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The common raven (''Corvus corax'') is a large all-black passerine bird. It is the most widely distributed of all corvids, found across the
Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's Nort ...
. It is a
raven A raven is any of several larger-bodied bird species of the genus ''Corvus''. These species do not form a single taxonomic group within the genus. There is no consistent distinction between "crows" and "ravens", common names which are assigned t ...
known by many names at the subspecies level; there are at least eight
subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...
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 in length and 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 In biology, a pair bond is the strong affinity that develops in some species between a mating pair, often leading to the production and rearing of offspring and potentially a lifelong bond. Pair-bonding is a term coined in the 1940s that is freque ...
, with each mated pair defending a territory. Common ravens have coexisted with humans for thousands of years and in some areas have been so numerous that people have regarded them as
pests PESTS was an anonymous American activist group formed in 1986 to critique racism, tokenism, and exclusion in the art world. PESTS produced newsletters, posters, and other print material highlighting examples of discrimination in gallery represent ...
. Part of their success as a species is due to their omnivorous diet; they are extremely versatile and opportunistic in finding sources of nutrition, feeding on
carrion Carrion () is the decaying flesh of dead animals, including human flesh. Overview Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters (or scavengers) include crows, vultures, c ...
, insects, cereal grains, berries, fruit, small animals, nesting birds, and food waste. Some notable feats of problem-solving provide evidence that the common raven is unusually intelligent. Over the centuries, the raven has been the subject of mythology, folklore, art, and literature. In many cultures, including the indigenous cultures of Scandinavia, ancient Ireland and Wales,
Bhutan Bhutan (; dz, འབྲུག་ཡུལ་, Druk Yul ), officially the Kingdom of Bhutan,), is a landlocked country in South Asia. It is situated in the Eastern Himalayas, between China in the north and India in the south. A mountai ...
, the northwest coast of North America, and Siberia and northeast Asia, the common raven has been revered as a spiritual figure or godlike creature.


Taxonomy

The common raven was one of the many species originally described, with its
type locality Type locality may refer to: * Type locality (biology) * Type locality (geology) See also * Local (disambiguation) * Locality (disambiguation) {{disambiguation ...
given as Europe, by
Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, ...
in his landmark 1758 10th edition of ''Systema Naturae'', and it still bears its original name of ''Corvus corax''. It is the type species of the genus '' Corvus'', derived from the
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power ...
word for 'raven'. The specific epithet ''corax'' is the Latinized form of the Greek word , meaning 'raven' or 'crow'.. The modern English word ''raven'' has cognates in many other
Germanic languages The Germanic languages are a branch of the Indo-European language family spoken natively by a population of about 515 million people mainly in Europe, North America, Oceania and Southern Africa. The most widely spoken Germanic language, ...
, including Old Norse (and subsequently
modern Icelandic Icelandic (; is, íslenska, link=no ) is a North Germanic language spoken by about 314,000 people, the vast majority of whom live in Iceland, where it is the national language. Due to being a West Scandinavian language, it is most closely re ...
) and Old High German , all which descend from Proto-Germanic . An old
Scottish Scottish usually refers to something of, from, or related to Scotland, including: *Scottish Gaelic, a Celtic Goidelic language of the Indo-European language family native to Scotland *Scottish English *Scottish national identity, the Scottish ide ...
word or , akin to the French , has been used for both this bird and the carrion crow. Collective nouns for a group of ravens (or at least the common raven) include "unkindness" and "conspiracy".


Classification

The closest relatives of the common raven are the brown-necked raven (''C. ruficollis''), the pied crow (''C. albus'') of Africa, and the Chihuahuan raven (''C. cryptoleucus'') of the North American Southwest. While some authorities have recognized as many as 11
subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...
,Marzluff, J. M. (2009). "Common Raven (''Corvus corax'')". pp. 638–639 in ''
Handbook of the Birds of the World The ''Handbook of the Birds of the World'' (HBW) is a multi-volume series produced by the Spanish publishing house Lynx Edicions in partnership with BirdLife International. It is the first handbook to cover every known living species of bird. T ...
.'' Bush-shrikes to Old World Sparrows. del Hoyo, J., Elliott, A. and Christie, D. A. (eds.). Lynx Edicions, Barcelona.
others recognize only eight:Clements, J. F. (2007). ''The Clements Checklist of the Birds of the World.'' 6th edition. Christopher Helm.


Evolutionary history

The common raven evolved in the
Old World The "Old World" is a term for Afro-Eurasia that originated in Europe , after Europeans became aware of the existence of the Americas. It is used to contrast the continents of Africa, Europe, and Asia, which were previously thought of by the ...
and crossed the Bering land bridge into North America. Recent genetic studies, which examined the DNA of common ravens from across the world, have determined that the birds fall into at least two
clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term ...
s: a
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the ...
clade, found only in the southwestern United States, and a Holarctic clade, found across the rest of the Northern Hemisphere. Birds from both clades look alike, but the groups are genetically distinct and began to diverge about two million years ago. The findings indicate that based on
mitochondrial DNA Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial D ...
, common ravens from the rest of the United States are more closely related to those in Europe and Asia than to those in the California clade, and that common ravens in the California clade are more closely related to the Chihuahuan raven (''C. cryptoleucus'') than to those in the Holarctic clade. Ravens in the Holarctic clade are more closely related to the pied crow (''C. albus'') than they are to the California clade. Thus, the common raven species as traditionally delimited is considered to be
paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...
. One explanation for these genetic findings is that common ravens settled in California at least two million years ago and became separated from their relatives in Europe and Asia during a glacial period. One million years ago, a group from the California clade evolved into a new species, the Chihuahuan raven. Other members of the Holarctic clade arrived later in a separate migration from Asia, perhaps at the same time as humans. A 2011 study suggested that there are no restrictions on
gene flow In population genetics, gene flow (also known as gene migration or geneflow and allele flow) is the transfer of genetic material from one population to another. If the rate of gene flow is high enough, then two populations will have equivalent a ...
between the Californian and Holarctic common raven groups, and that the lineages can remerge, effectively reversing a potential speciation. A recent study of raven mitochondrial DNA showed that the isolated population from the
Canary Islands The Canary Islands (; es, Canarias, ), also known informally as the Canaries, are a Spanish autonomous community and archipelago in the Atlantic Ocean, in Macaronesia. At their closest point to the African mainland, they are west of Morocc ...
is distinct from other populations. The study did not include any individuals from the North African population, and its position is therefore unclear, though its morphology is very close to the population of the Canaries (to the extent that the two are often considered part of a single subspecies).


Description

A mature common raven ranges between 54 and 67 cm (21" and 26") long, with a wingspan of 115 to 150 cm (45–51"). Recorded weights range from 0.69 to 2 kg (1.5 to 4.4 lb), thus making the common raven one of the heaviest passerines. Birds from colder regions such as the
Himalayas The Himalayas, or Himalaya (; ; ), is a mountain range in Asia, separating the plains of the Indian subcontinent from the Tibetan Plateau. The range has some of the planet's highest peaks, including the very highest, Mount Everest. Over ...
and Greenland are generally larger with slightly larger bills, while those from warmer regions are smaller with proportionally smaller bills. Representative of the size variation in the species, ravens from
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the ...
weighed an average of , those from
Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S ...
weighed an average of and those from Nova Scotia weighed an average of . The bill is large and slightly curved, with a culmen length of , easily one of the largest bills amongst passerines (perhaps only the thick-billed raven has a noticeably larger bill). It has a longish, strongly graduated tail, at , and mostly black
iridescent Iridescence (also known as goniochromism) is the phenomenon of certain surfaces that appear to gradually change color as the angle of view or the angle of illumination changes. Examples of iridescence include soap bubbles, feathers, butterfl ...
plumage, and a dark brown iris. The throat feathers are elongated and pointed and the bases of the neck feathers are pale brownish-grey. The legs and feet are good-sized, with a tarsus length of . Juvenile plumage is similar but duller with a blue-grey iris. Apart from its greater size, the common raven differs from its cousins, the crows, by having a larger and heavier black beak, shaggy feathers around the throat and above the beak, and a wedge-shaped tail. Flying ravens are distinguished from crows by their tail shape, larger wing area, and more stable soaring style, which generally involves less wing flapping. Despite their bulk, ravens are easily as agile in flight as their smaller cousins. In flight the feathers produce a creaking sound that has been likened to the rustle of silk. The voice of ravens is also quite distinct, its usual call being a deep croak of a much more sonorous quality than a crow's call. In North America, the Chihuahuan raven (''C. cryptoleucus'') is fairly similar to the relatively small common ravens of the American southwest and is best distinguished by the still relatively smaller size of its bill, beard and body and relatively longer tail. All-black carrion crow (''C. corone'') in Europe may suggest a raven due to their largish bill but are still distinctly smaller and have the wing and tail shapes typical of crows. In the
Faroe Islands The Faroe Islands ( ), or simply the Faroes ( fo, Føroyar ; da, Færøerne ), are a North Atlantic archipelago, island group and an autonomous territory of the Danish Realm, Kingdom of Denmark. They are located north-northwest of Scotlan ...
, a now-extinct white-and-black colour morph of this species existed, known as the pied raven. White ravens are occasionally found in the wild. Birds in
British Columbia British Columbia (commonly abbreviated as BC) is the westernmost Provinces and territories of Canada, province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include ...
lack the pink eyes of an albino, and are instead leucistic, a condition where an animal lacks any of several different types of pigment, not simply melanin. Common ravens have a wide range of vocalizations which are of interest to
ornithologist Ornithology is a branch of zoology that concerns the "methodological study and consequent knowledge of birds with all that relates to them." Several aspects of ornithology differ from related disciplines, due partly to the high visibility and th ...
s. Gwinner carried out important studies in the early 1960s, recording and photographing his findings in great detail. Fifteen to 30 categories of vocalization have been recorded for this species, most of which are used for social interaction. Calls recorded include alarm calls, chase calls, and flight calls. The species has a distinctive, deep, resonant ''prruk-prruk-prruk'' call, which to experienced listeners is unlike that of any other corvid. Its very wide and complex vocabulary includes a high, knocking ''toc-toc-toc'', a dry, grating ''kraa'', a low guttural rattle and some calls of an almost musical nature. Like other corvids, the common raven can mimic sounds from their environment, including human speech. Non-vocal sounds produced by the common raven include wing whistles and bill snapping. Clapping or clicking has been observed more often in females than in males. If a member of a pair is lost, its mate reproduces the calls of its lost partner to encourage its return.


Distribution and habitat

The common raven can thrive in varied climates; indeed this species has the largest range of any member of the genus, and one of the largest of any passerine. They range throughout the Holarctic from Arctic and temperate habitats in North America and Eurasia to the deserts of North Africa, and to islands in the Pacific Ocean. In the British Isles, they are more common in Scotland, Wales, northern England and the west of Ireland. In Tibet, they have been recorded at altitudes up to 5,000 m (16,400 ft), and as high as 6,350 m (20,600 ft) on
Mount Everest Mount Everest (; Tibetan: ''Chomolungma'' ; ) is Earth's highest mountain above sea level, located in the Mahalangur Himal sub-range of the Himalayas. The China–Nepal border runs across its summit point. Its elevation (snow ...
. The population sometimes known as the Punjab raven—described as ''Corvus corax laurencei'' (also spelt ''lawrencii'' or ''laurencii'') by Allan Octavian Hume but more often considered synonymous with ''subcorax''—is restricted to the
Sindh Sindh (; ; ur, , ; historically romanized as Sind) is one of the four provinces of Pakistan. Located in the southeastern region of the country, Sindh is the third-largest province of Pakistan by land area and the second-largest province ...
district of Pakistan and adjoining regions of northwestern India. They are generally resident within their range for the whole year. In his 1950 work, ''Grønlands Fugle'' 'Birds of Greenland'' noted ornithologist Finn Salomonsen indicated that common ravens did not overwinter in the Arctic. However, in Arctic Canada and Alaska, they are found year-round. Young birds may disperse locally. Goodwin, p. 139 In the United Kingdom, the common raven's range has been increasing, though it favours mountainous or coastal terrain, but can also be found in parks with tall trees suitable for use as habitation. Its population is at its most dense in the north and west of the country, though the species is expanding its population southwards. Most common ravens prefer wooded areas with large expanses of open land nearby, or coastal regions for their nesting sites and feeding grounds. In some areas of dense human population, such as
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the ...
in the United States, they take advantage of a plentiful food supply and have seen a surge in their numbers. On coasts, individuals of this species are often evenly distributed and prefer to build their nest sites along sea cliffs. Common ravens are often located in coastal regions because these areas provide easy access to water and a variety of food sources. Also, coastal regions have stable weather patterns without extreme cold or hot temperatures. In general, common ravens live in a wide array of environments but prefer heavily contoured landscapes. When the environment changes in vast degrees, these birds will respond with a stress response. The hormone known as corticosterone is activated by the hypothalamic–pituitary–adrenal axis. Corticosterone is activated when the bird is exposed to stress, such as migrating great distances.


Behaviour

Common ravens usually travel in mated pairs, although young birds may form flocks. Relationships between common ravens are often quarrelsome, yet they demonstrate considerable devotion to their families.


Predation

Owing to its size, gregariousness and its defensive abilities, the common raven has few natural predators. Predators of its eggs include owls,
marten A marten is a weasel-like mammal in the genus ''Martes'' within the subfamily Guloninae, in the family Mustelidae. They have bushy tails and large paws with partially retractile claws. The fur varies from yellowish to dark brown, depending on t ...
s, and sometimes
eagle Eagle is the common name for many large birds of prey of the family Accipitridae. Eagles belong to several groups of genera, some of which are closely related. Most of the 68 species of eagle are from Eurasia and Africa. Outside this area, just ...
s. Ravens are quite vigorous at defending their young and are usually successful at driving off perceived threats. They attack potential predators by flying at them and lunging with their large bills. Humans are occasionally attacked if they get close to a raven nest, though serious injuries are unlikely. There are a few records of predation by large birds of prey. Their attackers in America have reportedly included great horned owls,
northern goshawk The northern goshawk (; ''Accipiter gentilis'') is a species of medium-large bird of prey, raptor in the Family (biology), family Accipitridae, a family which also includes other extant diurnal raptors, such as eagles, buzzards and harrier (bird) ...
s,
bald eagle The bald eagle (''Haliaeetus leucocephalus'') is a bird of prey found in North America. A sea eagle, it has two known subspecies and forms a species pair with the white-tailed eagle (''Haliaeetus albicilla''), which occupies the same niche as ...
s, golden eagles and red-tailed hawks. It is possible that the two hawk species only attack young ravens; in one instance a
peregrine falcon The peregrine falcon (''Falco peregrinus''), also known as the peregrine, and historically as the duck hawk in North America, is a Cosmopolitan distribution, cosmopolitan bird of prey (Bird of prey, raptor) in the family (biology), family Falco ...
swooped at a newly fledged raven but was chased off by the parent ravens. In
Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelag ...
, their reported predators include, in addition to golden eagles, Eurasian eagle-owls, white-tailed eagles,
Steller's sea-eagle Steller's sea eagle (''Haliaeetus pelagicus''), also known as Pacific sea eagle or white-shouldered eagle, is a very large diurnal bird of prey in the family Accipitridae. It was described first by Peter Simon Pallas in 1811. No subspecies are r ...
s, eastern imperial eagles and gyrfalcons. Because they are potentially hazardous prey for raptorial birds, raptors must usually take them by surprise and most attacks are on fledgling ravens. More rarely still, large mammalian predators such as
lynx A lynx is a type of wild cat. Lynx may also refer to: Astronomy * Lynx (constellation) * Lynx (Chinese astronomy) * Lynx X-ray Observatory, a NASA-funded mission concept for a next-generation X-ray space observatory Places Canada * Lynx, Ontar ...
es,
coyote The coyote (''Canis latrans'') is a species of canis, canine native to North America. It is smaller than its close relative, the wolf, and slightly smaller than the closely related eastern wolf and red wolf. It fills much of the same ecologica ...
s and
cougar The cougar (''Puma concolor'') is a large Felidae, cat native to the Americas. Its Species distribution, range spans from the Canadian Yukon to the southern Andes in South America and is the most widespread of any large wild terrestrial mamm ...
s have also attacked ravens. This principally occurs at a nest site and when other prey for the carnivores are scarce. Ravens are highly wary around novel carrion sites and, in North America, have been recorded waiting for the presence of American crows and
blue jay The blue jay (''Cyanocitta cristata'') is a passerine bird in the family Corvidae, native to eastern North America. It lives in most of the eastern and central United States; some eastern populations may be migratory. Resident populations are a ...
s before approaching to eat.


Breeding

Juveniles begin to court at a very early age, but may not bond for another two or three years. Aerial acrobatics, demonstrations of intelligence, and ability to provide food are key behaviours of courting. Once paired, they tend to nest together for life, usually in the same location. Instances of non-monogamy have been observed in common ravens, by males visiting a female's nest when her mate is away. Breeding pairs must have a territory of their own before they begin nest-building and reproduction, and thus they aggressively defend a territory and its food resources. Nesting territories vary in size according to the density of food resources in the area. The nest is a deep bowl made of large sticks and twigs, bound with an inner layer of roots, mud, and bark and lined with a softer material, such as deer fur. The nest is usually placed in a large tree or on a cliff ledge, or less frequently in old buildings or utility poles. Females lay between three and seven pale bluish-green, brown-blotched eggs. Incubation is about 18 to 21 days, by the female only. The male may stand or crouch over the young, sheltering but not actually
brooding Egg incubation is the process by which an egg, of oviparous (egg-laying) animals, develops an embryo within the egg, after the egg's formation and ovipositional release. Egg incubation is done under favorable environmental conditions, possib ...
them. Young
fledge Fledging is the stage in a flying animal's life between hatching or birth and becoming capable of flight. This term is most frequently applied to birds, but is also used for bats. For altricial birds, those that spend more time in vulnerable c ...
at 35 to 42 days, and are fed by both parents. They stay with their parents for another six months after fledging. In most of their range, egg-laying begins in late February. In colder climates, it is later, e.g. April in Greenland and Tibet. In Pakistan, egg-laying takes place in December. Eggs and hatchlings are preyed on, rarely, by large
hawk Hawks are bird of prey, birds of prey of the family Accipitridae. They are widely distributed and are found on all continents except Antarctica. * The subfamily Accipitrinae includes goshawks, sparrowhawks, sharp-shinned hawks and others. Th ...
s and
eagle Eagle is the common name for many large birds of prey of the family Accipitridae. Eagles belong to several groups of genera, some of which are closely related. Most of the 68 species of eagle are from Eurasia and Africa. Outside this area, just ...
s, large owls,
marten A marten is a weasel-like mammal in the genus ''Martes'' within the subfamily Guloninae, in the family Mustelidae. They have bushy tails and large paws with partially retractile claws. The fur varies from yellowish to dark brown, depending on t ...
s and canids. The adults, which are very rarely preyed upon, are often successful in defending their young from these predators, due to their numbers, large size and cunning. They have been observed dropping stones on potential predators that venture close to their nests. Common ravens can be very long-lived, especially in captive or protected conditions; individuals at the Tower of London have lived for more than 40 years. Lifespans in the wild are considerably shorter at typically 10 to 15 years. The longest known lifespan of a banded wild common raven was 23 years, 3 months, which among passerines only is surpassed by a few Australian species such as the satin bowerbird.


Feeding

Common ravens are omnivorous and highly opportunistic: their diet may vary widely with location, season and
serendipity Serendipity is an unplanned fortunate discovery. Serendipity is a common occurrence throughout the history of product invention and scientific discovery. Etymology The first noted use of "serendipity" was by Horace Walpole on 28 January 1754. I ...
. For example, those foraging on tundra on the
Arctic North Slope The Alaska North Slope ( Iñupiaq: ''Siḷaliñiq'') is the region of the U.S. state of Alaska located on the northern slope of the Brooks Range along the coast of two marginal seas of the Arctic Ocean, the Chukchi Sea being on the western sid ...
of
Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S ...
obtained about half their energy needs from predation, mainly of microtine rodents, and half by scavenging, mainly of
caribou Reindeer (in North American English, known as caribou if wild and ''reindeer'' if domesticated) are deer in the genus ''Rangifer''. For the last few decades, reindeer were assigned to one species, ''Rangifer tarandus'', with about 10 subspe ...
and ptarmigan carcasses. In some places they are mainly
scavenger Scavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a herbivorous feeding b ...
s, feeding on
carrion Carrion () is the decaying flesh of dead animals, including human flesh. Overview Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters (or scavengers) include crows, vultures, c ...
as well as the associated maggots and carrion beetles. With large-bodied carrion, which they are not equipped to tear through as well as birds such as hook-billed vultures, they must wait for the prey to be torn open by another predator or flayed by other means. They are also known to eat the afterbirth of ewes and other large mammals. Plant food includes cereal grains, acorns, buds, berries and fruit. They prey on small invertebrates, amphibians, reptiles, small mammals and birds. Ravens may also consume the undigested portions of animal feces, and human food waste. They store surplus food items, especially those containing fat, and will learn to hide such food out of the sight of other common ravens. Ravens also raid the food caches of other species, such as the Arctic fox. They sometimes associate with another canine, the grey wolf, as a kleptoparasite, following to scavenge wolf-kills in winter. Ravens are regular predators at bird nests, brazenly picking off eggs, nestlings and sometimes adult birds when they spot an opportunity. They are considered perhaps the primary natural threat to the nesting success of the critically endangered California condor, since they readily take condor eggs and are very common in the areas where the species is being re-introduced. On the other hand, when they defend their own adjacent nests, they may incidentally benefit condors since they chase golden eagles out of the area that may otherwise prey upon larger nestling and fledging condors. Condors, despite their large size, do not seem to have well developed nest defenses. Common ravens nesting near sources of human
garbage Garbage, trash, rubbish, or refuse is waste material that is discarded by humans, usually due to a perceived lack of utility. The term generally does not encompass bodily waste products, purely liquid or gaseous wastes, or toxic waste produc ...
included a higher percentage of food waste in their diet, birds nesting near roads consumed more road-killed vertebrates, and those nesting far from these sources of food ate more
arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arth ...
s and plant material. Fledging success was higher for those using human garbage as a food source. In contrast, a 1984–1986 study of common raven diet in an agricultural region of southwestern Idaho found that cereal grains were the principal constituent of pellets, though small mammals, grasshoppers, cattle carrion and birds were also eaten. One behaviour is recruitment, where juvenile ravens call other ravens to a food bonanza, usually a carcass, with a series of loud yells. In ''
Ravens in Winter ''Ravens in Winter'' is a 1989 book by Bernd Heinrich. It is a study of the behaviour of ravens in the forests of Maine. Reception A review of ''Ravens in Winter'' by ''Publishers Weekly'' wrote "The story related here, which is constructed from h ...
'', Bernd Heinrich posited that this behaviour evolved to allow the juveniles to outnumber the resident adults, thus allowing them to feed on the carcass without being chased away. A more mundane explanation is that individuals co-operate in sharing information about carcasses of large mammals because they are too big for just a few birds to exploit.Heinrich, B. (1999). ''Mind of the Raven: Investigations and Adventures with Wolf-Birds'' pp. 119–120. New York: Cliff Street Books. Experiments with baits however show that such recruitment behaviour is independent of the size of the bait. Furthermore, there has been research suggesting that the common raven is involved in seed dispersal. In the wild, the common raven chooses the best habitat and disperses seeds in locations best suited for its survival.


Intelligence

The brain of the common raven is among the largest of any bird species. Specifically, their
hyperpallium The hyperpallium (formerly called the hyperstriatum or the wulst) is the destination for lemnothalamic projections in birds. The projections as well as the granular cells at the destination of the lemnothalamic projections to the hyperpallium are ...
is large for a bird. They display ability in problem-solving, as well as other
cognitive Cognition refers to "the mental action or process of acquiring knowledge and understanding through thought, experience, and the senses". It encompasses all aspects of intellectual functions and processes such as: perception, attention, thought, ...
processes such as imitation and insight. Linguist Derek Bickerton, building on the work of biologist Bernd Heinrich, has argued that ravens are one of only four known animals (the others being
bee Bees are winged insects closely related to wasps and ants, known for their roles in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyly, monophyletic lineage within the ...
s, ants, and humans) who have demonstrated displacement, the capacity to communicate about objects or events that are distant in space or time. Subadult ravens roost together at night, but usually forage alone during the day. However, when one discovers a large carcass guarded by a pair of adult ravens, the unmated raven will return to the roost and communicate the find. The following day, a flock of unmated ravens will fly to the carcass and chase off the adults. Bickerton argues that the advent of linguistic displacement was perhaps the most important event in the evolution of human language, and that ravens are the only other vertebrate to share this with humans. One experiment designed to evaluate insight and problem-solving ability involved a piece of meat attached to a string hanging from a perch. To reach the food, the bird needed to stand on the perch, pull the string up a little at a time, and step on the loops to gradually shorten the string. Four of five common ravens eventually succeeded, and "the transition from no success (ignoring the food or merely yanking at the string) to constant reliable access (pulling up the meat) occurred with no demonstrable trial-and-error learning." This supports the hypothesis that common ravens are 'inventors', implying that they can solve problems. Many of the feats of common ravens were formerly argued to be stereotyped innate behaviour, but it now has been established that their aptitudes for solving problems individually and learning from each other reflect a flexible capacity for intelligent insight unusual among non-human animals. Another experiment showed that some common ravens could intentionally deceive their conspecifics. A study published in 2011 found that ravens can recognise when they are given an unfair trade during reciprocal interactions with conspecifics or humans, retaining memory of the interaction for a prolonged period of time. Birds that were given a fair trade by experimenters were found to prefer interacting with these experimenters compared to those that did not. Furthermore, ravens in the wild have also been observed to stop cooperating with other ravens if they observe them cheating during group tasks. Common ravens have been observed calling wolves to the site of dead animals. The wolves open the carcass, leaving the scraps more accessible to the birds. They watch where other common ravens bury their food and remember the locations of each other's food caches, so they can steal from them. This type of theft occurs so regularly that common ravens will fly extra distances from a food source to find better hiding places for food. They have also been observed pretending to make a cache without actually depositing the food, presumably to confuse onlookers. Common ravens are known to steal and cache shiny objects such as pebbles, pieces of metal, and golf balls. One theory is that they hoard shiny objects to impress other ravens. Other research indicates that juveniles are deeply curious about all new things, and that common ravens retain an attraction to bright, round objects based on their similarity to bird eggs. Mature birds lose their intense interest in the unusual, and become highly
neophobic Neophobia is the fear of anything new, especially a persistent and abnormal fear. In its milder form, it can manifest as the unwillingness to try new things or break from routine. In the context of children the term is generally used to indicate ...
. The first large-scale assessment of ravens' cognitive abilities suggests that, by four months of age, ravens do about as well as adult
chimps The chimpanzee (''Pan troglodytes''), also known as simply the chimp, is a species of great ape native to the forest and savannah of tropical Africa. It has four confirmed subspecies and a fifth proposed subspecies. When its close relative th ...
and orangutans on tests of causal reasoning, social learning, theory of mind, etc.


Play

There has been increasing recognition of the extent to which birds engage in play. Juvenile common ravens are among the most playful of bird species. They have been observed to slide down snowbanks, apparently purely for fun. They even engage in games with other species, such as playing catch-me-if-you-can with wolves, otters and dogs. Common ravens are known for spectacular aerobatic displays, such as flying in loops or interlocking talons with each other in flight. They are also one of only a few wild animals who make their own toys. They have been observed breaking off twigs to play with socially.


Relationship with humans


Conservation and management

Compared to many smaller '' Corvus'' species (such as American crow), ravens prefer undisturbed mountain or forest habitat or rural areas over urban areas. In other areas, their numbers have increased dramatically and they have become agricultural
pests PESTS was an anonymous American activist group formed in 1986 to critique racism, tokenism, and exclusion in the art world. PESTS produced newsletters, posters, and other print material highlighting examples of discrimination in gallery represent ...
. Common ravens can cause damage to crops, such as nuts and grain, or can harm livestock, particularly by killing young goat kids, lambs and calves. Ravens generally attack the faces of young livestock, but the more common raven behaviour of scavenging may be misidentified as predation by ranchers. In the western Mojave Desert, human settlement and land development have led to an estimated 16-fold increase in the common raven population over 25 years. Towns, landfills, sewage treatment plants and artificial ponds create sources of food and water for scavenging birds. Ravens also find nesting sites in utility poles and ornamental trees, and are attracted to roadkill on highways. The explosion in the common raven population in the Mojave has raised concerns for the desert tortoise, a threatened species. Common ravens prey upon juvenile tortoises, which have soft shells and move slowly. Plans to control the population have included shooting and trapping birds, as well as contacting landfill operators to ask that they reduce the amount of exposed garbage. A hunting bounty as a method of control was historically used in Finland from the mid-18th century until 1923. Culling has taken place to a limited extent in
Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S ...
, where the population increase in common ravens is threatening the vulnerable Steller's eider (''Polysticta stelleri''). Ravens, like other corvids, are definitive hosts of West Nile Virus (WNV). The transmission can be from infected birds to humans, and ravens are susceptible to WNV. However, in a 2010 study, it was shown that the California Common Ravens did not have a high positivity rate of WNV.


Cultural depictions

Across its range in the Northern Hemisphere, and throughout human history, the common raven has been a powerful symbol and a popular subject of mythology and folklore. In some
Western tradition Eugen Joseph Weber (April 24, 1925 – May 17, 2007) was a Romanian-born American historian with a special focus on Western civilization. Weber became a historian because of his interest in politics, an interest dating back to at least the ag ...
s, ravens have long been considered to be birds of ill omen, death and evil in general, in part because of the negative symbolism of their all-
black Black is a color which results from the absence or complete absorption of visible light. It is an achromatic color, without hue, like white and grey. It is often used symbolically or figuratively to represent darkness. Black and white ha ...
plumage and the eating of
carrion Carrion () is the decaying flesh of dead animals, including human flesh. Overview Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters (or scavengers) include crows, vultures, c ...
. In Sweden, ravens are known as the ghosts of murdered people, and in Germany as the souls of the damned. In Danish folklore, valravne that ate a king's heart gained human knowledge, could perform great malicious acts, could lead people astray, had superhuman powers, and were "terrible animals".Kristensen, Evald Tang. (1980) ''Danske Sagn: Som De Har Lyd I Folkemunde'', Nyt Nordisk Forlag Arnold Busck, Copenhagen. . p. 132. As in traditional mythology and folklore, the common raven features frequently in more modern writings such as the works of William Shakespeare, and, perhaps most famously, in the poem " The Raven" by
Edgar Allan Poe Edgar Allan Poe (; Edgar Poe; January 19, 1809 – October 7, 1849) was an American writer, poet, editor, and literary critic. Poe is best known for his poetry and short stories, particularly his tales of mystery and the macabre. He is wide ...
. Ravens have appeared in the works of Charles Dickens, J. R. R. Tolkien,
Stephen King Stephen Edwin King (born September 21, 1947) is an American author of horror, supernatural fiction, suspense, crime, science-fiction, and fantasy novels. Described as the "King of Horror", a play on his surname and a reference to his high s ...
, George R. R. Martin and Joan Aiken among others. It continues to be used as a symbol in areas where it once had mythological status: as the national bird of
Bhutan Bhutan (; dz, འབྲུག་ཡུལ་, Druk Yul ), officially the Kingdom of Bhutan,), is a landlocked country in South Asia. It is situated in the Eastern Himalayas, between China in the north and India in the south. A mountai ...
(
Kings of Bhutan Bhutan was founded and unified as a country by Ngawang Namgyal, 1st Zhabdrung Rinpoche in the mid–17th century. After his death in 1651, Bhutan nominally followed his recommended "dual system of government". Under the dual system, government ...
wear the Raven Crown), official bird of the Yukon territory, and on the coat of arms of the Isle of Man (once a Viking colony). In Persia and Arabia the raven was held as a bird of bad omen but a 14th-century Arabic work reports use of the raven in falconry. The modern
unisex given name A unisex name (also known as an epicene name, a gender-neutral name or an androgynous name) is a given name that is not gender-specific. Unisex names are common in the English-speaking world, especially in the United States. By contrast, some c ...
''
Raven A raven is any of several larger-bodied bird species of the genus ''Corvus''. These species do not form a single taxonomic group within the genus. There is no consistent distinction between "crows" and "ravens", common names which are assigned t ...
'' is derived from the English word "raven". As a masculine name, ''Raven'' parallels the Old Norse '' Hrafn'', and Old English ''*Hræfn'', which were both bynames and
personal name A personal name, or full name, in onomastic terminology also known as prosoponym (from Ancient Greek πρόσωπον / ''prósōpon'' - person, and ὄνομα / ''onoma'' - name), is the set of names by which an individual person is known ...
s.


Mythology

In Tlingit and Haida cultures, Raven was both a trickster and
creator god A creator deity or creator god (often called the Creator) is a deity responsible for the creation of the Earth, world, and universe in human religion and mythology. In monotheism, the single God is often also the creator. A number of monolatris ...
. Related beliefs are widespread among the peoples of Siberia and northeastern Asia. The Kamchatka Peninsula, for example, was supposed to have been created by the raven god Kutkh. There are several references to common ravens in the
Old Testament The Old Testament (often abbreviated OT) is the first division of the Christian biblical canon, which is based primarily upon the 24 books of the Hebrew Bible or Tanakh, a collection of ancient religious Hebrew writings by the Israelites. The ...
of the
Bible The Bible (from Koine Greek , , 'the books') is a collection of religious texts or scriptures that are held to be sacred in Christianity, Judaism, Samaritanism, and many other religions. The Bible is an anthologya compilation of texts o ...
and it is an aspect of Mahakala in
Bhutan Bhutan (; dz, འབྲུག་ཡུལ་, Druk Yul ), officially the Kingdom of Bhutan,), is a landlocked country in South Asia. It is situated in the Eastern Himalayas, between China in the north and India in the south. A mountai ...
ese mythology. In
Norse mythology Norse, Nordic, or Scandinavian mythology is the body of myths belonging to the North Germanic peoples, stemming from Old Norse religion and continuing after the Christianization of Scandinavia, and into the Nordic folklore of the modern period ...
,
Huginn In Norse mythology, Huginn (Old Norse: "thought"Orchard (1997:92).) and Muninn (Old Norse "memory"Orchard (1997:115). or "mind"Lindow (2001:186).) are a pair of ravens that fly all over the world, Midgard, and bring information to the god Odin. H ...
(from the Old Norse for "thought") and Muninn (from the Old Norse for "memory" or "mind") are a pair of ravens that fly all over the world of humans, Midgard, and bring the god
Odin Odin (; from non, Óðinn, ) is a widely revered Æsir, god in Germanic paganism. Norse mythology, the source of most surviving information about him, associates him with wisdom, healing, death, royalty, the gallows, knowledge, war, battle, v ...
information. Additionally among the Norse, raven banner standards were carried by such figures as the
Jarls of Orkney Earl of Orkney, historically Jarl of Orkney, is a title of nobility encompassing the archipelagoes of Orkney and Shetland, which comprise the Northern Isles of Scotland. Originally Scandinavian Scotland, founded by Norse invaders, the status of ...
, King Cnut the Great of England, Norway and Denmark, and
Harald Hardrada Harald Sigurdsson (; – 25 September 1066), also known as Harald III of Norway and given the epithet ''Hardrada'' (; modern no, Hardråde, roughly translated as "stern counsel" or "hard ruler") in the sagas, was King of Norway from 1046 t ...
. In the British Isles, ravens also were symbolic to the
Celts The Celts (, see pronunciation for different usages) or Celtic peoples () are. "CELTS location: Greater Europe time period: Second millennium B.C.E. to present ancestry: Celtic a collection of Indo-European peoples. "The Celts, an ancien ...
. In Irish mythology, the goddess Morrígan alighted on the hero Cú Chulainn's shoulder in the form of a raven after his death. In Welsh mythology they were associated with the Welsh god Bran the Blessed, whose name translates to "raven." According to the ''
Mabinogion The ''Mabinogion'' () are the earliest Welsh prose stories, and belong to the Matter of Britain. The stories were compiled in Middle Welsh in the 12th–13th centuries from earlier oral traditions. There are two main source manuscripts, create ...
'', Bran's head was buried in the White Hill of London as a talisman against invasion. A legend developed that England would not fall to a foreign invader as long as there were ravens at the Tower of London; although this is often thought to be an ancient belief, the official Tower of London historian, Geoff Parnell, believes that this is actually a romantic Victorian invention. In the Jewish,
Christian Christians () are people who follow or adhere to Christianity, a monotheistic Abrahamic religion based on the life and teachings of Jesus Christ. The words ''Christ'' and ''Christian'' derive from the Koine Greek title ''Christós'' (Χρι ...
and
Islamic Islam (; ar, ۘالِإسلَام, , ) is an Abrahamic monotheistic religion centred primarily around the Quran, a religious text considered by Muslims to be the direct word of God (or '' Allah'') as it was revealed to Muhammad, the mai ...
traditions, the raven was the first animal to be released from Noah's Ark. "So it came to pass, at the end of forty days, that Noah opened the window of the ark which he had made. Then he sent out a raven, which kept going to and fro until the waters had dried up from the earth. He also sent out from himself a dove, to see if the waters had receded from the face of the ground." The raven is mentioned 12 times in the Bible. In the New Testament Jesus tells a parable using the raven to show how people should rely on God for their needs and not riches ( Luke 12:24).Luke 12:24 (New Living Translation)
Biblegateway.com. Retrieved on 2012-12-19.
The raven is also mentioned in the Quran at the story of
Cain and Abel In the biblical Book of Genesis, Cain ''Qayīn'', in pausa ''Qāyīn''; gr, Κάϊν ''Káïn''; ar, قابيل/قايين, Qābīl / Qāyīn and Abel ''Heḇel'', in pausa ''Hāḇel''; gr, Ἅβελ ''Hábel''; ar, هابيل, Hāb� ...
.
Adam Adam; el, Ἀδάμ, Adám; la, Adam is the name given in Genesis 1-5 to the first human. Beyond its use as the name of the first man, ''adam'' is also used in the Bible as a pronoun, individually as "a human" and in a collective sense as " ...
's firstborn son Cain kills his brother Abel, but he does not know what to do with the corpse: "Then Allah sent a raven scratching up the ground, to show him how to hide his brother's naked corpse. He said: Woe unto me! Am I not able to be as this raven and so hide my brother's naked corpse? And he became repentant."(بَعَثَ اللّهُ غُرَابًا يَبْحَثُ فِي الأَرْضِ لِيُرِيَهُ كَيْفَ يُوَارِي سَوْءةَ أَخِيهِ قَالَ يَا وَيْلَتَا أَعَجَزْتُ أَنْ أَكُونَ مِثْلَ هَذَا الْغُرَابِ فَأُوَارِيَ سَوْءةَ أَخِي فَأَصْبَحَ مِنَ النَّادِمِينَ) Qur'an 5:31, translation: Pickthall, Marmaduke ''The Meaning of the Glorious Koran: An Explanatory Translation'', Amana Publications, 1st edition (1996)


References


Cited texts

* * *


Further reading

* Heinrich, B. (1999). ''Mind of the Raven: Investigations and Adventures with Wolf-Birds.'' New York: Cliff Street Books.


External links


RSPB: Raven
– Cornell Lab of Ornithology *
Ageing and sexing (PDF; 3.1 MB) by Javier Blasco-Zumeta & Gerd-Michael HeinzeCommon raven images at ARKive''Corvus corax''
at Encyclopedia of Life

– USGS Patuxent Bird Identification InfoCenter (includes CBC/BBS range maps) *

at naturesongs.com {{Featured article Corvus Holarctic birds Ravens Talking birds Territorial symbols of Yukon Birds described in 1758 Articles containing video clips Fauna of the San Francisco Bay Area Taxa named by Carl Linnaeus