What is a group of crows called?

A murder, which sounds ancient and is essentially a joke that got out of hand. Most of these collective nouns come from fifteenth-century English books of hunting terms - the Book of Saint Albans printed a long list in 1486 - and many were invented as parlour wit for gentlemen rather than recorded from anyone's actual speech. An unkindness of ravens and a parliament of owls are from the same tradition.

The birds deserve better press. Crows and their relatives make and use tools, recognise individual human faces, and hold grudges - a famous set of experiments at the University of Washington had researchers wear a particular mask while trapping crows, and years later birds who had never been trapped, but had watched, still scolded anyone wearing it. The knowledge had been passed on.

New Caledonian crows manufacture hooked tools from twigs and carry favourites around between jobs, and in the laboratory one solved an eight-stage puzzle requiring tools to be used in sequence. On several measures of problem-solving they perform in the range of great apes, with a brain the size of a walnut built to a completely different plan.