Please Note: This is the first of two blogs about a research paper published today in Science Advances providing the first evidence of complex social strategies in any solitary carnivore—and showing that mountain lions in particular are more social than previously thought. Part Two will chronicle how territorial males structure social interactions among mountain lions.
Mountain lions—stealthy solo predators all muscle and grace—are known for going it alone, venerated by admirers of pioneers, adventurers, and entrepreneurs. But are these big cats as solitary as we once thought?
New research by Panthera’s Teton Cougar Project just published in the prestigious journal Science Advances suggests otherwise—that mountain lions might regularly, predictably, and even strategically engage in social interactions with their peers. Perhaps they should be venerated for their cooperative behaviors instead.
Consider F51 and F61, two adult female mountain lions followed by Panthera’s Teton Cougar Project, both of which have been central to our work in recent years as well as co-stars in the recent BBC film Big Cats in High Places and NatGeo Wild film Cougars Undercover.
On four separate occasions, F51 killed large prey and allowed F61—and her two kittens—to share the carcass. At the time, F51 also had kittens of an almost identical age. On six different occasions during the same time period, F61 killed large prey and, in turn, allowed F51 and her kittens to feed from her kills. Typically, the females took turns feeding at the carcasses, while the other lay nearby. Their kittens, however, fed with either mother.
In this video, two adult female mountain lions exhibit the characteristic hisses and posturing common during social interactions at a food source. The pair and their collective 7 kittens remained together for 3 days, but slept in separate areas during the daylight hours.
Traditionally, ecologists are quick to dismiss these sorts of associations as unusual, or explained by simple logic. Mountain lions and other solitary carnivores are supposed to avoid each other, and interact infrequently to mate or settle territorial disputes (See previous blog Solitary Is Not Asocial: Social Interactions Among Mountain Lions). “They must be sisters,” I was told again and again when I shared the news of F51 and 61 with friends and peers.
Determined to find answers, my research team and I conducted genetic tests in partnership with Anthony Caragiulo of the Sackler Institute for Comparative Genomics at the American Museum of Natural History. Unexpectedly, these results revealed that the females were unrelated. Questions exploded in my head, but few answers surfaced.
Consequently, I made social behaviors a priority in our research. Between 2012 and 2015, we documented an astonishing 118 interactions among adult mountain lions. That was surprising in itself. But perhaps more surprising was that 60% of these interactions occurred over entrees served up by one of the big cats—almost always a carcass of a large animal killed by one of the mountain lions in the interaction.
This unanticipated discovery also provided us a unique opportunity: We could assign a “direction” to mountain lion interactions at kill sites, which in our case was from the cat that made the kill to the cat receiving the benefits of social tolerance (tolerance means sharing a resource without fighting) and free food. Incorporating direction into social interactions allowed us to test for complex social strategies, like reciprocity, which until now had only been documented in social species like chimpanzees and humans.
This video represents one of the most aggressive interactions we recorded during our research on mountain lion social behaviors in northwest Wyoming. The aggression only lasted a minute and then F47 and F49 remained together for 1.5 days, alternating feeding on the carcass.
Any form of cooperation tends to come at a cost to the individual sharing or supporting another. This cost, however, can be neutralized if that individual is repaid through reciprocal behaviors in the future. Even better, individuals that engage in reciprocity typically come out ahead as compared to individuals that do not engage in cooperative behaviors at all—reciprocity is a smart social strategy. Many researchers, however, believe that animals lack the cognitive capacity for recalling experiences and the strategic thinking required to exhibit reciprocity; but, there is increasing evidence that many animals can and do exhibit reciprocity.
In collaboration with Dr. Mark Lubell and his PhD student Michael Levy at the University of California, Davis, we applied social science techniques (network analysis) to natural history questions. The synergy resulting from applying social science methods to wildlife research allowed us to unveil patterns characterizing mountain lion tolerance and food-sharing at mountain lion kills. We were shocked to realize that the strongest pattern was direct reciprocity. If one mountain lion allowed a second to feed from its kill, the second was 7.7 times more likely to allow the first to feed from one of their own kills down the line.
This means that everything we thought we knew about mountain lions—that they are solitary killing machines that only come together to mate or fight—was wrong. Instead, our analysis describes a secretive species with a complex social system built on reciprocal tolerance and food-sharing.
Mark Elbroch has received a conservation grant from the National Geographic Society to study cougars. His research was featured in an article, Ghost Cats, in the October 2013 issue of National Geographic Magazine. Learn more about the National Geographic grants program.
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