In May of 2012, the way I—and many other scientists—understood mountain lions changed forever. Data collected from F57, an adult female puma we’d captured 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 puma, F109, was within 500 m of F57, I rushed out 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. The data from F109’s collar indicated that she’d visited the kill and spent some time there—would the footage confirm it? I slowly clicked through each video, 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 slightly. 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 stunned silence, my hand still on the mouse. 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 had.
Pumas are solitary carnivores, and in fact every wild cat, big or small, is considered solitary, except two: African lions, which form great family prides, and cheetahs, which sometimes form male coalitions that work together to hunt, court females, and defend territory. Ecology has a particular definition for “solitary” when referring to wildlife; Solitary species do not cooperatively raise young, forage, mate, or defend resources from competitors or predators. Solitary carnivores are expected to interact infrequently, and researchers expect these rare interactions to be about courtship or territorial disputes. Everything I’ve ever read about pumas would suggest that F57 and F109 should have avoided each other—but they didn’t. So perhaps I’d caught something odd and 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 a total of 118 interactions among 12 pumas and captured half of them on film. 11 of the filmed interactions included courtship behaviors (see below). We found that pumas interacted 5.5 times as often between December and May as they did between June and November, which makes sense given massive elk aggregations during the winter months and breeding activity among pumas from late winter through spring.
In 1989, Sandell emphasized that solitary is not the same as asocial, and that all solitary wild cats are social to some degree. Researchers studying primates define solitary primates as those that look for food alone but still maintain social relationships; the same insights are applicable to wild cats. While the frequency of puma interaction we documented is unprecedented and sheds new light on the social behavior of these big cats, it is not enough to challenge their status as a solitary species; all evidence so far indicates that pumas (and most wild cat species) hunt alone.
This research is the first in a series of papers Panthera’s Teton Cougar Project is publishing on the social behaviors of pumas—the next explores patterns of social interactions and attempts to explain why mountain lions interact the way they do. Stay tuned!