climate change is imminent. 2035 is 25 years from now, and that’s nothing – just a few wolverine generations. We already see the ongoing effects of a warming world, and they loom even larger in the very near future.  Listing the wolverine won’t save the wolverine, unless ESA rules are revised; its fate will be decided in places like Cancun as the world seeks consensus on climate change mitigation, in the forests of Asia and Africa as villagers sell carbon credits in exchange for halting deforestation,  in China as the Chinese either duplicate old development patterns or chose to invest in alternative energy, and most of all in the living rooms and over the dinner tables of America, where individuals choose to look the problem in the face and do something about it, or turn away while the tidal wave crashes down on us and on our nation’s most iconic wildlife and ecosystems.

Rebecca Watters researches wolverines (gulos) and other large carnivores for the Northern Rockies Conservation Cooperative. She blogs about wolverines at The Wolverine Blog.

Essays in the Range blog are not written by the High Country News. The authors are solely responsible for the content.

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