Cougar Kills

A pine marten dines on a piece of a moose calf scavenged from a carcass left by a mountain lion in 2013. The small mustelid is one of 39 species that have been documented using lion kills.

An incredible diversity of wildlife — from chickadees to grizzly bears — make use of cougar-killed carcasses that are distributed around the mountains and valleys of Jackson Hole.

Remote cameras left at carcass sites by Panthera's Teton Cougar Project over four years found that magpies and red foxes were by far the most common scavengers gleaning lion leftovers. But some 39 species were documented in total, a finding that surprised not only Cougar Project leader Mark Elbroch but the larger scientific community.

“We documented a greater diversity of scavengers than any other study in the world to date,” Elbroch said.

A synthesis of the Cougar Project’s findings was published in the latest edition of the scientific journal Biological Conservation. Elbroch, Connor O’Malley, Michelle Peziol and Howard Quigley co-authored the study, titled “Vertebrate diversity benefiting from carrion provided by pumas and other subordinate, apex felids.”

A number of behavioral and physiological traits in cougars explain why lion-killed carcasses are a major draw for other species: their timidity in the face of other large carnivores, small stomachs, hunting style and a tolerance of small scavengers.

“It seems like they have evolutionarily evolved to be able to tolerate big loses of food,” Elbroch said. “It’s pretty remarkable.”

If a mountain lion kills, say, an elk, the cat tends to bed nearby and allow all sorts of scavengers to come in, he said. It’s a different story with species like wolves and bears, which tend to clean up carcasses immediately or bed almost on top of them while guarding food.

The data bears out the different styles of storing food. The Cougar Project’s 242 motion-sensored cameras deployed from 2012 to ’15 found three times more scavenger species at lion kills than at carcasses left from wolves or humans.

A statistically significant portion of all the animals that call Jackson Hole home were drawn to lion kills. Elbroch and colleagues detected 28 percent of all mammals in the valley and 11 percent of bird species.

Not all critters recorded were eating left-behind flesh. A mole gathered elk hair and constructed a nest made entirely of wapiti insulation. A ruffed grouse was clearly eating, but perhaps was swallowing something other than ungulate meat.

“With the birds,” Elbroch said, “it’s tough to tell. Is it eating insects off the carcass or the carcass itself?”

What species surprisingly didn’t make an appearance?

“Given the number of cameras we had on the landscape sitting on free food,” Elbroch said, “I think it’s important to note that we didn’t ever detect a wolverine or a Canada lynx.”

While the Cougar Project’s research may lead to the suspicion that mountain lions are purposely wasteful or picky, that’s not the case, Elbroch said. In the wintertime snow and ice often claims carcasses by covering them up and locking them in. Come summer, bears steal half of all lion carcasses.

“And they also get full,” Elbroch said. “We’ve seen up to 18 days on an elk carcass, but even then they just get so full. They’re like little balloons.”

The Teton Cougar Project’s paper is attached to the online version of this story at JHNewsAndGuide.com. The study lists the entire suite of documented scavengers, from dark-eyed juncos to bushy-tailed woodrats.

Contact Mike Koshmrl at 732-7067, env@jhnewsandguide.com or @JHNGenviro.

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