Corvus is a widely distributed genus of birds in the family Corvidae. Ranging in size from the relatively small pigeon-size jackdaws (Eurasian and Daurian) to the common raven of the Holarctic region and thick-billed raven of the highlands of Ethiopia, the 40 or so members of this genus occur on all temperate continents except South America, and several islands. In Europe, the word "crow" is used to refer to the carrion crow or the hooded crow, while in North America it is used for the American crow or the northwestern crow.
The crow genus makes up a third of the species in the Corvidae family. 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 approaching that of some apes.
In medieval times, the crow was thought to live an abnormally long life. They were also thought to be monogamous throughout their long lives. It was thought that the crow could predict the future, in that it was thought to predict rain and reveal ambushes. Crows were also thought to lead flocks of storks while they crossed the sea to Asia.
North American urban crow history
Crows are found in major cities across the world, and there has been a major increase in the number of crows in urban settings since the 1900s. Historical records suggest that the population of American crows found in North America has been growing steadily since the introduction of European colonization, and spread east to west with the opening of the frontier. Crows were uncommon in the Pacific Northwest in the 1900s, except in riparian habitats. Populations in the west increased substantially from the late 1800s to mid 1900s. Crows spread along with agriculture and urbanization into the western part of North America.
