13 january 2005

Young crows show natural tool-making talent

Young New Caledonian crows can make and use tools without being taught and without ever having seen an adult crow doing the same thing, according to research by Oxford zoologists, published in this week's edition of Nature.

New Caledonian crows are prolific tool-users, and are able to make their own tools from a variety of materials. Using four juvenile crows bred in captivity, the team demonstrated that the ability to make and use tools is at least partly inherited rather than taught.

The four young crows were hand-raised in an aviary containing twigs of assorted shapes and sizes, and food hidden in holes and crevices. The researchers gave regular demonstrations of how to use twig tools to retrieve food to two of the crows. The other two were housed separately and never witnessed tool use. All four crows developed the ability to use twigs to retrieve food, and there was no discernable difference in tool using ability between the two who had received demonstrations and the two who had not.

When presented with leaves similar to those used by crows in the wild to make tools, the young crows demonstrated the ability to make tools by cutting and tearing the leaves into a variety of shapes. However, none of these tools resembled the distinctive stepped shape created by wild adult crows, indicating that while some skills may be inherited, others are socially transferred.

Alex Kacelnik, Professor of Behavioural Ecology, and author of the Brief Communication in Nature, said: 'These results demonstrate that the ability of this species to manufacture and use tools is at least partly inherited and not dependent on social input. Although spontaneous tool use has been observed in many animals, to our knowledge, ours is the first report of spontaneous tool manufacture in a naïve juvenile vertebrate.'

'In the light of our findings, it is conceivable that the high level of skill observed in wild adult crows is not socially aquired. Social input, however, may be important in transmitting specific techniques and tool shapes.'