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Carrion crow Temporal range: | |
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Scavenging on a beach in Dorset, England | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Aves |
Order: | Passeriformes |
Family: | Corvidae |
Genus: | Corvus |
Species: | C. corone |
Binomial name | |
Corvus corone | |
Subspecies | |
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Carrion crow range Year-round range Summer range Winter range |
The carrion crow (Corvus corone) is a passerine bird of the family Corvidae, native to western Europe and the eastern Palearctic.
The carrion crow was one of the many species originally described by Carl Linnaeus in his landmark 1758 10th edition of Systema Naturae, and it still bears its original name of Corvus corone. [2] The binomial name is derived from the Latin corvus, "raven", [3] and Greek κορώνηkorōnē, "crow". [4]
The hooded crow (Corvus cornix), formerly regarded as a subspecies, has been split off as a separate species, and there is some discussion whether the eastern carrion crow (C. c. orientalis) is distinct enough to warrant specific status; the two taxa are well separated, and it has been proposed they could have evolved independently in the wetter, maritime regions at the opposite ends of the Eurasian landmass. [5]
Along with the hooded crow, the carrion crow occupies a similar ecological niche in Eurasia to the American crow (Corvus brachyrhynchos) in North America. The two species look very similar to one another, but can be differentiated by size, as the carrion crow is larger and of a stockier build compared to the American crow.
The plumage of the carrion crow is black with a green or purple sheen, much greener than the gloss of the rook (Corvus frugilegus). The bill, legs and feet are also black. It can be distinguished from the common raven by its size of around 48–52 centimetres (19–20 in) in length as compared to an average of 63 centimetres (25 inches) for ravens, and from the hooded crow by its black plumage. The carrion crow has a wingspan of 84–100 centimetres (33–39 in) and weighs 400–600 grams (14 oz – 1 lb 5 oz).
Juvenile carrion crows can be identified by their brownish plumage and blue eyes, both of which darken to black and brown as the crow grows older.
The carrion crow (Corvus corone) and hooded crow (Corvus cornix), including the former's slightly larger allied form or race C. c. orientalis, are two very closely related species; [6] the geographic distributions of both forms of carrion crow across Europe are illustrated in the accompanying diagram. It is believed that this distribution might have resulted from the glaciation cycles during the Pleistocene, which caused the parent population to split into isolates which subsequently re-expanded their ranges when the climate warmed causing secondary contact. [7] [8]
Poelstra and coworkers sequenced almost the entire genomes of both species in populations at varying distances from the contact zone to find that the two species were genetically identical, both in their DNA and in its expression (in the form of mRNA), except for the lack of expression of a small portion (<0.28%) of the genome (situated on avian chromosome 18) in the hooded crow, which imparts the lighter plumage colouration on its torso. [7] Thus the two species can viably hybridize, and occasionally do so at the contact zone, but the all-black carrion crows on the one side of the contact zone mate almost exclusively with other all-black carrion crows, while the same occurs among the hooded crows on the other side of the contact zone.
It is therefore clear that it is only the outward appearance of the two species that inhibits hybridization. [7] [8] The authors attribute this to assortative mating (rather than to ecological selection), the advantage of which is not clear, and it would lead to the rapid appearance of streams of new lineages, and possibly even species, through mutual attraction between mutants. Unnikrishnan and Akhila propose, instead, that koinophilia is a more parsimonious explanation for the resistance to hybridization across the contact zone, despite the absence of physiological, anatomical or genetic barriers to such hybridization. [7] The carrion crow is also found in the mountains and forests of Japan and also in the cities of Japan. [9]
The rook is generally gregarious and the crow largely solitary, but rooks occasionally nest in isolated trees, and crows may feed with rooks; moreover, crows are often sociable in winter roosts. The most distinctive feature is the voice. The rook has a high-pitched kaaa, but the crow's guttural, slightly vibrant, deeper croaked kraa is distinct from any note of the rook. [10]
The carrion crow is noisy, perching on a vantage point such as a building or the top of a tree and calling three or four times in quick succession, with a slight pause between each series of croaks. During each series of calls, a crow may perform an accompanying gesture, raising its shoulders and bowing its head and neck downwards with each caw. The wing-beats are slower, more deliberate than those of the rook. [11]
Carrion crows can become tame near humans, and can often be found near areas of human activity or habitation including cities, moors, woodland, sea cliffs and farmland [12] where they compete with other social birds such as gulls, other corvids, and ducks for food in parks and gardens.
Like other species of corvid, carrion crows will actively harass predators and competitors that enter their territory or threaten them or their offspring, and will engage in group mobbing behaviour as a method to defend themselves. [13]
Like all corvids, carrion crows are very intelligent. [14] For example, they can discriminate between numerosities up to 30, [15] flexibly switch between rules, [16] and recognise human and crow faces. [17] Given the difference in brain architecture in crows compared to primates, these abilities suggest that their intelligence is realised as a product of convergent evolution. [14]
Though an eater of carrion of all kinds, the carrion crow will eat insects, earthworms, other invertebrates, [18] grain, fruits, seeds, nuts, [18] small mammals, amphibians, fish, [18] scraps and will also steal eggs. Crows are scavengers by nature, which is why they tend to frequent sites inhabited by humans in order to feed on their household waste. Crows will also harass birds of prey or even foxes for their kills. Crows actively hunt and occasionally co-operate with other crows to make kills, and are sometimes seen catching ducklings for food. Due to their gregarious lifestyle and defensive abilities, carrion crows have few natural predators. However, powerful raptors such as the Eurasian goshawk, peregrine falcon, Eurasian eagle-owl and golden eagle will readily hunt them, and crows can become an important prey item locally.
The bulky stick nest is usually placed in a tall tree, but cliff ledges, old buildings and pylons may be used as well. Nests are also occasionally placed on or near the ground. The nest resembles that of the common raven, but is less bulky. The 3 to 4 brown-speckled blue or greenish eggs are incubated for 18–20 days by the female alone, who is fed by the male. The young fledge after 29–30 days. [19]
It is not uncommon for an offspring from the previous years to stay around and help rear the new hatchlings. Instead of seeking out a mate, it looks for food and assists the parents in feeding the young. [20]
Corvidae is a cosmopolitan family of oscine passerine birds that contains the crows, ravens, rooks, magpies, jackdaws, jays, treepies, choughs, and nutcrackers. In colloquial English, they are known as the crow family or corvids. Currently, 139 species are included in this family. The genus Corvus containing 50 species makes up over a third of the entire family. Corvids (ravens) are the largest passerines.
The hooded crow, also called the scald-crow or hoodie, is a Eurasian bird species in the genus Corvus. Widely distributed, it is found across Northern, Eastern, and Southeastern Europe, as well as parts of the Middle East. It is an ashy grey bird with black head, throat, wings, tail, and thigh feathers, as well as a black bill, eyes, and feet. Like other corvids, it is an omnivorous and opportunistic forager and feeder.
The Australian raven is a passerine corvid bird native to Australia. Measuring 46–53 centimetres (18–21 in) in length, it has an all-black plumage, beak and mouth, as well as strong, greyish-black legs and feet. The upperparts of its body are glossy, with a purple-blue, greenish sheen; its black feathers have grey bases. The Australian raven is distinguished from the Australian crow, and other related corvids, by its long chest feathers, or throat hackles, which are prominent in mature birds. Older individuals and subadults have white irises, while the younger birds' eyes display blue inner rims; hatchlings and young birds have brown, dark irises until about fifteen months of age, at which point their irises become hazel-coloured, with an inner blue rim around each pupil, this lasting until they are roughly 2.5 to 3 years of age. Nicholas Aylward Vigors and Thomas Horsfield described the Australian raven in 1827, its species name coronoides highlighting its similarity with the carrion crow. Two subspecies are recognised, which differ slightly in their vocalisations, and are quite divergent, genetically.
The Torresian crow, also called the Australian crow or Papuan crow, is a passerine bird in the crow family native to the north and west of Australia and nearby islands in Indonesia and Papua New Guinea. The species has a black plumage, beak and mouth with white irises. The base of the feathers on the head and neck are white. The Torresian crow is slightly larger with a more robust bill than the morphologically similar little crow.
The forest raven, also commonly known as the Tasmanian raven, is a passerine bird in the family Corvidae native to Tasmania and parts of southern Victoria, such as Wilsons Promontory and Portland. Populations are also found in parts of New South Wales, including Dorrigo and Armidale. Measuring 50–53 cm (20–21 in) in length, it has all-black plumage, beak and legs. As with the other two species of raven in Australia, its black feathers have grey bases. Adults have white irises; younger birds have dark brown and then hazel irises with an inner blue rim. New South Wales populations are recognised as a separate subspecies C. tasmanicus boreus, but appear to be nested within the Tasmanian subspecies genetically.
The pied crow is a widely distributed African bird species in the crow genus of the family Corvidae.
The western jackdaw, also known as the Eurasian jackdaw, the European jackdaw, or simply the jackdaw, is a passerine bird in the crow family. Found across Europe, western Asia and North Africa; it is mostly resident, although northern and eastern populations migrate south in the winter. Four subspecies are recognised, which differ mainly in the colouration of the plumage on the head and nape. Linnaeus first described it formally, giving it the name Corvus monedula. The common name derives from the word jack, denoting "small", and daw, a less common synonym for "jackdaw", and the native English name for the bird.
The American crow is a large passerine bird species of the family Corvidae. It is a common bird found throughout much of North America. American crows are the New World counterpart to the carrion crow and the hooded crow of Eurasia; they all occupy the same ecological niche. Although the American crow and the hooded crow are very similar in size, structure and behavior, their calls and visual appearance are different.
The Daurian jackdaw is a bird in the crow family, Corvidae, native to eastern Asia. It is closely related to the western jackdaw. The name derives from the Dauria region of eastern Russia.
The collared crow, also known as the ring-necked crow or white-collared crow, is a member of the family Corvidae native to China and north of Vietnam.
The fan-tailed raven is a passerine bird of the crow family native to Eastern Africa and the Arabian Peninsula.
The brown-necked raven is a larger bird than the carrion crow though not as large as the common raven. It has similar proportions to the common raven but the bill is not so large or deep and the wings tend to be a little more pointed in profile. The head and throat are a distinct brownish-black giving the bird its English name, while the rest of the plumage is black glossed with purple, blue or purplish-blue. Like the common raven, thick-billed raven and white-necked raven, it is one of the larger raven species. The feathers of this species often fade quite quickly to a brownish black and the bird can look distinctly brown by the time it moults. The feet, legs and bill are black. The dwarf raven was formerly considered a subspecies but this bird now appears to be closer to the pied crow than this species.
The large-billed crow, formerly referred to widely as the jungle crow, is a widespread Asian species of crow. It is very adaptable and is able to survive on a wide range of food sources, making it capable of colonizing new areas, due to which it is often considered a nuisance, especially on islands. It has a large bill, which is the source of its scientific name macrorhynchos and it is sometimes known by the common name thick-billed crow. It can also be mistaken for a common raven. The eastern jungle crow and Indian jungle crow were once considered conspecific and together called the jungle crow.
The common raven is a large all-black passerine bird. It is the most widely distributed of all corvids, found across the Northern Hemisphere. It is a raven known by many names at the subspecies level; there are at least eight subspecies with little variation in appearance, although recent research has demonstrated significant genetic differences among populations from various regions. It is one of the two largest corvids, alongside the thick-billed raven, and is possibly the heaviest passerine bird; at maturity, the common raven averages 63 centimetres in length and 1.47 kilograms in mass. Although their typical lifespan is considerably shorter, common ravens can live more than 23 years in the wild. Young birds may travel in flocks but later mate for life, with each mated pair defending a territory.
A crow is a bird of the genus Corvus, or more broadly, a synonym for all of Corvus. The word "crow" is used as part of the common name of many species. The related term "raven" is not linked scientifically to any certain trait but is rather a general grouping for larger-sized species of Corvus.
Corvus is a widely distributed genus of passerine birds ranging from medium-sized to large-sized in the family Corvidae. It includes species commonly known as crows, ravens, and rooks. The species commonly encountered in Europe are the carrion crow, hooded crow, common raven, and rook; those discovered later were named "crow" or "raven" chiefly on the basis of their size, crows generally being smaller. The genus name is Latin for "raven".
Koinophilia is an evolutionary hypothesis proposing that during sexual selection, animals preferentially seek mates with a minimum of unusual or mutant features, including functionality, appearance and behavior. Koinophilia intends to explain the clustering of sexual organisms into species and other issues described by Darwin's dilemma. The term derives from the Greek word koinos meaning "common" or "that which is shared", and philia, meaning "fondness".
The Chihuahuan raven is a species of crow in the family Corvidae that is native to the United States and Mexico.
The rook is a member of the family Corvidae in the passerine order of birds. It is found in the Palearctic, its range extending from Scandinavia and western Europe to eastern Siberia. It is a large, gregarious, black-feathered bird, distinguished from similar species by the whitish featherless area on the face. Rooks nest collectively in the tops of tall trees, often close to farms or villages; the groups of nests are known as rookeries.
The Somali crow, or dwarf raven, is approximately the size of the carrion crow, Corvus corone but with a longer bill and a somewhat more brownish cast to the feathers, especially when worn.
C. atro-caerulescens, cauda rotundata: rectricibus acutis.