Scientists, Jolyon Troscianko from the University of Exeter, and Christian Rutz from the University of St Andrews, have recorded how New Caledonian wild crows (Corvus moneduloides), located in the island of New Caledonia, use complex tools such as hooks in order to hunt for insects.

The new findings could be recorded because researchers attached minuscule spy-cameras to the crow’s tail feathers, to analyze the natural behavior of the complex birds thought to be as intelligent as a 7-year-old kid.

Researchers, who said the cameras have the same weight of a British 2-pound coin, and store the video footage on a micro-SD card that can save video recordings of remarkable quality, developed the recording devices said Christian Rutz.

A New Caledonian crow (Corvus moneduloides) uses a twig. Image credit: Jolyon Troscianko.

The team designed 19 cameras that were attached to the birds later, because previously they tried to film the crows while using hooked stick tools, but after hundreds of hours of fieldwork they couldn’t do it.

They were impressed with the findings because they had just obtained two brief glimpses with binoculars, of the animals using the tools. It appears in the videos that a crow spent a minute developing a hooked stick tool and then it tried to take food from tree crevices and from leafs that were on the ground.

Troscianko explained that while fieldworkers had previously obtained brief glimpses of hooked stick tool manufacturing, the only video footage to date came from baited feeding sites, where scientists had provided tool raw materials and probing tasks to crows, added the researcher.

“We were keen to get close-up video of birds making these tools under completely natural conditions. 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,” said Jolyon Troscianko from the University of Exeter, who published the findings in the journal Biology Letters.

The researcher said that the behavior the team recorded was easy to miss. He mentioned a time when he watched the footage and he did not see anything particularly interesting, but when he observed frame-by-frame he was impressed with the fascinating abilities of the intelligent animals.

Another interesting finding is that it appears crows value their tools since they don’t discard them after using them for a single time. In a video, a crow that drops its tool and then recovers it from the ground can be seen.

Christian Rutz from the University of St Andrews said the findings propose an evolutionary puzzle, he said it was intriguing that humans are very good at using tools but just a few animals use them. Researchers expect to learn what make the crows different from all birds, since they use tools in concrete situations.

“Some people think you need a large brain to use tools. These crows disprove that. They show incredibly complex tool behavior. The big question is: Why and how? What is special about the crows on this island?” said Christian Rutz, a behavioral ecologist at the University of St. Andrews in Scotland and coauthor of the study.

Source: Biology Letters