On May 5, 2012, the way I—and many other scientists—understood mountain lions changed forever. A few days earlier, data collected from F57, an adult female mountain lion we’d captured as part of Panthera’s Teton Cougar Project just the month before, revealed that she’d been in the same place for two full days, behavior typically indicative of having made a kill. When new data conveyed that another adult female mountain lion, F109, had closed to within 500 meters of F57’s position, I rushed out with Jake Kay, a project intern at the time, to set motion-triggered cameras over the massive elk carcass we discovered on location.
Some days later, I retrieved the cameras and reviewed the video footage in our office with anticipation—F109’s data indicated that she’d visited the kill and in fact spent some time there. Slowly I clicked on each video in succession, hopeful but aware that capturing an interaction between mountain lions on film would be like catching smoke in my bare hands. But at precisely 11:35 pm on May 5th (the day I set the camera), F57 trotted into frame under cover of darkness. She quickly backtracked and hissed loudly in the direction from which she’d come. F109 emerged on screen, walking stiff-legged and tall; F57 snarled and retreated to the left side of the carcass. F109 followed, closing the distance between them from ten yards to two. F57 instantly rolled onto her back; her four clawed feet aimed at the interloper. F109 hissed quietly, and then turned her head to the side, communicating mild submission. Then the video ended. I sat alone in the quiet that followed, hand still on the mouse, stunned by what I’d just seen. And then I shot my arms above my head, and yelled “YES” at the ceiling, as thrilled and surprised as if I’d just won the World Cup. Because in mountain lion biology, I just had.
Mountain lions are solitary carnivores, and in fact every wild cat, big or small, is considered solitary, except two: the African lion that forms great family prides most people are very familiar with, and cheetahs, which sometimes form male coalitions that hunt and work together to court females and defend territory. Ecology has a particular definition for “solitary,” when referring to wildlife; Solitary species do not cooperatively raise young, forage, mates, or defend resources from competitors or predators. Solitary carnivores are expected to interact infrequently, and these rare interactions to be about courtship or territorial disputes. Everything you ever read about mountain lions would suggest that F57 and F109 should have avoided each other. But they didn’t. So perhaps I’d caught something odd, something out of place in mountain lion society?
Not the case, as you can read in a new article just published in Current Zoology. Between May 2012 and March 2015, we documented 65 Male-Female, 48 Female-Female, and 5 Male-Male interactions among 12 overlapping mountain lions. We captured an amazing 59 of these interactions on film, 11 (17%) of which included courtship behaviors (see Rare Video Footage Shows the Dynamics of Cougar Courtship). We found that mountain lions interacted 5.5 times as often between December 1st and May 31stas they did between June 1st and November 30th each year, which makes sense, since elk form massive winter herds on feed grounds from December-May and mountain lions court each other during breeding between February and May (see A Fortress For Cougar Kittens).
Sixty percent of the mountain lion interactions we documented occurred over food—a kill made by one of the mountain lions. And contrary to everything we read about mountain lions, kittens were present at 60% of Female-Female and Male-Female interactions at kill sites. Courtship interactions were less common. We even documented three adult pumas feeding together on 5 occasions, and as many as 9 pumas at a kill, including youngsters.
In 1989, Sandell emphasized that solitary is not the same as non-social, and that all solitary wild cats are social to some degree. Researchers studying primates also offer useful insights applicable to solitary wild cats. They define solitary primates as those that look for food alone, but still maintain social relationships. So while the frequency with which we documented mountain lions interacting with each other is unprecedented and sheds new light on the social behavior of mountain lions, it is not enough to challenge their status as a solitary species; all evidence so far indicates that mountain lions (and most wild cat species) hunt alone.
Stay tuned for more on the social behaviors of mountain lions from Panthera’s Teton Cougar Project. This research is the first in a series of papers we are publishing on the subject—the next explores patterns of social interactions and attempts to explain why mountain lions interact with some frequency. For updates, photos, and videos of all the mountain lions followed as part of Panthera’s Teton Cougar Project, join us on Facebook.
Sandell M, 1989. The mating tactics and spacing patterns of solitary carnivores. In: Gittleman JL ed. Carnivore Behavior, Ecology, and Evolution. Ithaca, New York: Cornell University Press, 164-182.