Crows

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Crow
American Crow (Corvus brachyrhynchos)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Corvidae
Genus: Corvus
Linnaeus, 1758

Crows /kr/ form the genus Corvus 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 for 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. Crows 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, more poetically, a murder.[1]

Recent research has found some crow species capable not only of tool use but of tool construction as well.[2] Crows are now considered to be among the world’s most intelligent animals.[3] The Jackdaw and the European Magpie have been found to have a nidopallium approximately the same relative size as the functionally equivalent neocortex in chimpanzees and humans, and significantly larger than is found in the gibbon.[4]

Contents

[edit] Description

in flight

Jungle Crow (Corvus macrorhynchos) scavenging on a dead shark at a beach in Kumamoto, Japan

Corvus species are all black or black with little white or gray plumage. They are stout with strong bills and legs. The sexes are not very different in appearance.

[edit] Evolutionary history and systematics

Crows are believed to have evolved in central Asia and radiated out into North America, Africa, Europe, and Australia.

The latest evidence[5] regarding the crow’s evolution indicates descent within the Australasian family Corvidae. However, the branch that would produce the modern groups such as jays, magpies and large predominantly black Corvus had left Australasia and were concentrated in Asia by the time the Corvus evolved. Corvus has since re-entered Australia (relatively recently) and produced five species with one recognized sub-species.[citation needed]

The genus was originally described by Linnaeus in his 18th century work Systema Naturae.[6] The name is derived from the Latin corvus meaning “raven”.[7]

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 (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 not a good systematic approach to the genus at present. In general, it is assumed that the 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/Collared/House Crow complex is certainly closely related to each other, the situation is not at all clear regarding the Australian/Melanesian 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.[citation needed]

Closeup of the upper body of a Jackdaw (Corvus monedula)

The fossil record of crows is rather dense in Europe, but the relationships among most prehistoric species are not clear.

[edit] Species

[edit] Behavior

[edit] Calls

Crows make a wide variety of calls or vocalizations. Crows have also been observed to respond to calls of other species; this behavior is, it is presumed, learned because it varies regionally. Crows’ vocalizations are complex and poorly understood. Some of the many vocalizations that crows make are a “Koww”, usually echoed back and forth between birds, a series of “Kowws” in discrete units, 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).

[edit] Intelligence

As a group, crows show remarkable examples of intelligence. Crows and ravens often score very highly on intelligence tests. Certain species top the avian IQ scale.[8] Wild hooded crows in Israel have learned to use bread crumbs for bait-fishing.[9] Crows will engage in a kind of mid-air jousting, or air-”chicken” to establish pecking order. Crows have been found to engage in feats such as sports,[10] tool use, the ability to hide and store food across seasons, episodic-like memory, and the ability to use individual experience in predicting the behavior of environmental conspecifics.[11]

One species, the New Caledonian Crow, has also been intensively studied recently because of its ability to manufacture and use its own tools in the day-to-day search for food. These tools include “knives” cut from stiff leaves and stiff stalks of grass.[12] Another skill involves dropping tough nuts into a trafficked street and waiting for a car to crush them open.[13][14] 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.[15][16] Crows in Queensland, Australia have learned how to eat the toxic cane toad by flipping the cane toad on its back and violently stabbing the throat where the skin is thinner, allowing the crow to access the non-toxic innards; their long beaks ensure that all of the innards can be removed.[17][18]

Recent research suggests that crows have the ability to recognize one individual human from another by facial features.[19]

[edit] Diet

Crows are omnivorous, and their diet is very diverse. They will eat almost anything, including other birds, fruits, nuts, mollusks, earthworms, seeds, frogs, eggs, nestlings, mice and carrion. The origin of placing scarecrows in grain fields resulted from the crow’s incessant damaging and scavenging, although crows assist farmers by eating insects otherwise attracted to their crops.[20]

[edit] Life span and disease

Crows reach sexual maturity around the age of 3 years for females and 5 years for males. Some crows may live to the age of 20, and the oldest known American crow in the wild was almost 30 years old.[21]

The oldest captive crow documented died at age 59.[22] The American crow is highly susceptible to the recently introduced North American strain of West Nile virus.[23] American crows typically die within one week of acquiring the disease and very few survive exposure.

[edit] Conservation status

The Hawaiian Crow or ʻalala (Corvus hawaiiensis) is nearly extinct; only a few dozen birds survive in captivity. The Hawaiian Crow is listed as “extinct in the wild” by the US fish and wildlife services.

Two species of crow have been listed as endangered by the U.S. Fish and Wildlife Service: The Hawaiian Crow and the Mariana Crow.[24] The American Crow, despite having its population reduced by 45% since 1999 by the West Nile Virus, is considered a Species of Least Concern.

[edit] Hunting

There is no bag limit when taken during the “crow hunting season.” According to the US Code of Federal Regulations, crows may be taken without a permit in certain circumstances. USFWS 50 CFR 21.43 (Depredation order for blackbirds, cowbirds, grackles, crows and magpies) states that a Federal permit is not required to control these birds “when found committing or about to commit depredations upon ornamental or shade trees, agricultural crops, livestock, or wildlife, or when concentrated in such numbers and manner as to constitute a health hazard or other nuisance,” provided that

  • none of the birds killed or their parts are sold or offered for sale,
  • anyone exercising the privileges granted by this section shall permit any Federal or State game agent free and unrestricted access over the premises where the operations have been or are conducted and will provide them with whatever information required by the officer, and
  • nothing in the section authorizes the killing of such birds contrary to any State laws and that the person needs to possess whatever permit may be required by the State.

[edit] In human culture

The Common Raven and Carrion Crow have been blamed for killing weak lambs and are often seen eating freshly dead corpses probably killed by other means. The Australian raven has been documented chasing, attacking and seriously injuring lambs.[25] Rooks have been blamed for eating grain in the UK and Brown-necked Raven for raiding date crops in desert countries.[26]

In Auburn, New York (USA), 25,000 to 50,000 American Crows (C. brachyrhynchos) have taken to roosting in the small city’s large trees during winter since around 1993.[27] In 2003, a controversial, organized crow hunt proved ineffective at reducing their numbers and the problem (concerns for public health and the sheer noise of so many crows) continues.[28]

At a Technology Entertainment Design conference in March 2008, Joshua Klein presented the potential use of a vending machine for crows. He suggested the crows could be trained to pick up waste and the vending machine would be designed to give a reward in exchange for the trash.[29]

Crows have been shown to have the ability to visually recognize individual humans, and to transmit information about “bad” humans by squawking.[30]

[edit] Myth and spirituality

The Twa Corbies by Arthur Rackham

In Irish mythology, crows are associated with Morrigan, the goddess of war and death.[31]

The god Bran the Blessed -whose name means ‘crow’ or ‘raven’- is associated with corvids and death; tradition holds that Bran’s severed head is buried under the Tower of London, facing France- a possible genesis for the practice of keeping ravens in the Tower, said to protect the fortunes of Britain. In Cornish folklore, crows -magpies particularly- are associated with death and the ‘otherworld’, and proscribes respectful greeting. The origin of ‘counting crows’ as augury is British; however, the British version rather is to ‘count magpies’ – their black and white pied colouring alluding to the realms of the living and dead.

In Norse mythology, Huginn and Muninn are a pair of ravens that range the entire world, Midgard, bringing the god Odin information.

In Australian Aboriginal mythology, Crow is a trickster, culture hero, and ancestral being. Legends relating to Crow have been observed in various Aboriginal language groups and cultures across Australia; these commonly include stories relating to Crow’s role in the theft of fire, the origin of death, and the killing of Eagle’s son.

Crow on a branch, Maruyama Ōkyo (1733–1795)

The Chaldean myth the Epic of Gilgamesh, Utnapishtim releases a dove and raven to find land; however, the dove merely circles and returns. Only then does Utnapishtim send forth the raven, which does not return, and Utnapishtim concludes the raven has found land.[32]

According to Ovid’s Metamorphoses, in Greek mythology, the god Apollo became enraged when the crow exposed his lover Coronis’ tryst with a mortal, his ire transmuting the crow’s feathers from white to black.[33]

In the Story of Bhusunda, a chapter of the Yoga Vasistha, a very old sage in the form of a crow, Bhusunda, recalls a succession of epochs in the earth’s history, as described in Hindu cosmology. He survived several destructions, living on a wish-fulfilling tree on Mount Meru.[34] Crows are also considered ancestors in Hindiusm and during Śrāddha the practice of offering food or pinda to crows is still in vogue.[35]

Crows are mentioned often in Buddhism, especially Tibetan disciplines. The Dharmapala (protector of the Dharma) Mahakala is represented by a crow in one of his physical/earthly forms.[citation needed]

In Japanese mythology, a three-legged crow called Yatagarasu (八咫烏?, “eight-hand-crow”)[36] is depicted.[37]

In Korean mythology, there is a three-legged crow known as Samjokgo (hangul: 삼족오; hanja: 三足烏).[citation needed]

In Chinese mythology, the world originally had ten suns embodied as ten crows, which rose in the sky one at a time. When all ten decided to rise at once, the effect was devastating to crops, so the gods sent their greatest archer Houyi, who shot down nine crows and spared only one.[citation needed]

In Hinduism, crows are thought of carriers of information. They give omens to people regarding their situations. For example : When a crow crows in front of a person’s house, he is expected to have special visitors that day. Also, in Hindu literature, crows have great memories which they use to give information.[citation needed]

Indian Crow

Ancient Greek authors tell how a jackdaw, being a social creature, may be caught with a dish of oil that it falls into while looking at its own reflection.[38] The Roman poet Ovid saw them as a harbinger of rain (Amores 2,6, 34).[39] In Greek legend, a princess Arne was bribed with gold by King Minos of Crete, and was punished for her avarice by being transformed into an equally avaricious jackdaw, who still seeks shiny things.[40] In Aesop’s Fables, the jackdaw embodies stupidity in one tale, by starving while waiting for figs on a fig tree to ripen, and vanity in another – the daw sought to become king of the birds with borrowed feathers, but was shamed when they fell off.[39] Pliny notes how the Thessalians, Illyrians and Lemnians cherished jackdaws for destroying grasshoppers’ eggs. The Veneti are fabled to have bribed the jackdaws to spare their crops.[38] Another ancient Greek and Roman adage runs, “The swans will sing when the jackdaws are silent,” meaning that educated or wise people will speak after the foolish become quiet.[41] In reality, corvids are among the most intelligent birds in the world, and this traditional association with ignorance is quite inaccurate.

[edit] See also

[edit] References

  1. ^ “Murder of Crows, etc.”. Word-detective.com. http://www.word-detective.com/2009/02/22/murder-of-crows-etc. Retrieved 2011-11-12.
  2. ^ Winkler, Robert (August 8, 2002). “Crow Makes Wire Hook to Get Food”. National Geographic. http://news.nationalgeographic.com/news/2002/08/0808_020808_crow.html. Retrieved 6 February 2011.
  3. ^ “A Murder of Crows”. Nature. PBS video. 2010-10-24. http://video.pbs.org/video/1621910826/#. Retrieved 6 February 2011. “New research indicates that crows are among the brightest animals in the world.
  4. ^ Rogers, Lesley J.; Kaplan, Gisela T. (2004). Comparative vertebrate cognition: are primates superior to non-primates?. New York, New York: Springer. p. 9. ISBN 0-306-47727-0. http://books.google.com.au/books?id=e021s7atsicC&pg=PA9&dq=Comparative+vertebrate+cognition:+are+primates+superior+to+non-primates?+jackdaw&hl=en&sa=X&ei=68KzT8aDHc6WmQW2kvycBQ&ved=0CDYQ6AEwAA#v=onepage&q&f=false.
  5. ^ “Phylogeny and diversification of the largest avian radiation – Barker et al., 10.1073/pnas.0401892101 – Proceedings of the National Academy of Sciences”. Pnas.org. http://www.pnas.org/cgi/content/abstract/0401892101v1. Retrieved 2011-11-12.
  6. ^ (Latin) Linnaeus, C (1758). Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.. Holmiae. (Laurentii Salvii). p. 824. http://dz1.gdz-cms.de/index.php?id=img&no_cache=1&IDDOC=265100.
  7. ^ Simpson, D.P. (1979). Cassell’s Latin Dictionary (5 ed.). London: Cassell Ltd.. p. 883. ISBN 0-304-52257-0.
  8. ^ Rincon, Paul (2005-02-22). “Science/Nature | Crows and jays top bird IQ scale”. BBC News. http://news.bbc.co.uk/1/hi/sci/tech/4286965.stm. Retrieved 2011-11-12.
  9. ^ ד”ר אורן חסון: יחסים, אהבה, זוגיות, תקשורת בין-אישית (English)[unreliable source?]
  10. ^ [1] Crow tubing upon a slide (video)
  11. ^ Prior H. et al. (2008). “Mirror-Induced Behavior in the Magpie (Pica pica): Evidence of Self-Recognition”. PLoS Biology (Public Library of Science) 6 (8): e202. doi:10.1371/journal.pbio.0060202. PMC 2517622. PMID 18715117. http://biology.plosjournals.org/archive/1545-7885/6/8/pdf/10.1371_journal.pbio.0060202-L.pdf. Retrieved 2008-08-21.
  12. ^ New Caledonian Crow#Tool making
  13. ^ Shettleworth, Sara J. (2010). Cognition, Evolution, and Behavior. Oxford University Press. pp. 3–4. ISBN 978-0-19-531984-2. http://books.google.com/books?id=-Qs1qGys0AwC&pg=PA3.
  14. ^ See also the video “Red light runners”, from the BBC’s The Life of Birds
  15. ^ “Crows Bend Twigs Into Tools”, Discovery Channel
  16. ^ See also the video “Crow bars”, from the BBC’s The Life of Birds
  17. ^ Katrina Bolton (2007-09-15). “Toads fall victim to crows in NT – ABC News (Australian Broadcasting Corporation)”. Abc.net.au. http://www.abc.net.au/news/stories/2007/09/15/2033759.htm. Retrieved 2011-11-12.
  18. ^ “Cane Toad (Bufo marinus)”. Ozanimals.com. http://www.ozanimals.com/Frog/Cane-Toad/Bufo/marinus.html. Retrieved 2011-11-12.
  19. ^ Nijhuis, Michelle (August 25, 2008). “Friend or Foe? Crows Never Forget a Face, It Seems”. The New York Times. http://www.nytimes.com/2008/08/26/science/26crow.html. Retrieved 6 February 2011.
  20. ^ Crow Facts. crowbusters.com
  21. ^ McGowan, K.J. “Frequently Asked Questions About Crows”, Cornell Lab of Ornithology
  22. ^ Crow Believed to Be Oldest in World Dies. Associated Press via Washington Post (2006-07-07)
  23. ^ “Why West Nile virus kills so many crows”, Penn State Center for Infectious Disease Dynamics
  24. ^ “Pacific Region Endangered Species, U.S. Fish and Wildlife Service”. Fws.gov. 2011-06-23. http://www.fws.gov/pacific/ecoservices/endangered/recovery/5yearactive.html. Retrieved 2011-11-12.
  25. ^ G. Alexander, T. Mann, C. J. MuIhearn, I. C. R. Rowly, D. Williams, and D. Winn, 1967 “Activities of foxes and crows in a flock of lambing ewes”, Australian Journal of Experimental Agriculture and Animal Husbandry 7
  26. ^ Goodwin D. (1983). Crows of the World. Queensland University Press, St Lucia, Qld. ISBN 0-7022-1015-3.
  27. ^ “Auburn NY Crow Roost and lighting changes”. Cnylinks.com. http://www.cnylinks.com/crows/. Retrieved 2011-11-12.
  28. ^ “The Citizen, Auburn NY”. Auburnpub.com. 2002-06-14. http://www.auburnpub.com/articles/2003/02/03/opinion/our_view/ourview01.txt. Retrieved 2011-11-12.
  29. ^ Klein, Joshua (2008). “The amazing intelligence of crows”. TED conference. http://www.ted.com/index.php/talks/joshua_klein_on_the_intelligence_of_crows.html. Retrieved 9 July 2008.
  30. ^ The Crow Paradox by Robert Krulwich. Morning Edition, National Public Radio. 27 July 2009.
  31. ^ Leeming, David Adams (2005). “Crows and ravens”. The Oxford companion to world mythology. Oxford University Press. p. 86. ISBN 978-0-19-515669-0. http://books.google.com/books?id=kQFtlva3HaYC&pg=PA86.
  32. ^ Kovacs, Maureen Gallery (1989). The epic of Gilgamesh. Stanford University Press. p. 102. ISBN 978-0-8047-1711-3. http://books.google.com/books?id=YYxEd9c0EUYC&pg=PA102.
  33. ^ Dixon-Kennedy, Mike (1998). “Coronis/Corvus”. Encyclopedia of Greco-Roman mythology. ABC-CLIO. p. 93. ISBN 978-1-57607-129-8. http://books.google.com/books?id=2U7okUE3PIcC&pg=PA93.
  34. ^ Cole, Juan R.I. Baha’u'llah on Hinduism and Zoroastrianism: The Tablet to Mirza Abu’l-Fadl Concerning the Questions of Manakji Limji Hataria.
  35. ^ Vasudevan, Vidia (2001-07-26). “It’s a crow’s day”. The Hindu (Chennai, India). http://www.hindu.com/2001/07/26/stories/13261289.htm.
  36. ^ Picken, Stuart D.B. (1994). Essentials of Shinto: an analytical guide to principal teachings. Greenwood Publishing Group. p. 96. ISBN 978-0-313-26431-3. http://books.google.com/books?id=yA3_QqC6pPgC&pg=PA96.
  37. ^ Como, Michael (2009). Weaving and binding: immigrant gods and female immortals in ancient Japan. University of Hawaii Press. pp. 100–103. ISBN 978-0-8248-2957-5. http://books.google.com/books?id=-UNEhdX6ePMC&pg=PA100.
  38. ^ a b D’Arcy Wentworth Thompson, A Glossary of Greek Birds. Oxford, 1895. p. 89.
  39. ^ a b de Vries, Ad (1976). Dictionary of Symbols and Imagery. Amsterdam: North-Holland Publishing Company. p. 275. ISBN 0-7204-8021-3.
  40. ^ Graves, R (1955). “Scylla and Nisus”. Greek Myths. London: Penguin. p. 308. ISBN 0-14-001026-2.
  41. ^ Collected Works of Erasmus: Adages: Ivi1 to Ix100. Translated by Roger A. Mynors. University of Toronto Press, 1989. p. 314.

[edit] Further reading

[edit] External links

source: http://en.wikipedia.org/wiki/Crow

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