JACKSON — Mankind has played an outsized role in driving down Jackson Hole’s mountain lion population, even without a concerted effort to cut back numbers of the large cats, new research says.
The mid-1990s reintroduction of wolves to the Greater Yellowstone Ecosystem, lion hunting and the redistribution and reduction of the Jackson Elk Herd were the primary factors affecting lion survival over a recent 15-year period during which Panthera’s Teton Cougar Project studied cats roaming a 550-square-mile swath of the valley from Jackson north to the Buffalo Valley.
“It’s interesting to try to untangle, because not all of [the factors] were intended to have any impact on mountain lions,” Teton Cougar Project leader Mark Elbroch said. “But they did.”
Elbroch, along with Lucile Marescot, Howard Quigley, Derek Craighead and Heiko Wittmer, wrote about the causes of mortality in a recent edition of the academic journal Ecology and Evolution.
Hunting’s role in influencing Jackson Hole’s pumas was expected, Elbroch said, because it’s the leading cause of death for the large carnivores “anywhere in the West.” Between 2002 and 2015 human hunting was the leading cause of death of Cougar Project-tracked adult cats, the study said.
Wolf reintroduction was another “management intervention” that had an unintended effect of killing lions, directly and indirectly. The large canines were the No. 1 agent of death for cougar kittens, taking an especially heavy toll on the young felines during winters. Wolves also are thought to have limited puma access to elk through competition, Elbroch said, pushing them off carcasses but also physically blocking them from the food resource.
“There’s not a mountain lion that’s going to wander out into the refuge amid wolf packs,” he said. “That’s really unlikely.”
Changes since the turn of the century to the Jackson Elk Herd were also deemed a major factor in the lion decline, simply because that major prey source was less available. Not only has the overall herd size fallen, from around 16,000 elk to 11,000, but fewer and fewer animals are depending on “native range” and are staying close to human-provided winter range: the National Elk Refuge and other elk feedgrounds. That dynamic was more pronounced than ever last winter, when 97 percent of the herd was either on the refuge or immediately adjacent.
“The trickling down effect to moving all the elk to one area is going to be dramatic,” Elbroch said.
“What I think is exciting about our research is it highlights the importance of elk on native range,” he said. “What it means to me is that wildlife managers and the community really need to think creatively and strategically and figure out, ‘How do we get elk on native range?’”
Wyoming Game and Fish Department carnivore biologist Dan Thompson said he agrees with many of the researchers’ conclusions. But hunting pressure, he pointed out, is already lower in Jackson Hole than anywhere else in Wyoming, meaning the fate of the region’s cats may hinge on the other factors.
“It will be interesting to see what happens going forward,” Thompson said. “It depends on what happens with wolves and elk. I don’t expect to see a high population density of mountain lions in the Gros Ventre.”
Elbroch thinks lion hunting ought to be reduced further to help prop up the valley’s cat numbers, which he said haven’t showed signs of leveling off. The maximum number of lions that can be killed in Game and Fish’s unit two — which encompasses Jackson Hole — is two animals. He suggested that hunt could be suspended and quotas in nearby areas could be reeled back as well to encourage cats to disperse into those areas.
“What I would like to see is [the population] level out,” Elbroch said. “That, I think, should be addressed in terms of conservation management.”
“If it was just wolves, that’s one thing,” he said. “Now it’s wolves, hunting and reducing elk. That’s why we’re seeing these dramatic declines.”