In tests at the University of Cambridge in England, four hand-raised rooks were able to make hooks out of wire, whittle sticks and choose suitable stones for different jobs, said Chris Bird, the zoologist who led the research.
The results suggested rooks -- members of the crow family -- have a high degree of innate intelligence rather than mere adaptability, Bird told The Times of London in a story published Tuesday. "These are fantastic findings," he said.
All four birds succeeded at challenges designed to obtain food from glass tubes. One test featured a worm on a platform that would collapse, allowing the worm to be eaten if a stone of the correct size was pushed into the tube. Other tests involved pruning twigs to fit into tubes and using a large stone to release a smaller stone to use in the tube.
"Rooks have been shown to rival chimpanzees in physical tasks, leading us to question our understanding of the evolution of intelligence," Bird said.