Crow, (genus Corvus), any of various glossy black birds found in most parts of the world, with the exception of southern South America. Crows are generally smaller and not as thick-billed as ravens, which belong to the same genus. A large majority of the 40 or so Corvus species are known as crows, and the name has been applied to other, unrelated birds. Large crows measure about 0.5 metre (20 inches) long, with wingspans that can reach 1 metre (39 inches).
Crows live in large, close-knit families, and, like social mammals, they not only hunt and forage together but also defend territories and care for the young together. Most species, however, do not nest in colonies. Each mating pair has its own nest of sticks and twigs, usually high up in a tree. There are laid five or six greenish-to-olive eggs, with darker speckles. Young crows may spend up to six years with their parents before breeding on their own. As winter approaches, northern crows gather into large night-roosting groups. These flocks can include tens of thousands of birds and occasionally hundreds of thousands.
