

If you’re not yet obsessed with crows, you’re behind the times. A flood of research on the birds keeps turning up astonishingly smart behavior. They use tools: in artificial captive situations, in the wild, and by exploiting urban features like traffic. They recognize human faces. They can solve complicated multi-step puzzles.

Despite all the ability, current research barely scratches the surface of the Internet’s love affair with these animals. Floods of anecdotes and videos attribute everything from gratitude to playfulness to the corvid family—colloquially known as crows. We can even watch them appearing to find entertainment in tormenting other animals, like these apparently mischievous (or sadistic) crows causing a cat fight.

It’s hard to escape the feeling that this playfulness tells us something important about crow intelligence—it seems intuitive to take it as a further sign of prodigious animal intellect. The problem is, animal behavior is notoriously tricky to interpret. We have a tendency to project our own minds onto animals, says Alex Kacelnik, a professor of behavioral ecology at Oxford University. “We see animals doing things for which we don’t have appropriate explanations other than pretending we ourselves are doing it.”

In other words, we see crows playing on a snowy car or sledding down a roof and imagine why we would do something like that. We watch a crow apparently intentionally torment cats until they obligingly start clawing and notice the weird resemblance to Mean Girls. But what do crow researchers make of these anecdotes—can they really tell us anything about crow intelligence?

Yanking the tail

Let's start with the cat-fight. The crow seems nothing short of obsessed with the cats’ tails—behavior that’s pretty standard for crows, says crow researcher Jennifer Campbell-Smith. If crows see a tail, she writes, they pull it. “It’s like they can’t help themselves.”

It may seem like pure playfulness, but Campbell-Smith has observed the behavior in multiple different corvid species. She says that tail-pulling usually seems to be about stealing the other animal’s food. Nicola Clayton, whose research career at Cambridge University has centered around the strategies crows use to find and save food, agrees.

In some cases, the food stealing seems to be planned by two individuals. “I’ve seen a jackdaw pull a rook’s tail while another jackdaw comes around and [steals] its food,” Clayton says. The distraction strategy, she explains, is not all that different from pickpockets in crowded urban areas.

It’s a good example of a behavior with widespread anecdotal evidence and the appearance of intelligence and complexity. Overall, there are few animals capable of distracting another individual to steal its food—for most species, food-stealing is always just opportunistic.

Actually distracting an animal seemingly means that the thieving crow needs to figure out its victim’s current mental state (probably paying attention to its food), the effect the tail-pulling is likely to have on the victim (distraction from the food), and how the victim is likely to behave (turning around to see what’s happening to its tail). This capacity to decipher another individual’s mental state is known as theory of mind.

There’s also planning for the future in this anecdote. A cunning crow needs to know what it plans to do when its victim whips around. And in the case of a joint attack, two crows need to coordinate their movements with one another.

So tail-pulling appears to be a complex, intelligent behavior—or we could be falling into the trap Kacelnik describes, of attributing human-like minds to animals where other explanations could work just as well. It can be difficult to tell which explanation is best, but a good place to start is to look at whether other evidence suggests that crows are capable of such complex mental machinations.

Reading minds

It’s not outlandish to suggest that crows have the theory of mind needed to distract another animal and steal its food. Clayton studies the strategies crows use to find, save, and protect food, and she has found evidence of theory of mind in these behaviors.

For instance, a common behavior in many species is creating hidden caches of food to return to later. Some species remember where they’ve hidden their food, while others just rely on stumbling across caches by chance. When Clayton started out in crow research, it still wasn’t even clear that crows were among the species that remember their caches.

But it turned out that they weren’t just remembering where they’d hidden their food; they were remembering when they’d hidden it and whether the food was still fresh. Clayton found that scrub jays, a species of corvid, didn’t bother returning to caches that they knew had passed their use-by dates.

Even more impressively, she found that the jays also paid attention to who happened to be around when they cached their food and how that impacted the safety of the cache. If a crow cached its food and knew that another crow was observing it, it was likely to go back at a later stage and move the cache—but it depended on who was in the audience.

“They only do it if the onlooker is a threat,” says Clayton. “If the onlooker is a mate with whom they share caches, they don't bother to do it.”

This suggests not only that crows can distinguish between individuals but also that they can guess what those individuals intend to do with their cache. The birds recognize a friendly individual who won’t steal the food or a competitor who will. Doing this requires theory of mind. And since crows seem to have these abilities in their caching techniques, it’s feasible that they could use them to distract by tail-pulling, too.

Throughout these behaviors, there’s another ability at work: forward planning. Based on the benevolent or nefarious intentions of the crows in the caching audience, the crow hiding its food needs to be able to plan. What do that crow’s intentions mean for the safety of the cache? Should it be moved or kept where it is? It seems that experience on the thief’s side of the equation is helpful in making the call, and it takes a thief to know one, according to Clayton. “Only those that have themselves been experienced thieves know to move their caches to new places once they’ve been observed by thieves.”

It also seems that this behavior isn’t based just on a visual trick, because corvids are equally capable of being sneaky with what other crows can hear. “If another bird can hear them but not see them, they become as quiet as a mouse and only hide things in places that don’t make noise,” says Clayton.

Another of Clayton’s experiments with scrub jays found further evidence of forward-planning ability. The birds were kept in a food-free enclosure overnight and then released into one of two different enclosures in the morning: one where there was breakfast, another with no food.

After six days of training—three days in each enclosure—they were given the freedom to roam all three enclosures and the opportunity to cache food in both the breakfast and no-breakfast enclosures. They cached more than double the food in the no-breakfast room, suggesting that they were planning for the future food shortage in that room.

It’s feasible, then, that crows’ tail-pulling behavior is as complex as it looks. If we have other evidence that crows use theory of mind and forward planning in other food-related behavior, there’s no reason to think that couldn’t apply to tail-pulling, too.

Listing image by Jennifer Campbell-Smith