Wild crows filmed making tools to catch their food

A species of crow living on a remote island in the South Pacific has been hailed as one of the world's cleverest birds after it was observed making a variety of tools which it uses to catch grubs and other insects in the wild.

Scientists have for the first time used miniature video cameras attached to the wing feathers of New Caledonian crows to record the detailed behaviour of the animals in their natural environment.

The cameras shot video recordings through the legs of the birds as they walked, hopped and flew between foraging sites on the ground and in the trees within their forest habitat. The study, published in the journal Science, found the crows made equipment from a variety of materials and even carried preferred tools from one area to another.

Christian Rutz, a zoologist at Oxford University, said: "When you study the birds in the laboratory you can see how smart they are but what you can't do is make sense of the potential ecological or evolutionary significance of their intelligence – why has the behaviour evolved in the first place?" He suggested scarcity of food on the island played a role.

The images collected from 18 different wild crows showed the birds making tools using leaves, twigs and grass stems to probe for insects . One crow used a stiff strand of grass to poke the ground, possibly looking for ants. It carried the tool with it when it flew from one patch of ground to another.

Sometimes the crows used twigs to probe the trees and branches for the large grubs of wood-boring beetles. On other occasions, they stripped off the serrated edge of a tree leaf to use the barbs as hooks to fish for food.