Only 7 percent of Jackson Hole’s mountain lions are surviving to adulthood, new research out of the Teton Cougar Project shows.
Mark Elbroch, the cougar project’s leader, relayed his team’s findings during a presentation Monday before about 200 people at the Center for the Arts. Passionate, animated and able to connect with a crowd, Elbroch used videos and anecdotes to tell the tale of the “secret lives of cougar kittens,” including the bumpy road they face on the way to maturity.
“In real terms, how many survive out of 100 kittens?” Elbroch said. “Thirty-four survive until they’re six months.
“And that’s actually as optimistic as we could make it,” he said. “That’s using survivorship analysis based on the last 13 years. If we just used the last six years, [survival] would be half that.”
Survival rates for Jackson Hole mountain lions are much improved for animals 6 months to 18 months old, but the young cats still face difficulties. Predation — the biggest killer of mountain lions until 6 months old — becomes a non-issue, but other threats in the valley’s rugged landscape come into play, Elbroch explained.
“Twenty [lions out of 100] make it until they’re 18 months old,” he said. “If, again, we use six years [of data] to do our survivorship analysis, only seven [out of 100] would survive.”
Over the life of the Cougar Project’s 13-year study, survival rates for young mountain lions have gradually declined.
Elbroch charted the decline on a graph that also showed increases in the wolf population within the project’s study area, which stretches from east of Jackson north to Buffalo Valley.
“You can see that survivorship has dropped as wolves have increased in the system,” the cougar project leader said. “And this correlation is perfect — 0.999, which is unheard of in wildlife work.”
The correlation between young cougars dying and wolves increasing held true both for lions under 6 months old and those 6 to 18 months old.
At least five mountain lion cubs mothered by Cougar Project research animals have been killed by wolves over the past few years.
In his talk, Elbroch walked the audience through the social lives of cougars from conception to birth, through development and eventually to dispersal.
Videos captured by remote camera aired during the 45-minute presentation and wowed the crowd. One clip, Elbroch said, featured the first footage ever of a wild mountain lion in a den.
Den selection, Elbroch said, is one of the most important decisions a mother lion makes when trying to safeguard her kittens.
“At the large scale, mountain lions want to be away from dangers — that’s people, wolves and bears,” Elbroch said.
“At the small scale, they want to choose a site that is like a fortress,” he said. “The importance of structure cannot be emphasized enough.”
Videos and photos the biologist displayed showed an impenetrable tangle of deadfall trees surrounding an “excellent” den site. Elbroch also presented images of a less effective den site — where kittens were killed.
At 5 weeks old cougar kittens typically start to leave the den and aren’t always under mother’s watch. In one instance, a Cougar Project research cat left her litter at the den for four days, Elbroch said.
“You can see the importance of those tiny holes [in the den site] now,” he told the crowd. “These kittens just disappear in the labyrinth that is this downfall, and that’s what protects them when their mother is away.”
The elements can do a number on cougar kittens when they are few months old.
“Those kittens born in fall enter the winter when they’re so small and when their ears are so thin they are particularly vulnerable to frostbite,” Elbroch said. “We’ve seen a number of kittens lose chunks of their tail and their ears.”
By 3 1/2 to 4 months old, cougar kittens are of an age where they’re ready to learn lion etiquette from mom, Elbroch said. Life becomes less about play, he said, and hierarchies develop within litters.
“This period in their lives, when they’re sort of mobile and yet not very quick, not very agile,” Elbroch said, “they’re particularly in danger of being killed by a predator.”
At 6 months old, young lions have gained agility, can climb trees and usually are able to evade wolves and bears.
Hunters and then starvation take the place of bears and wolves as the gravest threats to young adult lions.
“Predation ... is almost unheard of [for lions] from 6 to 18 months old,” Elbroch said. “In fact, the leading cause of death for [young adult] pumas in our study has been humans.”
The Wyoming Game and Fish Department — a collaborator on the Cougar Project’s research — allows for a total of five lions to be killed in the hunt unit that encompasses the project’s study area. The seven-month hunting season ends March 31.
The Teton Cougar Project estimates that 20 adult lions plus additional young dispersers and kittens call the study area home.
Elbroch could not be reached for an interview Tuesday before press time. He ended his presentation Monday on a less bleak note, airing more footage from the lion den.
“On average, in our study area, females give birth again 26.5 months after their first litter,” Elbroch said. “And the whole cycle begins again.”