A crow is any of a number of large black birds related to the ravens and jays. Crows occur throughout the nonpolar lands except South America, New Zealand, and most Pacific islands.
The well-known American crow (Corvus brachyrhynchos) of North America and the carrion crow (C. corone) of Europe are typical crows. They are 19 or 20 inches (48-52 cm) long and have black plumage with steel-gray reflections.
Crows favor woodlands and open farmlands. Their diet consists of a wide range of vegetable and animal matter, including carrion, insects, seeds, fruit, the eggs of reptiles and birds, young birds, and small reptiles. The small fish crow (C. ossifragus) of the Atlantic coast of North America also feeds on small fish and shellfish. Since crows often destroy cultivated crops in their search for food, they are not liked by farmers and are frequently killed. Crows are, however, intelligent as well as bold and wary. They adapt readily to changed conditions, and in spite of their persecution by man, they have been able to coexist with man in his spreading civilization and to thrive in areas greatly altered by man's activities.
Crows are known for their gregarious habits. When not breeding, they tend to congregate and sleep in flocks numbering as many as 40,000 individuals. One small European species, the rook (Corvus frugilegus), often nests in large colonies; hence the term "rookery," now often applied also to large herds of seals and other animals. Crows' calls are usually loud and harsh. Some species can be taught to repeat phrases clearly, similar to mynahs and parrots.
A crow's nest is usually a substantial structure made of sticks and twigs and open at the top. It is usually placed in a tall tree. Crows generally lay three to five mottled green eggs, but they may lay as many as eight at one time. Although both parents construct the nest, the female alone incubates the eggs. Both parents assist in the care of the newly hatched young.
There are numerous species known as crows. Together with ravens and jays, they make up the crow family, Corvidae, in the order Passeriformes.