Corvus

Corvus is a widely distributed genus of medium-sized to large birds 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 temperate continents except South America, and several islands. The Corvus genus 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". Recent research has found some crow species 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. Medium-large species are ascribed to the genus, ranging from of some small Mexican species to of the large common raven and thick-billed raven, which together with the lyrebird represent the larger passerines. These are birds with a robust and slender appearance, equipped with a small, rounded head with a strong, conical beak, elongated and pointed, with a slightly curved end towards the bottom; the legs are strong and the tail is short and wedge-shaped. The coloration of the livery is dominated by shades of black, with some species having plumage with metallic iridescence and others that have white or gray areas on the neck or torso. Australian species have light eyes, while generally the irises of other species are dark. Sexual dimorphism is limited. The members of the genus Corvus are believed to have evolved in Central Asia and radiated out from there into North America, Africa, Europe, and Australia.