Supposedly solitary pumas actually hang out with their fellow big cats quite often, frequently coming together and hissing and snarling before settling down to share a delicious elk carcass.
That's the startling discovery made by scientists who recently tracked 13 pumas — also called mountain lions or cougars — and set up cameras at kill sites. They recorded dozens of peaceful social interactions between these elusive felines.
Pumas can live for more than a dozen years in the wild and have huge home ranges that can stretch for hundreds of miles. Scientists used to think that they lived lonely lives and only came together to mate or fight over territory.
"There was really no other reason to come together at all," says Mark Elbroch of Panthera. "People just made a lot of assumptions based on very little data, and those assumptions became mythology, even within the science world."
But in the journal Science Advances, he and his colleagues say they had reason to suspect that the social lives of these mighty carnivores might be more complex. New GPS tracking that let scientists watch the movements of these animals in near real-time was revealing inexplicable meetings.
In May of 2012, for example, Elbroch looked at the GPS tracking and saw that a female and her kitten had stopped at a certain location. He noticed that another female with three kittens of her own were moving in that direction. So he and a colleague raced to the spot in the woods and found a dead elk. They pointed cameras at it and later found that the females spent two days together feeding at opposite ends of the same carcass.
"They sort of just sat at either ends of the carcass and weren't particularly friendly to each other. They just sat there and ate. And the kittens would bounce in and feed when they could," says Elbroch. "I can't explain how exciting it was for me to capture, for the first time, an interaction between adult mountain lions. It was just so different than what I expected to happen."
And it turned out to be a common occurrence. When they followed 13 of the big cats from April of 2012 to March of 2015, they learned that every single cat participated in food sharing. "All the mountain lions participated," says Elbroch. "That in itself was shocking. There wasn't a lone mountain lion that didn't interact with anybody."
In winter, the cats seemed to get together with pals over a meal every couple of weeks, in feeding episodes that could last for days.
"We found very clear, very interesting patterns to who shared with who," says Elbroch. The most dominant was direct reciprocity: if a mountain lion shared with another, the recipient would later return the favor.
What's more, the mountain lions generally seemed to organize themselves into a couple of small communities defined by the territories of two dominant males. Cats within these areas socialized more frequently with each other than with outsiders.
All of this, says Elbroch, "completely redefines what we know about mountain lions."
The study found that males, in general, received much more free food than they shared with others. It might be that females got something else in return, such as building a relationship that would provide breeding opportunities or protection from other males that might kill their young.
Given that mountain lions have a complex social system apparently built on reciprocity, Elbroch says this raises the question of whether other "solitary" carnivores do as well.
He also would like to know what effect trophy hunting might have on these social structures. "What happens when a male is removed," he wonders. "Is there social chaos? Is there quick turnover to maintain those social systems and relationships that are in place? We don't know."