Cambridge, UK - In Aesop's fable The Crow and the Pitcher, a thirsty crow uses stones to raise the level of water in a pitcher so it can reach it. In a study from the University of Cambridge, researchers demonstrate that rooks, which belong to the crow family, can do exactly that.
Lead author Christopher Bird (yes, really) commented: "Corvids are remarkably intelligent, and in many ways rival the great apes in their physical intelligence and ability to solve problems. The only other animal known to complete a similar task is the orang-utan."
The four rooks used stones to raise the water level to reach a worm floating on top. The birds were highly successful, regardless of the starting level of the water and the number of stones needed. Two got it right on their first try, whilst the other two birds needed a second go.
They were also highly accurate, adding the exact number of stones needed to raise the water level to the necessary height. Rather than attempting to reach the worm after each stone was dropped, they even apparently estimated the number needed from the outset, and waited until the appropriate water level was reached before dipping their beaks into the tube.
In the second experiment the rooks were presented with stones which varied in size. The rooks selected larger stones over smaller ones - although not straight away.
In the third experiment, the rooks appeared to recognise that sawdust couldn't be manipulated in the same way as water. When given the choice between a tube half-filled with each, they picked the water.
The study is published in Current Biology. We're really hoping they move on to Androcles and the Lion next.