Wild crows are crafty with tools

Wild New Caledonian crow tagged with video camera. The camera lens is protruding through the central tail feathers.

Recording themselves on tiny video cameras attached to their tailfeathers, New Caledonian crows have revealed themselves to be resourceful tool-users in the wild.

These birds have been known to put on quite a show in the laboratory, performing ingenious tricks with tools for researchers’ cameras, such as bending a wire into a hook and using it to pull food out of a jar. But, researchers wondered whether crows behaved like this in nature, where the ability to use tools could be an important survival skill.

Video-camera unit for mounting on a wild New Caledonian crow.

To find out, Christian Rutz and colleagues at the University of Oxford attached cameras to wild New Caledonian crows. These birds have been difficult to observe because they are sensitive to human disturbance and live in forested, mountainous areas in the South Pacific, where it’s difficult to see them from a distance.

By analyzing the video footage, the authors were able to estimate how much food the birds actually ate (during an hour of foraging on the ground, the birds ate an average of eight small items, such as beetle larvae, small lizards and small fruits). They also found that the birds’ tool use and choice of tool materials -- sticks, dry grass-like stems -- were more diverse than previously thought, and that birds may keep particularly “good” tools for future use.

The authors proposed that video tracking should be useful for studying the behavior and ecology of many other bird species that are shy or live in inaccessible habitats.

This study will be published online by the journal Science at the Science Express website on Thursday, 4 October 2007.