Shaping of Hooks in New Caledonian Crows
A. A. S. Weir, J. Chappell, A. Kacelnik
Science 297, 981 (2002)
In the Brevia section of the 9 August 2002 issue of Science, Weir et al. report a remarkable observation: The toolmaking behavior of New Caledonian crows. In the experiments, a captive female crow, confronted with a task that required a curved tool (retrieving a food-containing bucket from a vertical pipe), spontaneously bent a piece of straight wire into a hooked shape -- and then repeated the behavior in nine out of ten subsequent trials. Though these crows are known to employ tools in the wild using natural materials, this bird had no prior training with the use of pliant materials such as wire -- a fact that makes its apparently spontaneous, highly specific problem-solving all the more interesting, and raises intriguing questions about the evolutionary preconditions for complex cognition. The crow's behavior was captured on an unusual video clip, available on Science Online.