Everyone has heard the story of about thirsty crow that can't reach the water at the bottom of a bucket. Instead of tipping out the water, the bird collects rocks and drops them in the bucket, slowly raising the water level until it's high enough to drink. It's a good fable and it demonstrates the necessity of innovation, but it always seemed just a bit too clever to be based in reality. As it turns out, the crow might very well have been a rook and the fable may be based entirely on fact.
Dr Nathan Emery and his team at the University of Cambridge presented four rooks with the problem from the fable. They left a floating worm in a glass of water too low for the birds to reach. They also gave the birds a small pile of rocks and watched the birds select the largest rocks and drop them in the glass to displace the most water. Of the four birds tested, two solved the puzzle immediately, while the other two were able to do it on their second try (though it doesn't say how they failed the first time around).
According to Dr. Emery, rooks no longer surprise him with their problem solving because over the last few years he has seem them make some astonishingly clever decisions when faced with complex tasks. They rival orangutans in their ability to use tools and solve physical problems. Corvids, the group of birds to which rooks belong, are known to use tools in the wild to extract grubs from logs, much the way monkeys are known to do. It's just good to know that being clever and innovative crosses species lines as a tactic toward getting what we want.