American crow (Corvus brachyrynchos)

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American crow perched on branch
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American crow fact file

American crow description

KingdomAnimalia
PhylumChordata
ClassAves
OrderPasseriformes
FamilyCorvidae
GenusCorvus (1)

The American crow (Corvus brachyrynchos) is a relatively large, thick-necked, uniformly black bird with a purple iridescence on the back and wings (2) (3) (4) (5). Both sexes are similar, although the female is slightly smaller than the male (2) (3) (5) and has large brood patch during the breeding season (3).

Both the male and female American crow have a heavy, straight black bill, black feet and legs, and brown eyes (2) (4) (5), and the nasal openings are covered by prominent, stiff, bristle-like feathers (3) (5). The short tail of the American crow is rounded or squared at the tip (3) (4), and in flight, the long, finger-like flight feathers are visible at the tips of the broad wings (4) (5).

The juvenile American crow is similar in appearance to the adult, although the black plumage is dull rather than glossy, the feathers are fluffier and looser, and the tail feathers are narrower and more pointed (2) (3) (5). The feathers of the back, wings and tail are often slightly brown, contrasting with the rest of the body (2) (3), and the eyes are grey-blue, changing to brown as the juvenile matures (2) (3) (5). The inside of the mouth is bright red for the first year, later becoming black (5). Nestlings of the American crow are almost bald, with a light covering of down feathers (3).

The American crow has a wide range of vocalisations, some of which are the mimicked sounds of other species (2). A short, hoarse ‘ahhh’ is commonly made, which can vary in pitch, emphasis and pattern (2) (5). Vocalisations may differ between populations, with some having individual ‘dialects’ (2).

Three subspecies of American crow are generally recognised; Corvus brachyrynchos brachyrynchos, Corvus brachyrynchos hesperis and Corvus brachyrynchos pascuus, with some also recognising a fourth, Corvus brachyrynchos paulus. They vary in range, size, vocalisation patterns and behaviour (2) (3) (5). C.b.brachyrynchos is the largest of the three generally recognised subspecies and C.b.hesperis is the smallest (2). C.b.hesperis has a low-pitched voice and a weak bill, which is small and straight (5). C.b.pascuus has a long bill, long legs and large feet (2) (3) (5), and also has a greater variety of vocalisations than the other two subspecies. This subspecies also differs in not forming flocks (3)

Size
Length: 43 - 53 cm (2) (3)
Wingspan: 85 - 100 cm (4)
Weight
316 - 575 g (3)
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American crow biology

The diet of the American crow consists mostly of invertebrates such as earthworms, grasshoppers, moth and butterfly larvae, beetles, and marine invertebrates (2) (3). An opportunistic feeder (3), the American crow also eats plant matter such as seeds, fruits and crops, as well as amphibians, reptiles, small birds and mammals, carrion, fish, crabs and gastropods (2) (3) (5). Its existence in inner city areas leads this species to also eat discarded human food (3), which it will occasionally harass people for (2).

The American crow mostly forages on the ground (3), although it also feeds along the edges of water bodies and in shallow water, using its bill to pick, probe, grab or dig for food (2) (3). When chasing prey or moving quickly on the ground, the American crow moves by hopping, with one foot hitting the ground slightly before the other (3). The American crow is known to drop certain types of prey out of the air onto a hard surface to crack their thick shells (2) (3). Excess food may be buried in a hole in the ground and retrieved at a later date (2) (3) (5).

A gregarious species, the American crow usually occurs in pairs or family groups and can form enormous flocks outside of the breeding season (2) (4) (5), with some winter roosts averaging around 200,000 birds (5). Large flocks of between 30 and 200 individuals, occasionally up to 1,000, are formed in the northern areas of the range for the southward migration between August and December. The return northern migration to the breeding grounds usually occurs between February and April (2) (3) (5).

The American crow is usually monogamous (2). The nest is built by both sexes between February and early June, and is usually well hidden in the high horizontal branches of a tree, typically close to the trunk. However, nests can sometimes also be found in bushes, buildings or telegraph poles (2) (3) (5). A new nest is built each year (3), and is composed of an outer layer of twigs, stuffed internally with bark, grass, stalks, animal hair, mud, roots, leaves and occasionally refuse (2) (3) (5). The nest of the American crow is usually solitary, although colonies are occasionally formed by some populations (5). Breeding pairs are occasionally known to allow one or more non-breeding individuals to live with them as ‘helpers’, to help defend the nest from predators and feed the young (2) (5).

The female American crow lays a clutch of four or five eggs between February and June, which are blue-green or pale olive, speckled brown and grey and are smooth and slightly glossy (3) (5). The female then incubates the eggs for between 16 and 18 days (2) (5), with the male and any ‘helpers’ bringing food to the nest (2) (3). When the eggs have hatched, the female also begins to forage for food (3) (5). Most fledging occurs between May and July (2), after which the young follow the male and female while they are foraging and learn how to catch prey (3). Some young remain within the territory of the breeding pair to act as ‘helpers’ in future breeding seasons, whereas others travel to join other flocks. Occasionally, the young American crows leave the natal territory but return in the following breeding season to assist the adults (2).

The American crow is known to live for up to 14 years in the wild and up to 59 years in captivity (2).

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American crow range

The range of the American crow extends south from Canada to northern Mexico (6), with each subspecies residing in a different area (3) (5). C.b.brachyrynchos is found from the southwest Northwest Territories in Canada, east to Newfoundland and south throughout the eastern and western United States to the Gulf of Mexico. C.b.hesperis is found in southwest Canada, the western U.S. and northwest Mexico, and C.b.pascuus is found in Florida in the U.S. (2).

Northern populations of the American crow migrate south in winter, although southern populations are mostly sedentary (3) (5). The different subspecies of the American crow are known to join at common wintering grounds after the southward migration (3) (5).

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American crow habitat

The habitat of the American crow is highly variable (3), including both natural and man-made areas, such as farmland, pastures, refuse dumps, ranches, parks and golf courses, as well as forest edges and open woodlands (2) (3). It is also found in large cities, where it is known to nest on buildings (2).

The American crow prefers relatively open areas, which allow access for feeding, but which also have scattered trees for roosting and nesting (3). This species avoids dry or heavily forested areas (5).

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American crow status

The American Crow is classified as Least Concern (LC) on the IUCN Red List (1)

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American crow threats

The American crow has been persecuted by humans due to the damage it can do to agriculture, its predation on gamebird nests, the potential spread of disease, and due to it being seen as a nuisance in areas where it is known to beg for food and rummage through waste (2). Dynamiting popular roosting sites was previously used to manage large populations, although this is no longer allowed (3).

A common and widespread species, the American crow is not currently thought to be under threat of extinction, although it is highly susceptible to diseases such as West Nile Virus and rabies (2) (3). Overall, the population of this opportunistic species is thought to be increasing (3) (6).

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American crow conservation

The American crow is protected in the United States by the Migratory Bird Treaty Act, although hunting is still allowed. In Canada, this species is largely unprotected, but there are restrictions in certain areas which prevent any hunting during the nesting season (3). There are not known to be any other specific conservation measures in place for this common and widespread crow.

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Find out more

Find out more about the American crow and its conservation:

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Authentication

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

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Glossary

Brood patch
An area of featherless skin on the underside of a bird during the nesting season. Well supplied with blood vessels, this patch of skin aids in the transfer of heat to the eggs.
Carrion
The flesh of a dead animal.
Flight feathers
The feathers at the end of the wing, involved in flight.
Gastropods
A group of molluscs that have a well-defined head, an unsegmented body and a broad, flat foot. They can possess a single, usually coiled shell or no shell at all. Includes slugs, snails and limpets.
Incubate
To keep eggs warm so that development is possible.
Invertebrates
Animals with no backbone, such as insects, crustaceans, worms, molluscs, spiders, cnidarians (jellyfish, corals, sea anemones) and echinoderms.
Larva
Immature stage in an animal’s lifecycle, after it hatches from an egg and before it changes into the adult form. Larvae are typically very different in appearance to adults; they are able to feed and move around but are usually unable to reproduce.
Monogamous
Having only one mate during a breeding season, or throughout the breeding life of a pair.
Natal
Of or relating to birth.
Subspecies
A population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.
Territory
An area occupied and defended by an animal, a pair of animals or a group.
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References

  1. IUCN Red List (March, 2012)
    http://www.iucnredlist.org/
  2. del Hoyo, J., Elliott, A. and Christie, D. (2009) Handbook of the Birds of the World. Volume 14: Bush-Shrikes to Old World Sparrows. Lynx Edicions, Barcelona.
  3. Verbeek, N.A. and Caffrey, C. (2002) American crow (Corvus brachyrynchos). In: Poole, A. (Ed.) The Birds of North America Online. Cornell Lab of Ornithology, Ithaca. Available at: 
    http://bna.birds.cornell.edu/bna/species/647/articles/introduction
  4. The Cornell Lab of Ornithology: All About Birds - American crow (March, 2012)
    http://www.allaboutbirds.org/guide/American_Crow/id/ac
  5. Madge, S. and Burn, H. (1994) Crows and Jays: A Guide to the Crows, Jays and Magpies of the World. Christopher Helm, London.
  6. BirdLife International (March, 2012)
    http://www.birdlife.org/datazone/speciesfactsheet.php?id=5775
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Image credit

American crow perched on branch  
American crow perched on branch

© Jim Zipp / www.ardea.com

Ardea wildlife pets environment
59 Tranquil Vale
London
SE3 0BS
United Kingdom
Tel: +44 (0) 208 318 1401
ardea@ardea.co.uk
http://www.ardea.com

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