For about as long as humans have been studying animal behavior, though, they’ve been considering the question of whether such a love is really possible. Is it fair to call these pairings friendships, or is there something else that’s drawing them to one another?

Gordon Burghardt, a psychologist and ecologist at the University of Tenessee, dismisses the argument that animal friendships are just humans anthropomorphizing other behaviors. “Mother-infant bonding, no one has a problem extending that from a human to a chimpanzee,” he says. “I think if you’re careful, it’s pretty reasonable to extend behavioral similarities across species.”

And in recent years, the case for animal friendship has solidified: Chimpanzees choose their companions based on personality, elephants offer one another emotional support in times of stress, bats form cliques within their larger colonies—all elements of the bond that we call friendship when it’s shared between two humans.

But researchers aren’t as sure what’s going on with the star-crossed lovers of the animal kingdom—especially when these interspecies pairings are a predator and its prey. Over the past few weeks, for example, a tiger at the Siberian Zoo named Amur has been palling around with a goat, Timur, which handlers originally left in his enclosure as a meal. Amur had attacked and eaten all his previous goats; this one, though, spends his days romping through the tiger enclosure with his would-be killer. Here’s a video of the two animals at play:

“They are inseparable,” Dmitry Mezentsev, the director of the park, told The Siberian Times. Amur, who had never before been aggressive with park staff, has begun hissing at anyone who gets too close to Timur.

One possible explanation: At the moment that Timur entered his enclosure, Amur was lonelier than he was hungry. Animals in captivity have their food presented to them; they don’t need to worry about marking their territory or looking for mates the way an animal in the wild would. “All those activities take time and energy, and if those needs are removed, the animals get bored,” Burghardt said. Depending on the context, a playmate—even an unorthodox one—can be more satisfying than a meal: “In this particular situation, the animal’s motivation to engage socially and playfully maybe was higher in its need hierarchy than eating.”

A zookeeper from a different Siberian wildlife park recently told The Siberian Times that there’s “an 80-85 percent chance” that Amur will end up eating his new friend. But there’s also a chance, Burghardt explained, that the tiger has come to permanently think of Timur as something other than food, and that once a bond has been established, it can often preclude a predator from reverting back to its natural state. (To hedge their bets—or maybe to spare Timur the trauma—the zookeepers have switched Amur to an all-rabbit diet.)