Corvus

Corvus is a widely distributed genus of passerine birds ranging from medium-sized to large-sized in the family Corvidae. It includes species commonly known as crows, ravens, and rooks. The species commonly encountered in Europe are the carrion crow, hooded crow, common raven, and rook; those discovered later were named "crow" or "raven" chiefly on the basis of their size, crows generally being smaller. The genus name is Latin for "raven". The 46 or so members of this genus occur on all continents except South America, Antarctica and several islands. The genus Corvus makes up a third of the species in the family Corvidae. The members appear to have evolved in Asia from the corvid stock, which had evolved in Australia. The collective name for a group of crows is a "flock" or a "murder". In 2002, research found that some crow species are capable of not only tool use, but also tool construction. Crows are now considered to be among the world's most intelligent animals with an encephalization quotient equal to that of many non-human primates.