Imagine the plight of M56, the intrepid wolverine who made it to Colorado from northern Wyoming in 2009: alone, ranging through some of the most rugged territory in the Lower 48, wandering vast country in search of another of his kind, who most likely isn’t there. Wolverines were apparently wiped out of the Rockies, with the exception of isolated pockets of Montana and Idaho, by predator poisoning programs in the early 20th century, and when M56 dove off the edge of known wolverine habitat and struck out for the southern Rockies, he was recolonizing uncharted territory. Anecdotal reports of other Colorado wolverines exist, but as far as we know – scientifically speaking – M56 is the only gulo in the state. The nearest known breeding population is in the Tetons, which means M56 is adrift in an empty land. As Jason Wilmot said in a wolverine presentation in November, “If there’s a female wolverine in Colorado, he’s the one who’s going to find her.” The fact that M56 has not stuck in one territory, instead ranging throughout the Colorado Rockies, suggests he’s still looking. Poor guy.
But perhaps his quest will have a happier ending, thanks to a Colorado Division of Wildlife proposal to consider reintroduction of wolverines to the state. The proposal is still just that: an option to be considered, and not a definite plan. Some articles are quoting the proposed number of wolverines at 30 to 40, which would probably give M56 more companions than he could deal with. The earliest that the reintroduction would occur is 2012, and funding, among other details, has yet to be dealt with.
The inclusion of Colorado as wolverine range in the listing decision probably wasn’t coincidence; even without talk of a reintroduction, M56’s jaunt was attention-grabbing. Some people have suggested that female wolverines are incapable of making similar forays, but I asked Jeff Copeland about this back in November, and he said that it’s not necessarily true that female wolverines can’t make those epic excursions – it’s just that so far, they haven’t been documented doing so. Why? Female wolverines occupy the nearest vacant territory to their birthplace. They’re motivated to go only so far as they need to, until they find a territory that can support them and hopefully offer enough nutrition for reproduction. A male, on the other hand, will keep going until he finds a territory that encompasses a female’s, because life is going to be kind of pointless for him, in an evolutionary sense, if he doesn’t. The ratio of males to females is about 1:2; that is, a male tends to overlap with two females, so there’s a lot less room on the landscape for males. Hence, males have to go further.
But females do make impressive movements, which dim only in comparison to M56’s tremendous trek. To recolonize all of the US Northern Rockies, female wolverines have made some major journeys already, some of which we know about, some of which we can infer based on distance between occupied ranges. Females seem just as capable of continuing until they get to a good spot, and if the nearest good, vacant spot happens to be in Colorado, I wouldn’t be surprised if a female wolverine could make it. So put the talk of reintroduction aside, and you still have a distinct possibility of wolverines establishing a breeding population in Colorado on their own.
Still, that would leave a lot to chance, and the science, as summarized in the listing decision, highlights the risk of increasing temperatures and diminishing snowpack as a barrier to connectivity for wolverines in the Rockies. Year by year, wolverines of either sex will be required to disperse over greater distances in search of smaller patches of suitable habitat. Unfortunately, we still don’t have an assessment of the wolverine population in Wyoming – only the Tetons and Yellowstone National Park have been studied so far; the Tetons have a breeding population, Yellowstone has very few animals and no reproduction has been documented – so we don’t even know how many juveniles are potentially available to serve as a source population for a natural recolonization of Colorado. Coming to any conclusions about how and when a natural recovery might happen is difficult, and even if one or two females did make it, there would still be issues of genetic bottlenecks.
Reintroduction, proponents might argue, will give a boost to a natural process, and might stave off some of the effects of climate change by preemptively establishing a population node in a large chunk of suitable habitat. Significantly, according to local-scale climate models, the Colorado Rockies will retain spring snowpack in a hundred years, so the region could be critical to wolverine survival. Colorado hasn’t indicated a definite source population for the proposed reintroduction, but hypothetically, if they came from Canada or Alaska, which have the most robust wolverine populations in North America, the infusion of genetic diversity would be good for the overall Rockies population. (On the other hand, scientists estimate that a population node, in isolation and without connectivity to other nodes, would need 400 breeding pairs to maintain enough genetic diversity to survive. Colorado is not going to support 800 reproductive wolverines, so over the long term, unless there really is connectivity with Wyoming populations, we still have a problem.)
Scientifically, the reintroduction proposal is compelling. Endangered species, however, are among the most socially contentious topics in the Western US, and carnivores tend to raise the most heated passions on both sides of the debate. The on-going, wearying arguments about wolf and bear management are all the illustration one needs; no one wants to see wolverines disappear into the black hole of symbolic politics. M56 needs friends, but he needs human friends – or at least, people friendly to the reintroduction proposal – as much as he needs gulo friends. The ski industry and other individuals are already raising concerns about the impacts of a reintroduction.
Luckily for M56, we are dealing with an animal that is significantly different from wolves or bears, and the concerns that people might have can be addressed. But before we proceed with putting wolverines on the ground, or even advocating for the reintroduction, we owe it to M56 and wolverines throughout the Rockies to make sure that the social process is adequately carried out. The Colorado Division of Wildlife has been meeting with stakeholders to discuss concerns, as reported in the press, and so far, environmental advocates don’t seem inclined to make this into a rectitude-based battle of values. These are promising signs. If the reintroduction does go forward, I hope that it not only reestablishes wolverines in a crucial part of their historical range, but that it’s done in a way that can serve as a positive model of endangered species conservation in the West – something that’s as badly needed as another thriving population node of wolverines.