Backcountry recreation predicts where wolverines are scarce in Canada's Rocky and Columbia Mountains

Wolverines were already known to steer clear of busy ground ^[16]. That finding on its own describes animals shifting their ranges while the population holds steady. Barrueto's result is a claim about numbers. "That's on a population scale. It's not that they just avoided a small area; there were actually fewer individuals living there," she said ^[10]. "In areas with more disturbances, either road density or recreation, there were fewer individuals than in areas with less," she said ^[17].

The baseline is thin. Fewer than 300 animals across 81,800 square kilometres ^[4] works out to at most about 3.7 wolverines per 1,000 square kilometres, or at least 270 square kilometres for each animal ^[1]. The Upper Columbia region of southeastern British Columbia had very few, Barrueto said ^[15]. She estimated the population could be about 30% higher without current recreation and road levels ^[5]. Applied to the 300 ceiling, that is a difference of no more than about 90 animals ^[2].

Earlier studies had already found road density to predict wolverine numbers ^[7]. Recreation is the new variable. According to the phys.org account, this is believed to be the first landscape-scale study linking recreation to lower population density in a carnivore ^[2]. "I was a bit surprised by the impact of recreation, to be honest," Barrueto said ^[6].

The recreation variable comes from publicly available heat maps from recreational apps, covering backcountry skiing (heliskiing and cat skiing included), cross-country skiing and hiking in winter and summer ^[8]. A heat map counts the people who log their trips. The thing this doesn't tell you is how closely logged use tracks total use from one drainage to the next. If app users cluster in some areas, the recreation measure is skewed, and so is any effect size built on it. Snowmobiling is not in the heat maps; Barrueto said it is likely captured in the road density data ^[9].

The design compares places. More disturbance lines up with fewer wolverines. That pattern fits recreation driving numbers down, and it also fits people and wolverines sorting across terrain for separate reasons. The phys.org account does not describe how the animals were counted or what else the model held constant.

For managers, the most useful detail is the split by sex. Road density affects females the most ^[11], and females set the pace of recovery in an animal that has one to three young every few years ^[12]. "They're pretty small carnivores," Barrueto said. "It generally seems stressful for most of these animals to be interacting with a human." ^[18]

The paper's five recommendations include maintaining roadless and low-road-density areas, protecting low-disturbance, high-quality habitat, and limiting recreation in reproductive areas ^[13]. I think the evidence as reported supports the narrowest of these, limiting recreation where wolverines breed. It does not yet justify treating the 30% figure as a recovery target, unless the paper's controls prove stronger than the summary shows. "Our findings are stark," said co-author Aerin Jacob of the Nature Conservancy of Canada. "What gives me hope is that this gives us something to act on, at every level." ^[14]