American Crow
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2008-06-07T02:23:01Z
QVanillaQ
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/* Taxonomy and systematics */ title spacing
{{Taxobox
| name = American Crow
| image = Corvus-brachyrhynchos-001.jpg
| image_width = 240px
| status = LC
| status_system = iucn3.1
| regnum = [[Animalia]]
| phylum = [[Chordata]]
| classis = [[Aves]]
| subclassis = [[Neornithes]]
| infraclassis = [[Neognathae]]
| superordo = [[Neoaves]]
| ordo = [[Passeriformes]]
| subordo = [[Passeri]]
| superfamilia = [[Corvoidea]]
| familia = [[Corvidae]]
| genus = ''[[crow|Corvus]]''
| species = '''''C. brachyrhynchos'''''
| binomial = ''Corvus brachyrhynchos''
| binomial_authority = [[Christian Ludwig Brehm|Brehm]], 1822
| range_map = Corvus_brachyrhynchos_distribution.png
| range_map_width = 240px
| range_map_caption = Global range
}}
The '''American Crow''', ''Corvus brachyrhynchos'', is a large [[passerine]] bird [[species]] of the [[family (biology)|family]] [[Corvidae]]. It is a common bird found throughout much of [[North America]]. In the interior of the continent south of the [[Arctic]], it is simply '''"the crow"''' as no other such birds occur there on any regular basis.
It is one of several species of corvid which are entirely black in color, though it can be distinguished from the other two (but see also [[#Taxonomy and systematics|below]]) such birds in its range - from the [[Common Raven]] (''C. corax'') by size and behavior, and on the [[East Coast of the United States]] from the [[Fish Crow]] (''C. ossifragus'') by call.
American Crows are common, widespread and adaptable, but they are highly susceptible to the [[West Nile Virus]]. They are monitored as an [[indicator species]]. Direct transmission of the virus from American Crows to humans is not recorded to date and in any case not considered likely.
==Description==
[[Image:Corvus brachyrhynchos 30157.JPG|thumb|left|200px|"''Caah-caah-caah''"]]
{{Sound sample box align left|Sound sample:}}{{Listen|filename=Corvus brachyrhynchos call.ogg|title=American Crow calls|format=[[Ogg]]}}{{sample box end}}
The American Crow is a distinctive bird with [[iridescence|iridescent]] black feathers all over. Its legs, feet and bill are also black. They are 16-20 inches (about 40-50 cm) in length, of which the tail makes up about 40%. Each wing is around 7-8 in (27-34 cm) long. The bill length is on average 2 in (5 cm), varying strongly according to location.<ref name = m&b1994>Madge & Burn (1994)</ref>
The most usual call is a loud, short, and rapid ''caah-caah-caah''. Usually, the birds thrust their heads up and down as they utter this call. American Crows can also produce a wide variety of sounds and sometimes mimic noises made by other animals, including other birds.
Visual differentiation from the [[Fish Crow]] (''C. ossifragus'') is extremely difficult and often inaccurate. Nonetheless, differences apart from size do exist. Fish Crows tend to have more slender bills and feet. There may also be a small sharp hook at the end of the upper bill. Fish Crows also appear as if they have shorter legs when walking. More dramatically, when calling, Fish Crows tend to hunch and fluff their throat feathers.
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, their larger-looking heads and of course their strongly solitary habits. They also fluff their throat feathers when calling like Fish Crows, only more so.<ref>BirdWeb (2005)</ref>
==Taxonomy and systematics==
The American Crow was described by [[Christian Ludwig Brehm]] in 1822{{Fact|date=February 2008}}. Its [[scientific name]] means literally "short-billed crow", from [[Ancient Greek]] ''brachy-'' (βραχυ-) "short-" and ''rhynchos'' (ρυνχος) "bill".<ref>Liddell ''et al.'' (1980)</ref>
The [[Northwestern Crow]] (''C. caurinus'') is very closely related to the American Crow. Its ancestors became separated by [[Ice Age]] glaciation west of the [[Rocky Mountains]]. It is by and large [[endemism|endemic]] to [[Pacific temperate rain forests]] where it all but replaces the American Crow. Only in the [[Seattle]] region they co-coccur to any extent. In [[habitus]], they are still much alike to each other from one another where their ranges overlap. The voice however represents a distinct difference between the two species.<ref>Dick (2007)</ref>
Four subspecies are recognized. They differ in bill proportion and form a rough NE-SW [[cline (population genetics)|clinal]] in size across [[North America]]. Birds are smallest in the far west and on the south coast.<ref name = m&b1994 />
*''Corvus brachyrhynchos brachyrhynchos'': Northeastern [[USA]], eastern [[Canada]] and surroundings. Largest subspecies.
*''Corvus brachyrhynchos hesperis'' – '''Western Crow''': Western North America except [[arctic]] north, [[Pacific Northwest]] and extreme south. Smaller overall with a proportionally more slender bill<ref name = g&g87>Goodwin & Gillmor (1976): p.87</ref> and low-pitched voice.
*''Corvus brachyrhynchos pascuus'' – '''Florida Crow''': [[Florida]]. Mid-sized, short-winged but decidedly long bill and legs.<ref name = g&g87 />
*''Corvus brachyrhynchos paulus'': Southern USA. Smaller overall, bill also small.<ref>Goodwin & Gillmor (1976): p.88</ref>
==Ecology==
The range of the American Crow extends from the [[Pacific Ocean]] to the [[Atlantic Ocean]] in [[Canada]], on the [[France|French]] islands of [[Saint-Pierre and Miquelon]], south through the [[United States]], and into northern [[Mexico]].<ref name = redlist>BLI (2004)</ref> Virtually all types of country from wilderness, farmland, parks, open woodland to towns and major cities are inhabited; it is absent only from [[Pacific temperate rain forests]] and [[tundra]] habitat. This crow is a permanent resident in most of the USA, but most Canadian birds [[bird migration|migrate]] some distances southward in winter. Outside of the nesting season, these birds often gather in large communal roosts at night.
Most wild American Crows live for about 7-8 years. Captive birds are known to have lived up to 30 years.<ref name = cdep2001>CDEP (2001)</ref>
===Food and feeding===
The American Crow is [[omnivore|omnivorous]]. It will feed on invertebrates of all types, [[carrion]], scraps of human food, seeds, eggs and nestlings, stranded fish on the shore and various grains. American Crows are active hunters and will prey on [[mouse|mice]], [[frog]]s, and other small animals. In winter and autumn, the diet of American Crows is more dependent on nuts and acorns. Occasionally, they will visit [[bird feeder]]s.<ref name = parr2005>Parr (2005)</ref> The American Crow is one of only a few species of bird that has been observed modifying and using tools to obtain food.<ref>Caffrey (2000)</ref>
Like most crows, they will scavenge at rubbish dumps, scattering garbage in the process. Where available, [[maize|corn]], [[wheat]] and other crops are a favorite food. These habits have historically caused the American Crow to be considered a nuisance. However, it is suspected that the harm to crops is offset by the service the American Crow provides by eating insect pests.<ref name = parr2005 />
[[Image:Crowoutline.jpg|thumb|right|outline of crow.]]
===Nesting===
American Crows are [[monogamous]] [[cooperative breeding]] birds. Mated pairs form large families of up to 15 individuals from several breeding seasons that remain together for many years.<ref name = segelken>Roger Segelken: [http://www.news.cornell.edu/chronicle/97/4.10.97/crow.html Tree-climbing researcher knows exactly how far the crow flies] ''Cornell Chronicle''. Retrieved 2006-OCT-25,</ref> Offspring from a previous nesting season will usually remain with the family to [[helpers at the nest|assist in rearing]] new nestlings. American Crows do not reach breeding age for at least two years.<ref>CLO (2002), SAS (2005)</ref> Most do not leave the nest to breed for four to five years.<ref name = segelken />
The nesting season starts early, with some birds incubating eggs by early April already.<ref>Henninger (1906)</ref> American Crows build bulky stick nests, nearly always in trees but sometimes also in large bushes and, very rarely, on the ground. They will nest in a wide variety of trees, including large conifers, although oaks are most often used. Three to six eggs are laid and [[incubate (bird)|incubated]] for 18 days. The young are usually [[fledge]]d by about 35 days after hatching.
===West Nile Virus===
American Crows succumb easily to [[West Nile virus]] infection. This was originally a [[mosquito]]-borne [[Africa]]n 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. It is estimated that the American Crow population has dropped by 45% since 1999{{Fact|date=February 2008}}<!-- A. Marm Kilpatrick et al, Nature journal, around May 17, 2007 -->; the disease runs most rampant in the [[subtropical]] conditions which encourage reproduction of its mosquito [[vector (biology)|vector]]s 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.<ref>CLO (2002), Caffrey ''et al.'' 2005)</ref> Because of this, American Crows are a [[sentinel species]] indicating the presence of West Nile virus in an area. Crows cannot transmit the virus to humans directly.<ref name = cdep2001 />
===Status and conservation===
American Crows are protected internationally by the [[Migratory Bird Treaty Act of 1918]]. Despite attempts by humans in some areas to drive away or eliminate these birds, they remain widespread and very common. The number of individual American Crows is estimated by [[Birdlife International]] to be around 31,000,000. The large population, as well as its vast range, are the reasons why the American Crow is considered to be of [[least concern]], meaning that the species is not threatened.<ref name = redlist />
==In popular culture==
The abundance of the American Crow in both rural and urban environments have made them very familiar to all Americans. They are the [[archetype|archetypal]] "crow" of North America and have found their way to vernacular speech and popular culture.
* "[[Eating crow]]" means suffering embarrassment after having previously boasted. This phrase originates in the use of crows - including this species - as [[famine food]] (compare "[[humble pie]]"). While American Crows are theoretically edible they have little meat; in addition, namely those from densely-settled areas often carry [[parasite]]s that [[dead-end host|can infect humans]].
* In the early 20th century, "crow" was common as a racial slur for [[African-American]]s. For example, the [[White American]] [[vaudeville]] act [[Moran and Mack]] had a performance called "Two Black Crows" which was popular in the 1920s, where they played two stereotyped "crows" speaking in exaggerated [[African American Vernacular English|Black American accents]].
* "[[Jim Crow]]" was originally the name of a 19th-century [[minstrel]] character. It became a collective term for [[blackface]] performances of that era, as well as laws - particularly in the [[American South]] - that [[racial segregation|segregated]] blacks.
==Footnotes==
{{Reflist}}
==References==
* {{IUCN2006|assessors={{aut|BirdLife International (BLI)}}|year=2004|id=51158|title=Corvus brachyrhynchos|downloaded=26 October 2006}} Database entry includes justification for why this species is of least concern
* {{aut|Caffrey, Carolee}} (2000): Tool Modification and Use by an American Crow]. ''[[Wilson Bulletin|Wilson Bull.]]'' '''112'''(2): 283–284. <small>[[Digital Object Identifier|DOI]]:10.1676/0043-5643(2000)112[0283:TMAUBA]2.0.CO;2</small> [http://www.bioone.org/perlserv/?request=get-abstract&doi=10.1676%2F0043-5643%282000%29112%5B0283%3ATMAUBA%5D2.0.CO%3B2 HTML abstract]
* {{aut|Caffrey, Carolee; Smith, Shauna C.R. & Weston, Tiffany J.}} (2005): West Nile Virus Devastates an American Crow Population. ''[[Condor (journal)|Condor]]'' '''107'''(1): 128-132. <small>{{doi|10.1650/7646}}</small> (HTML abstract)
* {{aut|[[Cornell Lab of Ornithology]] (CLO)}} (2002): Bird Guide - [http://www.birds.cornell.edu/AllAboutBirds/BirdGuide/American_Crow_dtl.html American Crow]. Retrieved 2006-OCT-24.
* {{aut|Connecticut Department of Environmental Protection (CDEP)}} (2001): [http://www.mosquito.state.ct.us/fact/crowfact.htm American Crow Fact Sheet]. Version of 2001. Retrieved 2006-OCT-25.
* {{aut|Dick, Gary Owen}} (2007): Whatbird.com Field Guide to Birds of North America - Retrieved 2007-OCT-18.
* {{aut|Goodwin, Derek & Gillmor, Robert}} (1976): ''Crows of the World'' (1st ed.). University of Washington Press, Seattle.
* {{aut|Henninger, W.F.}} (1906): A preliminary list of the birds of Seneca County, Ohio. ''[[Wilson Bulletin|Wilson Bull.]]'' '''18'''(2): 47-60. [http://elibrary.unm.edu/sora/Wilson/DJVU/v018n02/P0047-P0060.djvu DjVu fulltext] [http://elibrary.unm.edu/sora/Wilson/v018n02/p0047-p0060.pdf PDF fulltext]
* {{aut|[[Henry Liddell|Liddell, Henry George]]; [[Robert Scott (philologist)|Scott, Robert]]; [[Henry Stuart-Jones|Stuart-Jones, Henry]] & McKenzie, Roderick}}: (1980): ''[[A Greek-English Lexicon]]'' (abridged ed.). Oxford University Press, Oxford, UK. <small>ISBN 0-19-910207-4</small>
* {{aut|Madge, Steve & Burn, Hilary}} (1994): ''Crows and jays: a guide to the crows, jays and magpies of the world''. A&C Black, London. <small>ISBN 0-7136-3999-7</small>
* {{aut|Parr, C.}} (2005): [[Animal Diversity Web]] - [http://animaldiversity.ummz.umich.edu/site/accounts/information/Cyanocitta_cristata.html ''Corvus brachyrhynchos'']. Retrieved 2007-OCT-24.<!-- there is some more information here e.g. on predators and status -->
* {{aut|Seattle [[Audubon Society]] (SAS)}}: BirdWeb - [http://www.birdweb.org/birdweb/bird_details.aspx?id=316 American Crow]. Retrieved 2006-OCT-24.
==External links==
{{commons|Corvus brachyrhynchos}}
===Images===
* [http://depts.washington.edu/natmap/facts/american_crow_712.html American Crow Facts and Photos]
* [http://www.skullsite.com/images/dbimages/large/corvusbrachyrhynchos_s.jpg Skull of American Crow]
===Video===
* [http://ibc.hbw.com/ibc/phtml/especie.phtml?idEspecie=8286 American Crow videos] on the Internet Bird Collection
===Audio===
* [http://www.shades-of-night.com/aviary/sounds/crow2.wav American Crow call]
[[Category:Birds of North America]]
[[Category:Fauna of Delaware and Maryland|Crow, American]]
[[Category:Corvus]]
[[Category:Crows]]
[[Category:Tool-using species]]
[[de:Amerikanerkrähe]]
[[es:Corvus brachyrhynchos]]
[[fr:Corneille d'Amérique]]
[[it:Corvus brachyrhynchos]]
[[ja:アメリカガラス]]
[[pl:Wrona amerykańska]]
[[pt:Corvo-americano]]
[[ru:Американская ворона]]
[[fi:Amerikanvaris]]