The American crow (Corvus brachyrhynchos) is a large passerine bird species of the family Corvidae.
[3] Its scientific name means literally 'short-billed crow', from Ancient Greek βραχυ- brachy- ('short-') and ρυνχος rhynchos ('billed').
Subspecies differ in bill proportion and form a rough NE–SW clinal in size across North America.
American crows can also produce a wide variety of sounds and sometimes mimic noises made by other animals, including other birds, such as barred owls.
[17] If seen flying at a distance from where size estimates are unreliable, the distinctly larger common ravens (C. corax) can be distinguished by their almost lozenge-shaped tail and their larger-looking heads.
Ravens also soar for extended periods, unlike crows, which rarely fly more than a few seconds without flapping their wings.
[24][25][26] Virtually all types of country from wilderness, farmland, parks, open woodland to towns and major cities are inhabited; it is absent only from tundra habitat, where it is replaced by the common raven.
Thus much of their behavior, including daily routine, migration, molting, survivorship, age of first breeding, nestling development, and the nature of nesting helpers, remains poorly studied.
[30] It will feed on invertebrates of all types, carrion, scraps of human food, fruits,[31] nuts such as walnuts and almonds, seeds, eggs and nestlings, stranded fish on the shore and various grains.
American crows are active hunters and will prey on mice, young rabbits,[31] frogs, and other small animals.
Mated pairs form large families of up to 15 individuals from several breeding seasons that remain together for many years.
[36] American crows build bulky stick nests, nearly always in trees but sometimes also in large bushes and, very rarely, on the ground.
Predation primarily occurs at the nest site and eggs and nestlings are frequently eaten by snakes, raccoons, ravens and domestic cats.
Adults are less frequently predated, but face potential attack from great horned owls, red-tailed hawks, peregrine falcons and eagles.
This was originally a mosquito-borne African virus causing encephalitis in humans and livestock since about 1000 AD, and was accidentally introduced to North America in 1999, apparently by an infected air traveller who got bitten by a mosquito after arrival.
[40] The disease runs most rampant in the subtropical conditions which encourage reproduction of its mosquito vectors among which Culex tarsalis is most significant.
Mortality rates appear to be higher than those in other birds, causing local population losses of up to 72% in a single season.
[42] Crows are used as a motif in some human cultures, often associated with death, thieves, graveyards, bad luck, and other negative connotations.
The large population and vast range result in the least concern status for the American crow, meaning that the species is not threatened with extinction.
[1] Crows have been killed in large numbers by humans, both for recreation and as part of organized campaigns of extermination.
In the first half of the 20th century, state-sponsored campaigns dynamited roosting areas, taking large numbers of crows.
The effect on populations was negligible and damage to agricultural crops did not decrease, and thus the campaign was halted due to its ineffectiveness.
In a study taking data from 1917 to 1999, intentional killings were the overwhelming cause of death for crows, accounting for 68% of all recovered bird bands.