Corvidae is a cosmopolitan family of passerine birds that contains the crows, ravens, rooks, jackdaws, jays, magpies, treepies, choughs, and nutcrackers. In common English, they are known as the crow family, or, more technically, corvids. Over 120 species are described. The genus Corvus, including the jackdaws, crows, and ravens, makes up over a third of the entire family.
They are considered the most intelligent of the birds, and among the most intelligent of all animals, having demonstrated self-awareness in mirror tests (European magpies) and tool-making ability (crows, rooks)—skills until recently regarded as solely the province of humans and a few other higher mammals. Their total brain-to-body mass ratio is equal to that of great apes and cetaceans, and only slightly lower than in humans.