Rooks

Christmas is over, the decorations are down and now it's back to the usual routine - or at least it will be once the accounts are finally handed in tomorrow. Rosie and I had a breezy walk round Ferry Meadows, where a large flock of rooks were busy feeding on earthworms in the rain-sodden grass.

Many people think that rooks are ugly and associated with evil. But such people haven't truly looked at them - in the sunshine their feathers have a rich purple and blue sheen. And like many other members of the crow family, they have an outstanding innate intelligence, demonstrated by research on hand-reared rooks, reported here by The Guardian.

Hand-reared rooks have been caught on video demonstrating tool skills that rival those of more sophisticated animals such as chimpanzees.Researchers at the universities of Cambridge and Queen Mary, London, recorded how rooks reacted when provided with a choice of tools and a problem to solve. All had been raised in captivity, so had not been taught any tool tricks by their parents.

The birds almost always selected the right tool to use first time, allowing them to crack the puzzle and retrieve tasty morsels of food. In one round of tests, the birds had to select a stone of the right size and drop it down a tube to open a trap door and release a little snack. In later tests, the birds had to choose sticks and stones of the right weights and sizes to retrieve snacks, and even use one tool to get another.

In the most impressive display of avian intelligence, the rooks were faced with a juicy worm in a tiny bucket at the bottom of a glass tube. Each bird looked at the worm and then bent a length of wire left nearby into a hook and used it to haul the bucket up.

Corvids are among the most social of bird species, and it is thought their intelligence helps them to recognise each other. The birds do not appear to have evolved tool skills, but are simply intelligent enough to work out how they can help.

Nathan Emery, an expert on animal cognition at Queen Mary, said the test involving the worm at the bottom of a tube could be the "first unambiguous evidence of animal insight", since the birds set about making hooks from wire before trying any other way to retrieve the food. "The finding is remarkable because rooks do not appear to use tools in the wild, yet they rival habitual tools users such as chimpanzees and New Caledonian crows," said Chris Bird, a Cambridge zoologist who led the study.

The study, which appears in the journal Proceedings of the National Academy of Sciences, challenges long-held views over the evolution and uniqueness of certain forms of intelligence.

Commenting in the journal, the authors say their findings overturn the idea that our own species' intelligence improved dramatically once early humans began working with tools. "Caledonian crows and now rooks have been shown to rival, and in some cases outperform, chimpanzees in physical tasks, leading us to question our understanding of the evolution of intelligence," they write.