Corvus (genus)
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219803801
2008-06-16T23:06:49Z
82.203.170.158
disambiguate Rook
{{Mergefrom|Raven|date=February 2008}}{{Mergefrom|Crow|date=February 2008}}
{{Refimprove|date=July 2007}}
{{Taxobox
| name = Corvus
| image = Corvus_corax_(FWS).jpg
| image_width = 260px
| image_caption = Common Raven (''[[Corvus corax]]'')
| regnum = [[Animal]]ia
| phylum = [[Chordate|Chordata]]
| classis = [[Bird|Aves]]
| ordo = [[Passerine|Passeriformes]]
| familia = [[Corvidae]]
| genus = ''''' Corvus '''''
| genus_authority = [[Carolus Linnaeus|Linnaeus]], [[1758]]
| subdivision_ranks = Species
| subdivision =
See text
}}
The [[genus]] '''''Corvus''''' consists of large [[Passerine]] birds. They are either black all over, or mainly black with white or grey patches. They range in size from the relatively small [[jackdaw]]s (still larger than most other passerines) to the very large [[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 [[continent]]s except [[South America]] and [[Antarctica]], and on many offshore and oceanic islands.
Members of the group as a whole are known as "True Crows"<ref>[http://www.avianweb.com/crows.html Crows<!-- Bot generated title -->]</ref>. Most species are known as "crows", others as "jackdaws", "raven" or "rook"; some of these names reflect relationships within the [[genus]], while others do not.
==Systematics==
The genus was originally described by [[Carolus Linnaeus|Linnaeus]] in his 18th century work ''[[Systema Naturae]]''.<ref>{{la icon}} {{cite book | last=Linnaeus | first=C | authorlink=Carolus Linnaeus | title=Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata. | publisher=Holmiae. (Laurentii Salvii). | date=1758| pages=824 | url=http://dz1.gdz-cms.de/index.php?id=img&no_cache=1&IDDOC=265100}}</ref> The name is from the [[Latin (language)|Latin]] ''corvus'' meaning "raven".<ref>{{cite book | last = Simpson | first = D.P. | title = Cassell's Latin Dictionary | publisher = Cassell Ltd. | date= 1979 | edition = 5 | location = London | pages = 883 | url = | doi = | id = ISBN 0-304-52257-0}}</ref>
The [[type species]] is the [[Common Raven]] ''(Corvus corax)''; others named in the same work include the [[Carrion Crow]] ''(C. corone)'', the [[Hooded Crow]] ''(C. cornix)'', the [[Rook (bird)|Rook]] ''(C. frugilegus)'', and the [[Jackdaw]] ''(C. monedula)''. The genus was originally broader, as the [[Magpie]] was designated ''C. pica'' before later being moved into a genus of its own. There are now considered to be at least 42 [[extant]] species in this genus, and at least 14 [[extinct]] species have been described.
There is no good systematic approach to subdividing the genus at present{{Fact|date=March 2008}}<!-- Jackdaws and Rook at least seem clear enough... -->. Generally, it is assumed that species from a geographical area are more closely related to each other than to other lineages, but this is not necessarily correct. For example, while the [[Carrion Crow|Carrion]]/[[Collared Crow|Collared]]/[[House Crow]] complex is certainly closely related to each other, the situation is not at all clear regarding the [[Australia]]n/[[Melanesia]]n species. Furthermore, as many species are similar in appearance, determining actual range and characteristics can be very difficult, such as in Australia where the five (possibly six) species are almost identical in appearance.
The [[fossil record]] of crows is rather dense in Europe, but the relationships among most prehistoric species is not clear. Jackdaw-, crow- and raven-sized forms seem to have existed since long ago and crows were regularly hunted by humans up to the [[Iron Age]]{{Fact|date=March 2008}}, documenting the evolution of the modern taxa. American crows are not as well documented.{{Fact|date=March 2008}} They appear to have [[evolve]]d in central [[Asia]] and radiated out into [[North America]], [[Africa]], [[Europe]], and [[Australia]]{{Fact|date=March 2008}}.
The latest evidence<ref>[http://www.pnas.org/cgi/content/abstract/0401892101v1 Phylogeny and diversification of the largest avian radiation - Barker et al., 10.1073/pnas.0401892101 - Proceedings of the National Academy of Sciences<!-- Bot generated title -->]</ref> appears to point towards an Australasian origin for the early family (Corvidae) though the branch that would produce the modern groups such as [[jays]], [[magpies]] and large predominantly black ''Corvus''. Crows had left Australasia and were now developing in [[Asia]]. ''Corvus'' has since re-entered Australia (relatively recently) and produced five species with one recognized sub-species.
A surprisingly high number of species have become [[extinct]] after human colonization; the loss of one prehistoric Caribbean crow could also have been related to the [[last ice age]]'s climate changes.{{Fact|date=March 2008}}
===List of Species in the genus Corvus===
[[Image:House Crows (Corvus splendens) grooming in Kolkata I IMG 4324.jpg|thumb|250px|right|[[House crow|House Crows]] (''Corvus splendens'') grooming each other in [[Kolkata]], [[India]]]]
'''Australian and Melanesian species'''
*[[Australian Raven]] ''C. coronoides''
*[[Forest Raven]] ''C. tasmanicus''
**Relict Raven ''C. (t.) boreus''
*[[Little Crow (bird)|Little Crow]] ''C. bennetti''
*[[Little Raven]] ''C. mellori''
*[[Torresian Crow]] ''C. orru''
*[[New Caledonian Crow]] ''C. moneduloides''
*[[Long-billed Crow]] ''C. validus''
*[[White-billed Crow]] ''C. woodfordi''
*[[Bougainville Crow]] ''C. meeki''
*[[Brown-headed Crow]] ''C. fuscicapillus''
*[[Grey Crow]] ''C. tristis''
*[[New Ireland Crow]], ''Corvus'' sp. ([[Late Quaternary prehistoric birds|prehistoric]])
'''New Zealand species'''
* [[Chatham Islands Raven]], ''C. moriorum'' ([[Late Quaternary prehistoric birds|prehistoric]])
* [[New Zealand Raven]], ''C. antipodum'' ([[Late Quaternary prehistoric birds|prehistoric]])
'''Pacific island species'''[[Image:Pied crow.jpg|thumb|250px|right|A [[Pied Crow]] (''Corvus albus'') in flight]]
*[[Mariana Crow]], ''C. kubaryi''
*[[Hawaiian Crow]] or '''‘Alala''' ''C. hawaiiensis'' ([[extinct in the wild]], formerly ''C. tropicus'')
*[[High-billed Crow]], ''C. impluviatus'' ([[Late Quaternary prehistoric birds|prehistoric]])
*Robust Crow, ''C. viriosus'' ([[Late Quaternary prehistoric birds|prehistoric]])
'''Tropical Asian species'''
*[[Slender-billed Crow]] ''C. enca''
*[[Piping Crow]] ''C. typicus''
*[[Banggai Crow]] ''C. unicolor'' (possibly [[extinct]])
*[[Flores Crow]] ''C. florensis''
*[[Collared Crow]] ''C. torquatus''
*[[Daurian Jackdaw]] ''C. dauricus''
*[[House Crow]] ''C. splendens''
*[[Large-billed Crow]] ''C. macrorhynchos''
**[[Jungle Crow]] ''C. (m.) levaillantii''
'''Eurasian and North African species'''[[Image:Dartmoorrook.JPG|thumb|250px|right|A [[Rook (bird)|Rook]] (''Corvus frugilegus'') at [[Dartmoor]], [[England]]]]
*[[Brown-necked Raven]] ''C. ruficollis''
*[[Somali Crow]] or Dwarf Raven ''C. edithae''
*[[Fan-tailed Raven]] ''C. rhipidurus''
*[[Jackdaw]] ''C. monedula''
*[[Rook (bird)|Rook]] ''C. frugilegus''
*[[Hooded Crow]] ''C. cornix''
**Mesopotamian Crow, ''C. (c.) capellanus''
*[[Carrion Crow]] ''C. corone''
**Carrion Crow (Eastern subspecies) ''C. (c.) orientalis''
*''Corvus larteti'' ([[fossil]]: Late Miocene of France, or C Europe?)<!-- PaleontogrItal89:3 -->
*''Corvus pliocaenus'' ([[fossil]]: Late Pliocene –? Early Pleistocene of SW Europe)<!-- Ardeola51:91 Boreas32:521 -->
*''Corvus antecorax'' ([[fossil]]: Late Pliocene/Early – Late Pleistocene of Europe; may be subspecies of ''[[Corvus corax]]''<!-- Ardeola51:91; Boreas32:521; ColoqPaleontol1:345 RevPortArqueol5:29 -->
*''Corvus betfianus'' ([[fossil]])
*''Corvus praecorax'' ([[fossil]])
*''Corvus simionescui'' ([[fossil]])
*''Corvus fossilis'' ([[fossil]])[[Image:Crows In England.jpg|thumb|250px|right|[[Common raven|Common Ravens]] (''Corvus corax'') at the [[Tower of London]]]]
*''Corvus moravicus'' ([[fossil]])
*''Corvus hungaricus'' ([[fossil]])
'''Holarctic species'''
*[[Common Raven]] ''C. corax'' (see also next section)
**[[Pied Raven]], ''C. c. varius'' morpha ''leucophaeus'' (an [[extinct]] color variant)
'''North and Central American species'''
*[[American Crow]] ''C. brachyrhynchos''
*[[Western Raven]] ''C. (corax) sinuatus''
*[[Chihuahuan Raven]] ''C. cryptoleucus''
*[[Fish Crow]] ''C. ossifragus''
*[[Northwestern Crow]] ''C. caurinus''
*[[Tamaulipas Crow]] ''C. imparatus''
*[[Sinaloan Crow]] ''C. sinaloae''
*[[Jamaican Crow]] ''C. jamaicensis''
*[[White-necked Crow]] ''C. leucognaphalus''
*[[Palm Crow]] ''C. palmarum''
*[[Cuban Crow]] ''C. nasicus''[[Image:Thick-billed-Ravens.jpg|thumb|250px|right|[[Thick-billed Raven]]s ''Corvus crassirostris'' in eastern [[Africa]]]]
*Puerto Rican Crow ''C. pumilis'' ([[Late Quaternary prehistoric birds|prehistoric]]; possibly a subspecies of ''C. nasicus/palmarum'')
*''Corvus galushai'' ([[fossil]]: Big Sandy Late Miocene of Wickieup, USA)
*''Corvus neomexicanus'' ([[fossil]]: Late Pleistocene of Dry Cave, USA)<!-- Condor78:399 -->
'''Tropical African species'''
*[[Cape Crow]] ''C. capensis''
*[[Pied Crow]] ''C. albus''
*[[Somali Crow]] or '''Dwarf Raven''' ''C. edithae''
*[[Thick-billed Raven]] ''C. crassirostris''
*[[White-necked Raven]] ''C. albicollis''
In addition to the prehistoric forms listed above, some extinct [[chronospecies|chronosubspecies]] have been described. These are featured under the respective species accounts.
==Behavior==
===Calls===
<div style="float:right">{{Listen|filename=Corvus brachyrhynchos call.ogg|title=Corvus brachyrhynchos call|description=Call of Corvus brachyrhynchos ([[American Crow]])|format=[[Ogg/FLAC]]}}</div>
Crows make a wide variety of calls or vocalizations. Whether the crows' system of communication constitutes a [[language]] is a topic of debate and study. Crows have also been observed to respond to calls of other species; this behavior is presumably learned because it varies regionally. Crows' vocalizations are complex and poorly understood. Some of the many vocalizations that crows make are a "caw", usually echoed back and forth between birds, a series of "caws" in discrete units, counting out numbers, a long caw followed by a series of short caws (usually made when a bird takes off from a perch), an echo-like "eh-aw" sound, and more. These vocalizations vary by species, and within each species vary regionally. In many species, the pattern and number of the numerical vocalizations have been observed to change in response to events in the surroundings (i.e. arrival or departure of crows). Crows can hear sound frequencies lower than those that humans can hear, which complicates the study of their vocalizations.
===Intelligence===
[[Image:CrowWastebag.jpg|thumb|250px|right|[[Hooded Crow]] searching for food from a punctured garbage bag]]
True crows have long been viewed as very intelligent by humans (as seen in [[Aesop]]'s fable of [[The Crow and the Pitcher]]) and they often score very highly on animal intelligence tests, some [[species]] even top the [[avian IQ]] scale <ref>[http://news.bbc.co.uk/1/hi/sci/tech/4286965.stm BBC NEWS | Science/Nature | Crows and jays top bird IQ scale<!-- Bot generated title -->]</ref>. Crows in the northwestern U.S. Show modest linguistic capabilities and the ability to relay information over great distances, live in complex, hierarchic societies involving hundreds of individuals with various "occupations."{{Fact|date=March 2008}}
Many of the examples of intelligence involve the various use of tools that the True Crows readily use<ref>[http://www.sciencemag.org/cgi/content/abstract/306/5703/1903 The Mentality of Crows: Convergent Evolution of Intelligence in Corvids and Apes - Emery and Clayton 306 (5703): 1903 - Science<!-- Bot generated title -->]</ref>. For example, hooded crows in Israel have learned to use bread crumbs for [[fishing]] [[bait]].<ref>[http://www.orenhasson.com/EN/bait-fishing.htm Animal Intelligence - Birds' Mind: Bait-Fishing Crows<!-- Bot generated title -->]</ref>
Another species, the [[New Caledonian Crow]], has recently been intensively studied because of its ability to manufacture and use its own [[tool]]s in the day-to-day search for food, including dropping seeds into a heavy trafficked street and waiting for a car to crush them open<ref>http://en.wikipedia.org/wiki/The_Most_Extreme#Season_1</ref>. On [[October 5]], [[2007]], researchers from the [[University of Oxford]], [[England]] presented data acquired by mounting tiny video cameras on the tails of New Caledonian Crows. It turned out that they use a larger variety of tools than previously known, plucking, smoothing and bending twigs and grass stems to procure a variety of foodstuffs<ref>[http://dsc.discovery.com/news/2007/10/05/crows_ani.html?category=animals&guid=20071005130000&dcitc=w19-502-ak-0000 Discovery News Top Stories : Discovery Channel<!-- Bot generated title -->]</ref>.
Crow species in Australia are some of the few animals that have learned how to eat the toxic [[cane toad]]. A crow flips the toad over onto its back with its beak and then kills the toad by striking the thin underbelly skin with their beak. This thin skin lacks the [[poison]] [[glands]] that protect the toads from being eaten from above.<ref>[http://www.abc.net.au/news/stories/2007/09/15/2033759.htm Toads fall victim to crows in NT - ABC News (Australian Broadcasting Corporation)<!-- Bot generated title -->]</ref>
Additionally, it has been suggested that Common Ravens follow wolves or human hunters to kills, effectively using them as "tools," that provide meat. It has even been rumored that they might lead hunters to animals so that they might then eat the leftovers.<ref name="NBB297">[[#Reference-idHeinrich1991|Heinrich 1991]]</ref>
===Color and society===
{{Cleanup|date=March 2008}}
====Extra-specific uses of color in crow societies====
Many crow species are all black. Most of their natural enemies, the [[bird of prey|raptor]]s or "[[falconiformes]]", soar high above the trees, and hunt primarily on bright, sunny days when contrast between light and shadow is greatest.{{Fact|date=March 2008}} Crows take advantage of this by maneuvering themselves through the dappled shades of the trees, where their black color renders them effectively invisible to their enemies above{{Fact|date=March 2008}}, in order to set up complex ambush attacks{{Fact|date=March 2008}}. Fledglings are much duller than adults in appearances of great strategic importance to their societies{{Fact|date=March 2008}}. It is perhaps here where we find the greatest difference between ravens and crows; [[raven]]s tend to soar high in the air as raptors do.{{Fact|date=March 2008}}
While hawks tend to be the primary daytime predators of crows, their most deadly predators, in many areas, are the owls that hunt by night{{Fact|date=March 2008}}. Crows also will often mob owls much more fiercely when they find them in daylight than the hawks and other raptors{{Fact|date=March 2008}}. Frequently crows appear to "play" with hawks, taking turns "[[counting coup]]" while escorting the raptor out of their territory. Their attacks on owls, on the other hand, possess a definite serious quality.{{Fact|date=March 2008}}
====Intra-specific uses of color in crow societies====
Even in species characterized by being all black, one will still occasionally find variations, most of which appear to result from varying degrees of [[albinism]], such as:
* an otherwise all-black crow stunningly contrasted by a full set of brilliant, pure-white primary feathers.
* complete covering in varying shades of grey (generally tending toward the darker side).
* blue or red, rather than swarthy eyes (blue being more common than red).
* Some combination of the above
The treatment of these rare individuals may vary from group to group, even within the same species. For example, one such individual may receive special treatment, attention, or care from the others in its group{{Fact|date=March 2008}}, while another group of the same species might exile such individuals, forcing them to fend for themselves.{{Fact|date=March 2008}} The reason for such behaviors, and why these behaviors vary as they do, is unknown.
==True Crows and man==
Certain species have been considered pests; the [[Common Raven]], [[Australian Raven]] and [[Carrion Crow]] have all been known to kill weak lambs as well as eating freshly dead corpses probably killed by other means. [[Rook (bird)|Rooks]] have been blamed for eating grain in the UK and [[Brown-necked Raven]] for raiding date crops in desert countries.<ref>[[#Reference-idGoodwin1983|Goodwin 1983]]</ref>
==See also==
*[[Corvidae]]
*[[Scarecrow]]
*[[to eat boiled crow|Eating crow]]
*[[Ischys]] for the Greek myth of why the crow's feathers are black.
*[[Corvus (heraldry)|Corvus in heraldry]]
*[[Raven in mythology]]
*[[Cultural depictions of ravens]]
*[[West Nile Virus]]
==Notes and Citations==<!-- Condor105:139 -->
{{reflist|colwidth=35em}}
==References==
<!-- Please do not list citeweb references here unless it is cited more than once-->
*<!-- Gi --> {{wikicite|id=idGill2003|reference={{citejournal|title=Osteometry and Systematics of the Extinct New Zealand Ravens (Aves: Corvidae: Corvus).|url=http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=149547.|last=Gill, B. J.|coauthors=|journal=Journal of Systematic Palaeontology|year=2003|volume=1|issue=|pages=43-58|accessdate=2008-3-14}}}}
*<!-- Good -->{{wikicite|id=idGoodwin1983|reference=
{{citebook|last=Goodwin|first=D.|coauthors=|title=Crows of the World|isbn=0-7022-1015-3|pages=|year=1983|publisher=Queensland University Press, St Lucia, Qld.}}}}
*<!-- Hein -->{{wikicite|id=idHeinrich1991|reference=
{{citebook|last=Heinrich|first=Bernd|coauthors=|title=Ravens in Winter|isbn=0-679-73236-5|pages=|year=1991|publisher=Vintage Press}}}}
*<!-- Hein -->{{wikicite|id=idHeinrich1999|reference=
{{citebook|last=Heinrich|first=Bernd|coauthors=|title=Mind of the Raven: Investigations and Adventures with Wolf-Birds|isbn=978-0-06-093063-9|pages=|year=1999|publisher=New York: Cliff Street Books}}}}
*<!-- Kil -->{{wikicite|id=idKilham1991|reference=
{{citebook|last=Kilham|first=Lawrence|coauthors=|title=The American Crow and the Common Raven|isbn=0-890-96466-1|pages=|year=1991|publisher=Texas A&M University Press}}}}
*<!-- Wor -->{{wikicite|id=idWorthy2002|reference=
{{citebook|last=Worthy|first=Trevor H. |coauthors=Holdaway, Richard N.|title=The Lost World of the Moa: Prehistoric Life of New Zealand|isbn=0-253-34034-9|pages=|year=2002|publisher=Indiana University Press}}}}
==External links==
{{commonscat|Corvus}}
*[http://www.birds.cornell.edu/crows/crowfaq.htm Frequently Asked Questions About Crows]
*[http://www.birdhouses101.com/crow.asp Crow (BirdHouses101.com)]
*[http://www.crows.net/ crows.net: The Language & Culture of Crows]
*[http://nationalzoo.si.edu/Publications/ZooGoer/2005/6/Books_naturally_ND_05.cfm In the Company of Crows and Ravens], by John M. Marzluff and Tony Angell
*[http://www.clcookphoto.com/crows.htm Crow photographs and comments]
*[http://www.sciencemag.org/feature/data/crow/ Video of crow making and using tools]
*[http://users.ox.ac.uk/~kgroup/tools/tools_main.shtml More info on tool use by crows, with references]
*[http://ibc.hbw.com/ibc/phtml/familia.phtml?idFamilia=188 Crow videos] on the Internet Bird Collection
[[Category:Corvus|*]]
[[Category:Talking birds]]
[[Category:genera of birds]]