New Caledonian crows are increasing their food searching skills by using hooks instead of merely straight twigs, says the journal Natural Ecology and Evolution.  The six scientists behind the study, show and explain how these crows are perfecting their natural skills when it comes to food retrieving.

The study explains the variety of tool types the crows use, the comparison of the time each one takes, their efficiency, methods and ecological benefit of the innovation.

New Caledonian crows hooked tools, New Caledonian crows use of tools, Crows food retrieving skills
These birds reshape twigs to better hunt their prey. Image credit: Joylon

Professor Christian Rutz, being the one that explains the discovery to BBC News, shows how the crows create with a lot effort a very precise and sharp small hook at the end of a specific type of twig to smack the prey.

Small Birds, Great Inventors

The New Caledonian Crows are medium-sized black birds that feed themselves, along with nuts and sees, with a wide variety of invertebrate animals, like small mammals, snails, and grubs.  The method these crows employed to hunt their larvae (found in crevices or nooks), before their hook invention, consisted of poking the prey with a twig, making the grub agitated leading it to bite the tool. The crow then proceeded to pull it out with the grub still on it, biting.

This poking method already meant that the New Caledonian Crow was capable of using tools. In the study, the researchers explain how the crows used hooked tools, and non-hooked instruments were treated by the birds to make them precise.

This all leads to the professors and biologists to believe that this alternate way of improving abilities helps to explain the evolution of tool manufacturing skills, caused by the determinant need for food intake.

The ‘new’ findings

The publication in Nature Ecology and Evolution describes how the crows made the fantastic hook-tool out of plant material, to capture their living food more efficiently. The crows would optimize their hunting time by even ten times, which allowed the scientist to register the effectiveness of the new method.

Professor Rutz, in an interview with the BBC, showed a twig with a very sharp v-like end and described the process of the crow to make its hunting tool. The crow picks a specific twig that’s already partially hooked at the end, then proceeds to tear small fibers from it, so it becomes sharper and pointier. Then Rutz shows how the crow tests the tool, which has a long straight part for the bird to hold it and a small pointed end to take its prey. Usually a grub, out from the cavity it is hiding.

This all means for them a new technology, a bigger step regarding the evolution of these creatures and animals in general. The New Caledonian Crow is the only animal known to be capable of making hooks. Professor Rutz even declared:

“When you think that we went in that 1,000 generations from crafting fish hooks to building space shuttles – that’s absolutely mind-boggling.”

The results provide them a new source of enthusiasm for studies that involve models that are not just for humans to study humans. The skill shows how the process of making a tool out of natural materials helps to understand, according to Professor Rutz, the foundation for evolving technology and what was the reason for it to happen.

Not the first study?

James St. Clair, Barbara Klump, Shoko Sugasawa, Caitlin Higgott, Nick Colegrave and Christian Rutz, the researchers, claim at the end of the study that it is their finding. However, the hooked-tool theory was previously published in a 2002 report by Alex Kacelnik, Alex Weir, and Jackie Chappell.

New Caledonian crows hooked tools, New Caledonian crows use of tools, Crows food retrieving skills
Previous research had already found the crows’ shaping skills. Image credit: Delhi Daily News

In 2002 the Oxford University study already showed the New Caledonian Crows were making hooks out of other materials, such as wire. They explain:

“The surprising thing about our crow is that faced with a new problem, she worked out a new solution by herself… In the wild, New Caledonian crows make hooks by working on twigs, but they live in social groups and follow age-old techniques in response to problems that the species may have been exposed to for thousands of years.”

They describe how their crow Betty, during an experiment, selected a bent cable instead of a straight one for collecting pieces of a pig heart. It was the first time Betty used a wire. Then, they started to give to Betty only straight cables which she ultimately bent up to nine times.

“To solve a new problem, she did something she had never done before. Naturally, she must have exploited abilities she acquired doing other tasks in the past, but she showed the capacity to solve a new problem in a creative way by reorganizing her experience” concludes Kacelnik.

A resume of this study, made by Robert Winkler, can be found in National Geographic.

Source: BBC News