Aesop's fable "The Crow and the Pitcher" has been confirmed in a wonderful experiment. In the classic tale, a thirsty crow uses stones to raise the level of water in a pitcher until it rises within reach of its beak. This is no mere fiction - rooks, close relatives of crows, have the brains to actually do this.
The aptly named Chris Bird, along with Nathan Emery, gave four captive rooks (Cook, Fry, Connelly and Monroe) a chance to reach a small worm floating in a cylinder of water, with nothing but a small pile of stones sitting on the side. All of them solved the task, and Cook and Fry succeeded on their first attempt. They were savvy about the stones too, using exactly the right number to bring the water within reach and preferring larger stones over smaller ones.
The accomplishments of Bird's rooks are even more impressive ...