New Caledonian crows can make their own tools and use them effectively

New Caledonian crows can make their own tools and use them effectively

Crows are intelligent and have been able to survive in diverse and difficult situations. Past researchers have proved that crows effectively use many tools. However, a technologically advanced species of crows, the New Caledonian crows, have been captured on camera making tools which they used for foraging. New Caledonian crows were captured in an interesting video by biologists while they were making hook-shaped tools.

Two biologists from the United Kingdom managed to record New Caledonian crows while they were making tools. Tiny cameras were attached to birds’ tail feathers and natural foraging behavior of crows was recorded in the camera.

The camera caught crows making and using hook-shaped tools for pulling out grubs, insects, larvae, and food items from crevices in logs. The study detailing the behavior noticed in the video has been published in the journal Biology Letters.

University of Exeter behavioral ecologist Jolyon Troscianko and Christian Rutz of the University of St. Andrews in Scotland worked on the current project.

"Crows really hate losing their tools, and will use all sorts of tricks to keep them safe," Rutz said in a statement. "We even observed them storing tools temporarily in tree holes, the same way a human would put a treasured pen into a pen holder."

Researchers have previously seen the crows making the tools in artificial situations, in which scientists baited feeding sites and provided the raw tools; but researchers say the New Caledonian crows have never been filmed doing this in a completely natural setting.

Dr Troscianko is a Postdoctoral Research Fellow in Exeter's Biosciences Department based at the Penryn Campus in Cornwall, who worked on the project while at the University of Birmingham.

He said: "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. We were keen to get close-up video of birds making these tools under completely natural conditions."

"New Caledonian crows are notoriously difficult to observe, not just because of the challenging terrain of their tropical habitats, but also because they can be quite sensitive to disturbance. By documenting their fascinating behaviour with this new camera technology, we obtained valuable insights into the importance of tools in their daily search for food."

The team deployed 19 cameras on crows at their chosen dry forest study site, where in hundreds of hours of fieldwork, despite two brief glimpses with binoculars, they had never managed to film crows manufacturing hooked stick tools.

The team were excited to record two instances of this behaviour on footage recovered from ten birds in their latest study.

Troscianko noted: "The behaviour is easy to miss - the first time I watched the footage, I didn't see anything particularly interesting. Only when I went through it again frame-by-frame, I discovered this fascinating behaviour. Not once, but twice!"

A crow uses a twig with a V-shape in it to make the tool. The bird snaps the stick in two places, just above the joint where the twig branches and just below it. That joint then forms a small hook at the end of a long, handle-like stick.

To shape the tool, the bird peels bark off the stick, removes any leaves attached, and will work the end to fashion it into a sharp hook.

This process takes the crows about a minute, says Dr. Troscianko. But it's an ongoing process.

New Caledonian crows (Corvus moneduloides) are found on the South Pacific island of New Caledonia.

Image Source: Jolyon Troscianko