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|American Crow (Corvus brachyrhynchos)|
|American Crow (Corvus brachyrhynchos)|
Crows // 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 South America) and several offshore and oceanic 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.
Recent research has found some crow species capable not only of tool use but of tool construction as well. Crows are now considered to be among the world's most intelligent animals. 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.
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.
The latest evidence 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.
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.
The fossil record of crows is rather dense in Europe, but the relationships among most prehistoric species are not clear.
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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).
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. Wild hooded crows in Israel have learned to use bread crumbs for bait-fishing. 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, 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.
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. Another skill involves dropping tough nuts into a trafficked street and waiting for a car to crush them open. 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. 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.
Recent research suggests that crows have the ability to recognize one individual human from another by facial features.
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.
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.
The oldest captive crow documented died at age 59.
The American crow is highly susceptible to the recently introduced North American strain of West Nile virus. American crows typically die within one week of acquiring the disease and very few survive exposure.
Two species of crow have been listed as endangered by the U.S. Fish and Wildlife Service: The Hawaiian Crow and the Mariana Crow. The American Crow, despite having its population reduced by 45% since 1999 by the West Nile Virus, is considered a Species of Least Concern.
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
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. Rooks have been blamed for eating grain in the UK and Brown-necked Raven for raiding date crops in desert countries.
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. 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.
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.
Though humans cannot generally tell individual crows apart, crows have been shown to have the ability to visually recognize individual humans, and to transmit information about "bad" humans by squawking.
In Irish mythology, crows are associated with Morrigan, the goddess of war and death. The god Bran the Blessed whose names means 'crow' or 'raven' is associated with corvids and death. His severed head is said to be buried under the Tower of London facing toward France, a possible origin for the keeping of ravens in the Tower, which are said to protect the fortunes of Britain. In Cornish folklore crows and particularly magpies are again associated with death and the 'otherworld', and must always be greeted with respect. The origin of 'counting crows' as augury is British; however the British versions rather count magpies - their black and white pied colouring reflecting the realms of both the living and the dead.
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.
In the Epic of Gilgamesh, the Chaldean myth, the character Utnapishtim releases a dove and a raven to find land, however, 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.
According to Ovid's Metamorphoses, in classical Greek mythology, when the crow told the god Apollo that his lover Coronis was cheating on him with a mortal, he became very angry, and part of that anger was directed at the crow, whose feathers he turned from white to black.
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. Crows are also considered ancestors in Hindiusm and during Śrāddha the practice of offering food or pinda to crows is still in vogue.
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.
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. The Roman poet Ovid saw them as a harbinger of rain (Amores 2,6, 34). 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. 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. 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. 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. In reality, corvids are among the most intelligent birds in the world, and this traditional association with ignorance is quite inaccurate.
|Wikisource has the text of the 1911 Encyclopædia Britannica article Crow.|
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