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Crow

2007 Schools Wikipedia Selection. Related subjects: Birds

                   iCrow
   Carrion Crow and Hooded Crow
   Carrion Crow
   and Hooded Crow
         Scientific classification

   Kingdom: Animalia
   Phylum:  Chordata
   Class:   Aves
   Order:   Passeriformes
   Family:  Corvidae
   Genus:   Corvus
            Linnaeus, 1758

                                   Species

   See text.

   The true crows are large passerine birds that comprise the genus
   Corvus. Ranging in size from the relatively small pigeon-sized 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 South America)
   and several offshore and oceanic islands (including Hawai‘i).

   In literary and fanciful usage, the collective noun for a group of
   crows is a murder. However, in practice most people, and especially
   scientists, use the more generic term flock.

Systematics

   Crow on a branch, Maruyama Kyo (1733-1795)
   Enlarge
   Crow on a branch, Maruyama Kyo (1733-1795)

   There is no good systematic approach to the genus at present.
   Generally, 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.

   The Neogene 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, documenting
   the evolution of the modern taxa. American crows are not as
   well-documented.

   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.

Species

   Australian and Melanesian species
     * Australian Raven C. coronoides
     * Forest Raven C. tasmanicus
          + Relict Raven C. (t.) boreus
     * 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. ( prehistoric)

   New Zealand species
     * Chatham Islands Raven, C. moriorum ( prehistoric)
     * New Zealand Raven, C. antipodum ( prehistoric)

   Pacific island species
     * Mariana Crow, C. kubaryi
     * Hawaiian Crow or ‘Alala C. hawaiiensis ( extinct in the wild,
       formerly C. tropicus)
     * High-billed Crow, C. impluviatus ( prehistoric)
     * Robust Crow, C. viriosus ( 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
     * Brown-necked Raven C. ruficollis
     * Fan-tailed Raven C. rhipidurus
     * Jackdaw C. monedula
     * Rook C. frugilegus
     * Hooded Crow C. cornix
          + Mesopotamian Crow, C. (c.) capellanus
     * Carrion Crow C. corone
     * Corvus larteti (fossil: Late Miocene of France)
     * Corvus antecorax (fossil: Early - Late Pleistocene of Europe; may
       be subspecies of Corvus corax
     * Corvus betfianus (fossil)
     * Corvus praecorax (fossil)
     * Corvus simionescui (fossil)
     * Corvus pliocaenus (fossil)
     * Corvus fossilis (fossil)
     * Corvus moravicus (fossil)
     * ?Corvus hungaricus (fossil)

   Holarctic species
     * Common Raven C. corax
          + Pied Raven, C. c. varius morpha leucophaeus (an extinct colour
            variant)

   North and Central American species
     * American Crow C. brachyrhynchos
     * 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
     * Puerto Rican Crow C. pumilis ( 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)

   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
   chronosubspecies have been described. These are featured under the
   respective species accounts.

Evolution

   They appear to have evolved in central Asia and radiated out into North
   America, Africa, Europe, and Australia.

   The latest evidence 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.

   For more information regarding relatives of the crows, such as magpies
   and jays, see Corvidae.

Behaviour

Calls

   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 behaviour 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

   Crow searching food from punctured wastebag
   Enlarge
   Crow searching food from punctured wastebag

   As a group, the crows show remarkable examples of intelligence. They
   top the avian IQ scale . Crows and ravens often score very highly on
   intelligence tests. Crows in the northwestern U.S. (a blend of Corvus
   brachyrhynchos and Corvus caurinus) 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", and have an intense rivalry with the area's less
   socially advanced ravens. One species, the New Caledonian Crow, has
   recently been intensively studied because of its ability to manufacture
   and use its own tools in the day-to-day search for food. Wild hooded
   crows in Israel have learned to use bread crumbs for bait-fishing.
   Crows will engage in a kind of midair jousting, or air-" chicken" to
   establish pecking order.

Colour and society

   Extra-specific uses of colour in crow societies
   Many crow species are all black. Most of their natural enemies, the
   raptors or " falconiformes", soar high above the trees, and hunt
   primarily on bright, sunny days when contrast between light and shadow
   is greatest. Crows take advantage of this by maneuvering themselves
   through the dappled shades of the trees, where their black colour
   renders them effectively invisible to their enemies above, in order to
   set up complex ambush attacks. Thus, their black coloring is of great
   strategic importance to their societies. It is perhaps here where we
   find the greatest difference between ravens and crows; ravens tend to
   soar high in the air as raptors do, and like raptors, are usually the
   target of ambushes by crows. Crows do not appear to perceive ravens as
   their own kind, but instead treat them as raptors.

   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,
   preying upon crows sleeping helplessly in their roosts. Presumably
   their dark colour is particularly helpful in blending into nighttime
   shadows. Crows also will often mob owls much more fiercely when they
   find them in daylight than they do hawks and other raptors. 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.

   Intra-specific uses of colour 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, while another group of the same species might exile such
   individuals, forcing them to fend for themselves. The reason for such
   behaviors, and why these behaviors vary as they do, has yet to be
   studied.

Mythology and folklore

   The Twa Corbies by Arthur Rackham
   Enlarge
   The Twa Corbies by Arthur Rackham

   Crows, and especially ravens, often feature in legends or mythology as
   portents or harbingers of doom or death, because of their dark plumage,
   unnerving calls, and tendency to eat carrion. They are commonly thought
   to circle above scenes of death such as battles. The Child ballad The
   Three Ravens depicts three ravens discussing whether they can eat a
   dead knight, but finds that his hawk, his hound, and his true love
   prevent them; in the parody version The Twa Corbies, these guards have
   already forgotten the dead man, and the ravens can eat their fill.
   Their depiction of evil has also led to some exaggeration of their
   appetite. In Pirates of the Caribbean: Dead Man's Chest, The Omen II
   and Exorcist: The Beginning, crows are shown tearing out people's eyes
   while they are still alive. This, of course, does not happen as crows
   can distinguish between carrion and living people.

   In Native American folklore, Crow is often seen as a similar trickster
   to Coyote. However, Crow's tricks tend to be more out of malice and
   they rarely (if ever) are portrayed as a hero. One possible explanation
   for this is that crows are often considered a pest to crops, which the
   tribes who came up with the stories featuring Crow needed to survive.

   In the Epic of Gilgamesh, the Chaldean myth, the character Utnapishtim
   releases a dove and a raven to find land, similar to what Noah does in
   the book of Genesis. However, in the Epic of Gilgamesh, the dove merely
   circles and returns. Only then does Utnapishtim send forth the raven,
   who does not return. Utnapishtim extrapolates from this that the raven
   has found land, which is why it hasn't returned. This would seem to
   indicate some acknowledgement of crow intelligence, which may have been
   apparent even in ancient times, and to some might imply that the higher
   intelligence of crows, when compared to other birds, is striking enough
   that it was known even then.

   In occult circles, distinctions are sometimes made between crows and
   ravens. In mythology and folklore as a whole, crows tend to be symbolic
   more of the spiritual aspect of death, or the transition of the spirit
   into the afterlife, whereas ravens tend more often to be associated
   with the negative (physical) aspect of death. However, few if any
   individual mythologies or folklores make such a distinction, and there
   are ample exceptions. Another reason for this distinction is that while
   crows are typically highly social animals, ravens don't seem to
   congregate in large numbers anywhere but a) near carrion where they
   meet seemingly by chance, or b) at cemeteries, where large numbers
   sometimes live together, even though carrion there is no more available
   (and probably less attainable) than any road or field.

   Amongst Neopagans, crows are often thought to be highly psychic and are
   associated with the element of ether or spirit, rather than the element
   of air as with most other birds. This may in part be due to the
   long-standing occult tradition of associating the colour black with
   "the abyss" of infinite knowledge (see akasha), or perhaps also to the
   more modern occult belief that wearing the "colour" black aids in
   psychic ability, as it absorbs more electromagnetic energy, since
   surfaces appear black by absorbing all frequencies in the visible
   spectrum, reflecting no colour.

Gods and goddesses associated with crows and ravens

   A very incomplete list includes the eponymous Pacific Northwest Native
   figures Raven and Crow, the ravens Hugin and Munin, who accompany the
   Norse god Odin, the Celtic goddesses the Mórrígan and/or the Badb
   (sometimes considered separate from Mórrígan), and Shani, a Hindu god
   who travels astride a crow. In Greek mythology, it was believed that
   when the crows gave bad news to the goddess Athena, she flew into a
   rage, and cursed their feathers to be black. Myths in India -Hindu it
   is believed that people who died will take food and offerings through a
   variety of crows called "Bali kkakka". Every year people whose parents
   or relatives died will offer food to crows as well as cows on the
   Shradha day.

Virus

   The American crow is very susceptible to the West Nile virus, a disease
   just recently introduced in North America. American crows usually die
   within one week of acquiring the disease with only very few surviving
   exposure. Crows are so affected by the disease that their deaths are
   now serving as an indicator of the West Nile Virus’activity in an area.

Trivia

   The city of Moss, Norway has a crow in its coat-of-arms.

   Retrieved from " http://en.wikipedia.org/wiki/Crow"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
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