These Crows Are More Clever Than Non-Human Apes When It Comes to Building Compound Tools

By Ryan F. Mandelbaum on at

Let’s say there is a fifty-pound note wedged behind a bookshelf just beyond your reach, and beside the shelf is a Meccano set. Even a toddler could probably snap together a few of the pieces to fish the note out. But what about an animal? One especially smart crow species seems to have figured out this problem on its own.

New Caledonian crows are heavy hitters when it comes to smarts, known for their play and advanced toolmaking skills. But a new paper shows the birds demonstrating toolmaking behaviour seen previously only in humans and captive apes: They assembled new tools from constituent parts.

“We wanted to know how inventive they are, whether they can solve a novel problem they don’t usually encounter by putting components together in order to reach,” study author Auguste von Bayern from the Max-Planck-Institute for Ornithology and the University of Oxford told Gizmodo. “It’s really testing their creative ability.”

The scientists began with eight wild-caught New Caledonian crows. First, they presented the crows with a transparent box containing food on a track, which, if pushed to the end, would come out of the box. They also supplied wooden dowels long enough to reach the food and push it along the track. This familiarised the crows with the task. Then, the researchers placed the food out of reach of the dowels and scattered combinable pieces on the floor near the crows and on a tool older—cylindrical pieces that fit into one another to create a longer tool.

Four of the birds (named Tumulte, Tabou, Mango, and Jungle) successfully created a longer tool from the pieces to retrieve the food. Three of the birds successfully solved the task again in follow-up trials, but Mango, “a bird with apparently fluctuating motivation” refused to participate in the followups according to the study published in Scientific Reports. The other four continued to aim at the food with the short rods and were disqualified.

The researchers continued subjecting the birds to these kinds of tests, but when the food was out of reach of a two-component tool, only Mango knew what to do: He made three- and four-part tools. It turns out that he was motivated enough to outperform his peers. The findings presented here “matches and exceeds present evidence for this ability in non-human primates,” the authors write.

This is a small study, of course, and does not observe the birds in the wild (though New Caledonian crows are well-known tool users, fashioning hooks to feed). But it’s still “truly amazing” that the birds figured the relatively complex task out. “It’s not surprising that chimpanzees can do stuff similar to human children,” said von Bayern, “but to find such similar feats in distant relatives suggests that they‘ve developed their cognitive abilities independently.”

The researchers are ultimately interested in how intelligence evolved, and how ecological factors can impact how cognitive ability evolves.

Who knows what the birds will learn to build next? Especially Mango. Watch out for him. [Scientific Reports]