Carrion crow

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Carrion crow
Temporal range: Late Pleistocene–Recent
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Corvus corone -near Canford Cliffs, Poole, England-8.jpg
Scavenging on a beach in Dorset, England
Bird recorded in Devon, England
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Corvidae
Genus: Corvus
Species:
C. corone
Binomial name
Corvus corone
Subspecies
Carrion Crow ebird data map.png
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.

Contents

Taxonomy and systematics

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.

Description

Adult male carrion crow moulting at the Jardin des Plantes of Paris Corvus corone Bob 20190916 t170115.jpg
Adult male carrion crow moulting at the Jardin des Plantes of Paris

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.

Distribution and genetic relationship to hooded crows

A map of Europe indicating the distribution of the carrion and hooded crows on either side of a contact zone (white line) separating the two species Distribution of carrion and hooded crows across Europe.jpg
A map of Europe indicating the distribution of the carrion and hooded crows on either side of a contact zone (white line) separating the two species

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]

Behaviour and ecology

In Southend-on-Sea, England Corvus corone -Southend-on-Sea -England-8.jpg
In Southend-on-Sea, England
In flight Carrion crow in flight.jpg
In flight

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]

Intelligence

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]

Diet

Scavenging around a dead bird in Paris, France Corvus corone -Paris, France -several scavenging-8.jpg
Scavenging around a dead bird in Paris, France

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.

Nesting

Eggs, Collection Museum Wiesbaden Corvus corone cornix MWNH 2320.JPG
Eggs, Collection Museum Wiesbaden

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]

Chicks in the nest Carrion Crow Nest 16-05-10 (4612125729).jpg
Chicks in the nest

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]

Related Research Articles

<span class="mw-page-title-main">Corvidae</span> Family of perching birds

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.

<span class="mw-page-title-main">Hooded crow</span> Species of bird

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.

<span class="mw-page-title-main">Australian raven</span> Passerine bird native to Australia

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.

<span class="mw-page-title-main">Torresian crow</span> Species of bird

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.

<span class="mw-page-title-main">Forest raven</span> Australian native bird

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.

<span class="mw-page-title-main">Pied crow</span> Species of bird

The pied crow is a widely distributed African bird species in the crow genus of the family Corvidae.

<span class="mw-page-title-main">Western jackdaw</span> Species of bird in the crow 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.

<span class="mw-page-title-main">American crow</span> Species of 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.

<span class="mw-page-title-main">Daurian jackdaw</span> Species of bird of the genus Coloeus

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.

<span class="mw-page-title-main">Collared crow</span> Species of bird

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.

<span class="mw-page-title-main">Fan-tailed raven</span> Species of bird

The fan-tailed raven is a passerine bird of the crow family native to Eastern Africa and the Arabian Peninsula.

<span class="mw-page-title-main">Brown-necked raven</span> Species of bird

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.

<span class="mw-page-title-main">Large-billed crow</span> Species of bird

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.

<span class="mw-page-title-main">Common raven</span> Large, black, passerine bird of the Northern Hemisphere

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.

<span class="mw-page-title-main">Crow</span> Index of animals with the same common name

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.

<i>Corvus</i> Genus of birds including crows, ravens and rooks

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".

<span class="mw-page-title-main">Koinophilia</span> Hypothesis on normative mate selection

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".

<span class="mw-page-title-main">Chihuahuan raven</span> Species of bird

The Chihuahuan raven is a species of crow in the family Corvidae that is native to the United States and Mexico.

<span class="mw-page-title-main">Rook (bird)</span> Species of bird in the crow family Corvidae

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.

<span class="mw-page-title-main">Somali crow</span> Species of bird

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.

References

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  9. Attenborough. D. 1998. The Life of Birds. pp.295 BBC ISBN   0563-38792-0
  10. "Differences Between Crows, Ravens and Rooks – With Photos". animalwised.com. Retrieved 24 January 2022.
  11. "British Garden Birds – Carrion Crow". garden-birds.co.uk. Retrieved 24 January 2022.
  12. Holden, Peter (2012). RSPB Handbook of British Birds. Christopher Helm. p. 274. ISBN   978-1-4081-2735-3.
  13. Pettifor, R. A (1990). "The effects of avian mobbing on a potential predator, the European kestrel, Falco tinnunculus". Animal Behaviour. 39 (5): 821–827. doi:10.1016/S0003-3472(05)80945-5. S2CID   53200478.
  14. 1 2 Nieder A.; et al. (2017). "Inside the corvid brain—probing the physiology of cognition in crows". Current Opinion in Behavioral Sciences. 16 (8): 8–14. doi:10.1016/j.cobeha.2017.02.005. S2CID   44291562.
  15. Ditz, Helen; Nieder, Andreas (2016). "Numerosity representations in crows obey the Weber–Fechner law". Proceedings of the Royal Society B: Biological Sciences. 283 (1827): 20160083. doi:10.1098/rspb.2016.0083. PMC   4822466 . PMID   27009227.
  16. Andreas Nieder; Veit, Lena (28 November 2013). "Abstract rule neurons in the endbrain support intelligent behaviour in corvid songbirds". Nature Communications. 4: 2878. Bibcode:2013NatCo...4.2878V. doi: 10.1038/ncomms3878 . ISSN   2041-1723. PMID   24285080.
  17. Brecht, Katharina F.; Wagener, Lysann; Ostojić, Ljerka; Clayton, Nicola S.; Nieder, Andreas (1 December 2017). "Comparing the face inversion effect in crows and humans". Journal of Comparative Physiology A. 203 (12): 1017–1027. doi:10.1007/s00359-017-1211-7. ISSN   1432-1351. PMC   5696503 . PMID   28905251.
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  19. British Trust for Ornithology (2005) Nest Record Scheme data.
  20. Baglione, V.; Marcos, J. M.; Canestrari, D.; Ekman, J. (2002). "Direct fitness benefits of group living in a complex cooperative society of carrion crows, Corvus corone corone". Animal Behaviour. 64 (6): 887–893. doi:10.1006/anbe.2002.2007. S2CID   53200940.