When you think of cognitively adept animals, the first thing to come to mind is probably not a crow. But crows, according to new research, are some of the most skilled engineers in the animal kingdom.
The study, published this week in the journal Biology Letters, involved fitting 19 wild crows on New Caledonia Island, part of a small archipelago in the Pacific Ocean, with self-developed miniature video cameras that would record their every movement.
The lightweight "spy cameras," fastened on to the birds' tail feathers, caught something unexpected: in two instances, crows spent a significant amount of time fashioning a tool that would help them forage in tree crevices and holes more effectively. In both cases, the tool was described as a "hooked stick tool"—basically, a twig with a hook on the end that could help the animal pull or scrape material towards himself. If you look closely, you can see the crows fashioning their tools:
A screenshot of the video shows the crow with the tool in his mouth, using the hooked end to poke around inside a nook in a tree:
The researchers, who hail from the University of Exeter and the University of St Andrews, say that the findings, which were gleaned from hundreds of hours of crow's-eye footage, are telling—it's the first instance of this kind of behavior in the wild.
"While fieldworkers had previously obtained brief glimpses of hooked stick tool manufacture, the only video footage to date came from baited feeding sites, where tool raw materials and probing tasks had been provided to crows by scientists," co-author Christian Rutz told Phys.org.
What's more, the research shows that the crows attach value to their tools—in one scene, a crow dropped its tool and then recovered it from the ground, a sign that the tools were made for repeat use.
It's not the first time crows have exhibited tool use, however. Several studies have found that crows are in fact ingenious engineers—a testament to their surprisingly advanced cognitive abilities. One experiment even found that crows can figure out a three-step problem using tools.
Tool use has long been considered a marker of superior cognitive ability in animals—famously harking back to the discovery of chimpanzee tool use (the apes were using sticks to catch termites) by primatologist Dr. Jane Goodall in the 1960s at Gombe National Park. While crows do exhibit impressive tool use, primates, admittedly, are undoubtedly the champion tool-users in the animal kingdom.