Large, intelligent songbirds, members of the genus Corvus occur on all continents except for South America and Antarctica. Larger forms are called "ravens," most are called "crows" and the two smallest (in their own sub-genus) are called "jackdaws." The palette for their plumage is dominated by black, with some species showing gray, white, or rarely brown. Making up for the lack of visual variety, crows and ravens utter a wide variety of sounds, from loud and harsh cawing to softer rattles and knocks and coos. Most species prefer open areas and are often seen foraging on the ground. Though many species thrive in areas highly impacted by humans, and some have become nuisances or invasives, several island species are threatened.
The genus includes several species notable for their behavior. New Caledonian Crows are accomplished toolmakers. Several species drop clams or nuts onto roadways to crack them open. Many species are featured in mythology and art.
Water temperature and chemistry ranges based on 26 samples.
Depth range (m): 0 - 0
Temperature range (°C): 7.710 - 11.855
Nitrate (umol/L): 1.075 - 12.829
Salinity (PPS): 6.428 - 35.184
Oxygen (ml/l): 6.128 - 8.179
Phosphate (umol/l): 0.231 - 0.734
Silicate (umol/l): 1.816 - 12.889
Temperature range (°C): 7.710 - 11.855
Nitrate (umol/L): 1.075 - 12.829
Salinity (PPS): 6.428 - 35.184
Oxygen (ml/l): 6.128 - 8.179
Phosphate (umol/l): 0.231 - 0.734
Silicate (umol/l): 1.816 - 12.889
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.
Based on studies in:
Canada: Manitoba (Grassland)
This list may not be complete but is based on published studies.
Known prey organisms
Based on studies in:
Canada: Manitoba (Grassland)
USA: Massachusetts, Cape Ann (Marine)
USA: Arizona, Sonora Desert (Desert or dune)
India, Rajasthan Desert (Desert or dune)
This list may not be complete but is based on published studies.
Life History and Behavior
Crows are one of the most intelligent and most sociable creatures. In a murder of crows it is like they are all family. What I have observed was that sometimes when a crow was flying there is usually another member of the murder accompanying, or there is one crow perched in a tree while the other flys just in the range of the calls.
Another thing I observed was that there are murder members located at strategic points which I belive is to defend the young from predators. One thing that really amazed me about there sociable capacity is the way that they spread news. Just by making their calls the alerted every member of the flock(murder) about my presence. But the truely amazing thing was that the news spread in a few seconds. This point proves that we have many similarities to these so called "pests."
Molecular Biology and Genetics
Statistics of barcoding coverage
Specimens with Sequences:176
Specimens with Barcodes:174
Species With Barcodes:19
Corvus is a widely distributed genus of birds 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 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. The members 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 a murder.
Recent research has found some crow species capable of not only tool use but also tool construction. Crows are now considered to be among the world's most intelligent animals with an encephalization quotient approaching that of some apes.
In medieval times, the crow was thought to live an abnormally long life. They were also thought to be monogamous throughout their long lives. It was thought that the crow could predict the future, in that it was thought to predict rain and reveal ambushes. Crows were also thought to lead flocks of storks while they crossed the sea to Asia.
- 1 Description
- 2 Evolutionary history and systematics
- 3 North American urban crow history
- 4 Behavior
- 5 Diet
- 6 Reproduction
- 7 Life span and disease
- 8 Conservation status
- 9 Problems with crows and methods of control
- 10 As a food supplement
- 11 In human culture
- 12 See also
- 13 References
- 14 Further reading
- 15 External links
Corvus species are all black or black with little white or grey plumage. They are stout with strong bills and legs. There is limited sexual dimorphism.
Evolutionary history and systematics
The latest evidence regarding the 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 being moved later 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 members of the Carrion/Collared/house crow complex are certainly closely related, 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.
North American urban crow history
Crows are found in major cities across the world, and there has been a major increase in the number of crows in urban settings since the 1900s. Historical records suggest that the population of American crows found in North America has been growing steadily since the introduction of European colonization, and spread east to west with the opening of the frontier. Crows were uncommon in the Pacific Northwest in the 1900s, except in riparian habitats. Populations in the west increased substantially from the late 1800s to mid 1900s. Crows spread along with agriculture and urbanization into the western part of North America. 
Crows gather in large communal roosts between 200 and tens of thousands of individuals during non-breeding months, particularly in the winter. These gatherings tend to happen near large food sources such as garbage dumps and shopping centers. 
There are countless recorded incidents of crows at play. Many behaviourists see play as an essential quality in intelligent animals.
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Crows and the other members of the genus make a wide variety of calls or vocalizations. Crows have also been observed to respond to calls of other species; presumably, this behavior is 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 they vary regionally. In many species, the pattern and number of the numerous vocalizations have been observed to change in response to events in the surroundings (e.g. arrival or departure of crows). Crows can imitate calls of other birds. A local crow was observed, for many years now, to "blend in" with pigeons and imitate a pigeon's cooing in order to feed on food fed to pigeons by humans. This crow "pretends" to be a pigeon to get food. Call sounds almost like pigeon cooing but still different from real pigeon's cooing. The same crow made usual (normal) crow calls when it was observed among other crows.
As a group, crows show remarkable examples of intelligence. Natural history books from the 18th century recount an often-repeated, but unproven anecdote of "counting crows" — specifically a crow whose ability to count to five (or four in some versions) is established through a logic trap set by a farmer. 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 tools in the day-to-day search for food. On 5 October 2007, researchers from the University of Oxford, England, presented data acquired by mounting tiny video cameras on the tails of New Caledonian crows. They pluck, smooth and bend 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.
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.
Crows have demonstrated the ability to distinguish individual humans by recognizing facial features.
Evidence also suggests that they are one of the few non-human animals capable of displacement (communicating about things that are happening in a different spatial or temporal location to the here and now).
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. Clutch size is approximately 3-9 eggs, and the nesting period lasts between 20 and 40 days. Young from previous years often help nesting pairs protect a nest and feed nestlings. 
Life span and disease
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.
Problems with crows and methods of control
Intelligence and social structures makes most crow species, or Corvids, an adaptable and opportunistic species. Crows frequently cause damage to crops and property, strew trash, and transfer disease. In densely populated areas around the world, Corvid species are generally regarded as nuisance animals. Crows are protected in the U.S. under the federal Migratory Bird Treaty Act of 1918, but because of their perceived destructive nature, control of the species is allowed in certain areas. Because of the Corvids' intelligence, their control is an expensive and perplexing proposition. Methods for control include hunting, chemical immobilization, harassment scare tactics, and trapping, as well as others. Before any measure is used to confine, trap, kill, poison, immobilize, or alter the habits of any wild bird species a person must check local, state, and federal regulations pertaining to such actions.
|The examples and perspective in this section deal primarily with the United States and do not represent a worldwide view of the subject. (July 2014)|
In the United States, despite crows being protected under the Federal Migratory Bird Treaty Act of 1918, hunting is allowed under state and federal regulation. Crow hunting is considered a sport in rural areas of the U.S. because the birds are not considered a tasty traditional game species. Some cultures do treat various Corvid species as a food source. Liability and possible danger to persons and property limit the use of hunting or shooting as control methods in urban areas. Crows' wariness and cunning make it difficult to harvest crows in sufficient numbers.
Poisoning has been used in the past as a method of controlling crow populations, usually in urban areas or areas of large crow populations. Liability, cost associated with the chemicals, permits and manpower, threat to non-target species such as raptors, and availability of chemicals makes poisoning less than a desirable method for control.
Scare tactics have been the most widely used aversion tactic for crows in areas frequented by humans and domestic animal species. This is a safe method that does not require constant maintenance or manpower to operate or monitor. However, Corvids quickly become habituated to most tactics such as blast cannons, predator decoys, and traditional scarecrows. Greater success has been achieved by adding sound and motion to predator decoys to mimic a distressed crow being caught by a predator such as an owl or hawk. Work is currently being done which uses multiple aversion techniques in one area. The theory is that multiple techniques used together will confuse the crows, thereby lessening the probability of habituation to stimuli.
Trapping is a rarely used technique in the U.S. but is being used with success in parts of Europe and Australia. The ladder-style trap (e.g., Australian Crow Trap or Modified Australian Crow Trap) seems to be the most effective in crow-trapping techniques. Ladder traps are constructed in such a way that unintentional catch of non-target species is avoided. If a non-target species is caught, it can be easily released without harm to the bird. The traps are cost-efficient because they are inexpensive and simple to construct, and require little manpower to monitor. The bait used in the traps can also be specific to Corvids. Carrion, grains, unshelled raw peanuts, and shiny objects in the trap are effective baits. When removing crows from a ladder trap, one living crow is left as an extremely effective decoy for other crows. Trapping is considered the most humane method for crow removal because the crows can be relocated without harm or stress. However, most wild birds in general have a knack for returning to their home ranges.
Other methods have been used with little or limited success. Lasers have been used successfully to remove large flocks of birds from roost structures in urban areas, but success in keeping crows off roosts has been short lived. Homeowners can reduce the presence of crows by keeping trash stored in containers, feeding pets indoors, and hanging tin pie-pans or reflective gazing globes around garden areas.
As a food supplement
Crows were hunted for survival by Curonians, a Baltic tribe, when common food was exhausted and the landscape changed so that farming was not as productive during the 18th and 19th centuries. Fishermen supplemented their diet by gathering coastal bird eggs and preserving crow meat by salting and smoking it. It became a traditional food for poor folk and is documented in a poem, The Seasons by K. Donelaitis. After the non-hunting policy was lifted by the Prussian government in 1721–24 and alternative food supplies increased, the practice was forgotten. The tradition reemerged after World War I; in marketplaces, it was common to find butchered crows which were sought after and bought by townsfolk. The hunted crows were not the local, but the migrating ones; each year during the spring and autumn crows migrated via the Curonian Spit between Finland and the rest of Europe. In 1943, the government even issued a hunting quota for such activities. Crows were usually caught by attracting them with smoked fish or grains soaked in spirits and then collecting them with nets. It was a job for the elderly or young who were unable to go to sea to fish, and it was common to catch 150 to 200 birds during a hunting day.
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. Rooks have been blamed for eating grain in the UK and brown-necked raven for raiding date crops in desert countries.
In Auburn in the U.S. state of New York, 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 garbage.
Crows have been shown to have the ability to visually recognize individual humans, and to transmit information about "bad" humans by squawking.
Myth and spirituality
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 Sweden, ravens are held to be the ghosts of murdered men. In Denmark, the night raven is considered an exorcised spirit. There is a hole in its left wing where the stake used to exorcise it was driven into the earth. Those looking through the hole will become a night raven themselves.
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.
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.
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.
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.
In Chinese mythology, the world originally had ten suns either spiritually embodied as ten crows and/or carried by ten crows: 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. This mythology comes from a text in Shanhaijing, among other sources.
In Hinduism, crows are thought of as 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. There is a lot of symbolism associated with the crow in the Hindu faith. On a positive note, Crows are often associated with worship to ancestors because they are believed to be embodying the souls of the recently deceased. On the other hand, there are a lot of negative associations with crows in Hinduism. Crows are believed to be connected with both the gods and goddesses, particularly the unfavorable or harmful ones like Sani. They are often seen as dark and dangerous. Crows are also seen as being a sign of bad luck or evil in some practices. However, recently their perception has been a topic of discussion, and it has been concluded that it is unclear.
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 Hinduism and during Śrāddha, the practice of offering food or pinda to crows is still in vogue.
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, 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 jackdaw 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. However, there is one other Aesop Fable where the crow is depicted as very cunning. He comes up to a pitcher and knows that his beak is too short to reach the water and if he tips it over, all the water will fall out. The crow then proceeds to pick up pebbles and places them in the pitcher so the water may rise and he can reach it to relieve his thirst.
- Corvus (heraldry)
- Eating crow
- Ischys for the Greek myth of why the crow's feathers are black.
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The pied raven (Corvus corax varius morpha leucophaeus) was a colour morph of the North Atlantic subspecies of the Common Raven which was only found on the Faroe Islands and has disappeared since the mid twentieth century. It had large areas of white feathering, most frequently on the head, the wings and the belly, and its beak was light brown. Apart from that, it looked like the black ravens (morpha typicus).
In modern Faroese, the bird is called hvítravnur ("White Raven"), older name gorpur bringu hvíti ("White-chested Corbie"). Normal individuals of the subspecies varius, which is found on Iceland and the Faroe Islands, already show a tendency towards more extensive white feather bases compared with the nominate subspecies. But only on the Faroes, a mutation in the melanin metabolism would become fixed in the population, causing some birds to have about half of their feathers entirely white. While albinotic specimens sometimes occur in bird populations, the Pied Raven seems not to have been based on such occasional "sports", but on a constantly or at least regularly present part of the local raven population.
As these birds freely interacted and interbred with the black ones which are still found on the islands, they did not constitute a distinct subspecies. However, they illustrate two aspects of population genetics: genetic drift, which in small populations will shift allele frequencies over time (in this case, causing the occasionally occurring mutation to spread and become a permanent part of the gene pool of ravens on the Faroes), and how a new, distinct subspecies may evolve over time from a distinct part of the population. Had the black and pied ravens mated preferentially with their own morph, in time the pied part of the population might have prevailed, as its coloration probably would have provided better camouflage when preying on seabirds (most of which are also black-and-white).
The first record of the Pied Raven seems to be in the pre-1500 kvæði Fuglakvæði eldra ("The elder ballad of birds") which mentions 40 local species, including the Great Auk. Later, the Pied Raven is mentioned in the reports of Lucas Debes (1673) and Jens Christian Svabo (1781/82). Carl Julian von Graba in 1828 speaks of ten individuals he saw himself and states that these birds, while less numerous than the black morph, were quite common.
Díðrikur á Skarvanesi, the first Faroe painter, painted the Fuglar series, a number of portrayal of birds. On his 18 fuglar ("18 birds"), the animal in the lower right corner can be identified as a Pied Raven. The painting is currently on display in the Listaskálin museum of Faroe art in Tórshavn.
As exemplified by Skarvanesi's painting, which obviously was done from stuffed birds, the Pied Raven was an object of interest to collectors. During the nineteenth century, the pied birds were selectively shot because they could fetch high prices; the sýslumaður (sheriff) of Streymoy, Hans Christopher Müller once paid two Danish rigsdaler for a stuffed specimen from Nólsoy. Such sums, a healthy amount of money for the impoverished Faroe farmers, made shooting a Pied Raven a profitable enterprise. Additionally, ravens in general were hunted as pests. In the mid nineteenth century, every Faroe male of hunting age was ordered by royal decree to shoot at least one raven or two other predatory birds per year or be fined four skillings. One of the last Pied Raven specimens was shot on November 2, 1902 on Mykines. In the autumn of 1916, another bird was seen at Velbastaður and on Koltur. The last known individual was found in the winter of 1947 on Nólsoy, and disappeared late in 1948. As these last sightings raised widespread interest, it seems probable that after 1948, no Pied Raven has been seen.
The Pied Raven, being a colour variation, only differed in one or very few alleles (as opposed to numerous genes in a true subspecies) from the black birds. The "piebald" allele(s) was or were recessive or (if more than one) only caused the novel coloration if they were all present. This is evidenced by the last sightings which occurred in the absence of a regular breeding population of piebald birds, and the observations of H. C. Müller. Thus, it is not certain that the form is indeed extinct, if one can speak of "extinction" in any but a population genetical sense anyway. Theoretically, the allele(s) could still be present but hidden in black individuals of the subspecies and thus, a Pied Raven could once again be born one day. As the raven population on the Faroes has declined to a few hundred birds at best over the recent decades, this does not seem very likely.
Today, 16 museum specimens of the Pied Raven are known: Six in Copenhagen (Zoologisk Museum), four in New York, two in Uppsala, one in Leiden, one in Braunschweig (Naturhistorisches Museum), one in Dresden and one in the Manchester Museum. On June 12, 1995, the Postverk Føroya issued the postal stamp FR 276, which featured a Pied Raven. It was designed by the famous Faroese artist and scientific illustrator Astrid Andreasen.
- Nomenclature of morphs - variants and forms - is unregulated by the ICZN. Arguably, the Pied Raven could be considered a f. loc. (local form)
- von Droste, F. B. (1869). "Vogelfauna der Färöer". Journal für Ornithologie (in German) 17 (2): 107. doi:10.1007/BF02261546.
- Droste, Ferdinand Baron von (1869). "Vogelfauna der Färöer (Färöernes Fuglefauna af Sysselmaand Müller 1862.) Aus dem Dänischen übersetzt und mit Anmerkungen versehen. Teil 1". J. Ornithol. (in German) 17 (2): 107–118. doi:10.1007/BF02261546.
- Corvus albicollis – White-necked Raven
- Corvus corax – Common Raven
- Corvus coronoides – Australian Raven
- Corvus crassirostris – Thick-billed Raven
- Corvus cryptoleucus – Chihuahuan Raven
- Corvus mellori – Little Raven
- Corvus rhipidurus – Fan-tailed Raven
- Corvus ruficollis – Brown-necked Raven
- Corvus tasmanicus – Forest Raven
Crows are highly inteligent birds of the Corvidae family. A flock of crows is called a murder. They have the ability to remember a face. This information soon goes through the entire murder until every single member knows. They can also spot a face in a crowd. This information stays with them for 2 years. But the natural talent dosent stop there. They also understand that it is better to unite and fight a predator than it is to be single and fight a predator.Some belive that crows have a language that is fully developed but there are only a few ornithologists are studying it at all times.
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