Ravens cooperate with friends not foes

Ravens spontaneously cooperate to solve problems, but prefer to do so with some individuals over others

We often use the phrase 'birdbrain' as a mild insult, to mean someone who is dim-witted or acts stupidly. Birds' brains are indeed much smaller, and far less convoluted, than our own, but our feathered friends have had a bad press, and some of them - the corvids, in particular - are capable of remarkable feats of intelligence.

Crows, for example, can apparently contemplate death, and have tool-making abilities that are at least as sophisticated as, or may even surpass, those of monkeys. And Clarke's nutcrackers can harvest tens of thousands of pine seeds, and cache them in thousands of different locations. If they notice another nutcracker watching them burying their food supply, they return later on to hide that cache elsewhere. When winter sets in, they can retrieve the seeds from all the locations, relying solely on spatial memory.