Carrion crow

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Carrion crow
Carrion crow (Corvus corone), Hooded crow morph

Carrion crow ( Corvus corone ), Hooded crow morph

Systematics
Order : Passerines (Passeriformes)
Subordination : Songbirds (passeri)
Family : Corvids (Corvidae)
Genre : Ravens and Crows ( Corvus )
Type : Carrion crow
Scientific name
Corvus corone
Linnaeus , 1758

The carrion crow ( Corvus corone ) is a bird art from the family of corvids (Corvidae). It occurs in a gray-black ("hooded crow") and a completely black morph ("carrion crow") and, with a body length of 45 to 47 cm, is one of the larger representatives of the ravens and crows ( Corvus ).

Occurrence

It lives in warm to cold temperate Eurasia from the northern edge of the Mediterranean to the Pacific and occurs in all open to semi-open habitats with trees. The northern populations migrate south in winter. Carrion crows are omnivores and feed on seeds, insects , eggs, meat, and human waste. While carrion crows, as young and unmated animals, live mainly in swarms ("bachelorette swarms"), breeding pairs establish territories that they actively defend against conspecifics. The species usually builds their nests in the crown of tall trees. The breeding season begins in the south of the range in February, in the north often not until April, the young birds fly out around 50 days after they have laid their eggs.

The carrion crow was set up as a species by Carl von Linné in 1758 . It is traditionally divided into two large subspecies complexes, which are based on the color of the plumage. While a separate species status for the hooded crow morph has been discussed for a long time, more recent DNA analyzes have not been able to determine a genetic separation between carrion and hooded crows. Instead, the population is divided into a western and an eastern Palearctic clade , which also includes the Chinese collar-necked crow ( Corvus pectoralis ). The taxonomic consequences of this are so far unclear. The closest relatives of the carrion crow are the American crow ( Corvus brachyrhynchos ) and the common crow ( Corvus caurinus ) from North America, which are ecologically and morphologically very similar and probably separated from it in the Pliocene . The total population is estimated to be an eight-digit number of individuals. Because of this large population and because the species is considered a successful cultivator , BirdLife International classifies it as not endangered.

features

Physique and plumage

Photo of a black carrion crow on the beach
Carrion crow morph of the carrion crow. The birds appear strong and compact, the plumage is weaker than that of most other species of crows.
Carrion crows caring for each other's plumage

When fully grown, carrion crows reach a body length of 45 to 47 cm and a wingspan of 93 to 104 cm. Their high, slightly curved and powerful beak, their short, close-fitting leg feathers and their voluminous body plumage give them a compact, stocky appearance. Their wings are relatively long and moderately fingered, their tail broad and slightly rounded. When put on, the wing tips protrude just above the tip of the tail. Statistically, there is a sexual dimorphism between males and females : female carrion crows remain slightly smaller on average and are somewhat slimmer. The body weight of adult males is 418–740 g, that of females 370–670 g. The male wing measures between 292 and 387 mm, female animals reach wing lengths of 283 to 370 mm. The tail of the males is 173–202 mm long, that of the females 170–191 mm. The barrel measures 57–68 mm in male, 53–62 mm in female carrion crows. The bird's beak reaches lengths of 52–65 mm (males) and 50–57 mm (females). Due to its size, the carrion crow has only a few predators, only specialized bird hunters such as goshawk ( Accipiter gentilis ), peregrine falcon ( Falco peregrinus ) or eagle owl ( Bubo bubo ) are able to beat adult animals.

Head study of a carrion crow
CrowHeadClosed1.jpg
Hooded crow morph. Its curved, strong beak is characteristic of the species; the nasal bristles only cover about half of it.
Cranium Corvus corone corone.jpg
Bone preparation (here: skull) of a carrion crow (Corvus corone corone) after enzymatic maceration, chemically defatted and chemically bleached.

The species occurs in a completely black and a black-gray plumage morph . This can also lead to mixed forms of different characteristics: "doctor crows". Called the black morph Rabenkrähe, characterized in fresh plumage by a matte, metallic luster of which moves between green and blue and is less pronounced than at about rooks ( C. frugilegus ) or Kolkraben ( C. Corax ). The roots of the breast and belly feathers are light gray. The longer it is worn, the plumage loses its saturation and luster and changes color to a slightly brownish color, especially on the wing feathers . The black-gray morph, the so-called hooded crow, corresponds in the color of the head, the central breast, the tail and the wings of the carrion crow. The neck, back and shoulder coverts, on the other hand, are ash gray to white, as are the small upper tail coverts, the lateral chest, the stomach and the lower tail coverts. The thighs of hooded crows are feathered black, but often covered with a grayish veil. In birds from the Mediterranean area, there are distinct black feather shafts in the white plumage.

The legs and beak of both morphs are slate-colored, the irises of adult birds are dark brown. Juvenile carrion crows are distinguished from adult animals by their less voluminous plumage and their somewhat slimmer silhouette. In addition, the colors of the plumage are tinted brown, and in young hooded crows the black patch on the chest is less pronounced than in adult birds.

Flight image and locomotion

Two hooded crows fly over a blanket of snow
Two carrion crows in flight. The species is mainly characterized by its broad wings with rounded tips. The hand wings are proportionally shorter than those of the rook ( C. frugilegus ).

In the air, carrion crows are characterized by their determined and rather slow flight style, which is carried by powerful, even flaps of their wings. In cross-country flight, the birds usually reach speeds of 35–45 km / h. They show less acrobatic flight maneuvers like those known from other Corvus species such as ravens or rooks, and they also sail less often at high altitudes. In good weather, the flight altitude is usually 20–50 m, in strong winds, on the other hand, the flight is close (0.5–5 m) above the ground. The silhouette of flying carrion crows has broad wings with rounded, moderately fingered tips and relatively short hand wings. The joint is slightly rounded and stands out from the strongly rounded rook and the wedge-shaped joint of the raven.

Carrion crows walk on the ground in a military-style manner. The typical walking gait of the species changes into tripping hopping when in a hurry, in which the wings are sometimes raised slightly until they are flapped simultaneously (simultaneously) without the animals taking off. On clear, level ground, carrion crows often move biped for some distance, for example when people who are familiar to them do not specifically throw chunks of food in front of their beak. In the branches, carrion crows usually jump over distances. The wings are often used here as well. Carrion crows prefer to use high, exposed places and structures such as the edges of houses, tree tops, power lines or antennas as waiting areas . Otherwise, they are often out and about on open lawns, whereby they take relatively little account of the possibilities for cover.

Vocalizations

Subsong of a carrion crow, towards the end of the recording the typical Krah call of the species can be heard.

The calls of carrion crows are very characteristic and can be heard over long distances. The most common call of the birds is a rough, powerful Krah in different variants and different intensities. It is usually used by the birds to feel their voices and is often repeated one to four times. A common modification of this vocal feeling sound is used by male carrion crows in the context of showing off. The krah becomes a creaking , elongated kraar that is repeated rhythmically. The birds assume a typical pose in which the tail is spread, the back is curved and the head is thrown up and down. Hate sounds range from throaty, squawking crow calls for rather harmless birds of prey to a sharp, hasty arr , arr for the goshawk ( Accipiter gentilis ) feared by the carrion crows . The rest of the sound repertoire includes a number of creaking, crowing and rattling calls as well as high, short begging sounds. Young and adult birds can sometimes hear an unmelodious sub- song made up of a number of very different sounds, including calls, ambient noises or the sounds of other animals that have been freed from their usual context. It is usually very quiet and is only sung by young birds in the absence of conspecifics. Adult birds sing alone on high tops or in the nest.

distribution

The carrion crow lives in a Palearctic area that stretches from the Pacific and temperate Eurasia to the Atlantic coast and the Mediterranean Sea . The species is absent in the warm temperate East Asia , largely spares the Central Asian steppe belt and does not reach the polar sea except in Fennoscandinavia . The easternmost deposits are in the Russian Far East and extend from Kamchatka southwest over the Kuril Islands , Sakhalin and Japan . The southern limit of the range of the carrion crow runs through northern China, turns shortly to the south in the center of the country and to the west coincides roughly with the edge of the Tibetan plateau . In Yunnan there is a small breeding enclave, the east coast region of China up to the level of Hainan serves as winter quarters for the species. Westward the breeding population rich along the Tibetan plateau up to the Amurdarja and the Aral region . The species is missing as a breeding bird between the Aral Sea and the Caspian Sea . South of the region, the Elburs and the Zagros belong to the breeding area, the lowlands between the two mountains are among the winter quarters. To the west of the Zagros, the lower reaches of the Euphrates forms the area boundary. In the upper reaches of the Euphrates and Tigris , the carrion crow occurs only as a winter guest, in Anatolia and the Caucasus region, on the other hand, occurs across the board as a breeding bird. The Artareal stretches from Asia Minor southwards along the western Mediterranean coast to the Nile delta and lower reaches to Aswan . On the northern edge of the Mediterranean Sea, the distribution area runs over the Greek islands and the mainland and follows the north coast to Spain . The large Mediterranean islands also belong to the breeding area. The carrion crow is absent in southern Andalusia , but is otherwise found on the entire European mainland and from the British Isles to Karelia . The northern distribution limit reaches approximately up to the edge of the boreal forest and fluctuates by about 70 ° N .

Distribution of the carrion crow ( Corvus c. Corone ) and the hooded crow ( C. c. Cornix ) in Europe. The yellow line is the contact zone of both subspecies.

The geographical distribution of carrion and hooded crow morphs is very homogeneous and stable. Black animals come from the Iberian Peninsula to England and in Germany to around the Elbe . In Ireland, Scotland, Scandinavia, Denmark, Eastern Europe, on the Balkan and Apennine Peninsula , in the Eastern Mediterranean, the Mesopotamia and Russia to the Yenisei , the birds are gray-black throughout. To the east of this, there is a black population. Between the three areas there are transition zones that are between 70 and 130 km wide and have hardly shifted in the past decades. In temperate climates, the carrion crow is a predominant resident bird and only occasionally wanders into warmer regions in winter. During this time of year, the Siberian breeding population migrates to eastern and southeastern China, northern Pakistan and northeastern Iran.

habitat

Hooded crow with dead gable in Lake Malchin

Open and semi-open landscapes mark the preferred habitats of carrion crows. The birds are dependent on trees, tall bushes or comparable anthropogenic structures as sleeping and nesting places as well as waiting areas . Regionally, rock cliffs can also take on this function. For foraging they use extensive, short-grassed areas that are easily manageable, so both elements must be in a certain proximity to each other. In forest areas, the species is therefore restricted to bank areas, moors and clearings; the deforestation of large parts of Eurasia in the Holocene , however, opened up new habitats such as arable land and pasture land, villages and cities. The greening of major European cities through parks and avenues allowed them to penetrate their centers from the 19th century onwards. Modern urbanization began with the carrion crow in Europe only hesitantly. Only with increasing prosperity and widespread availability of human waste in the second half of the 20th century were animals able to establish themselves in large numbers in cities. In the meantime, because of a better food supply and less pressure from hunting and predators, it usually occurs in higher population densities than in rural areas. The carrion crow lives in a large number of very different habitats, but is generally absent in dense forests and on steep slopes. An important location factor are goshawk territories , in which carrion crows usually cannot breed successfully. The species occurs from sea level up to about 750 m, in some high mountains such as the Alps it can also be found in locations above 1000 m, sometimes even up to 2000 m.

Way of life

nutrition

Two black carrion crows sit on a garbage can
Two carrion crows at a wintry garbage can in Annecy . In the fall and winter, human waste becomes the main source of food for urban crows.
Video: A hooded crow is looking for food (possibly previously hidden) in a rain gutter in Berlin.

Carrion crows are omnivores and have a very varied diet. The main food sources of the species are grain seeds and invertebrates, in addition to small vertebrates , bird eggs, carrion and waste. The composition of the food spectrum varies greatly depending on the availability, habitat and season. Grain is important in Oxfordshire, UK all year round, but especially in autumn and winter. Small fruits and fruit become important towards autumn, but usually play a subordinate role in the rest of the year. On the tops of berry-bearing female sea buckthorn trees on the Baltic Sea coast, hooded crows can be seen in groups pecking at the ripe fruit. In spring, the number of eaten earthworms and beetles increases sharply, followed by an increase in other insects that have been eaten . Bird eggs are eaten by carrion crows in spring and early summer when they are sufficiently available. Small mammals move into the center of attention a little later, towards summer. Elsewhere, there can be significantly different accents in the food spectrum: In pasture regions carrion is an important source of food in winter. In coastal areas, depending on the season, crustaceans and seabird eggs can be eaten almost exclusively ; On the shallow stretches of beach on the Baltic Sea coast, hooded crows can be seen unafraid to follow the running waves into the water and peck for small prey. Waste often dominates cities; in parks and cemeteries they like to have people they trust provide them with food (such as peanuts in shell). Nestlings are fed with animal food, mainly earthworms, insect larvae and bird eggs.

When foraging for food, carrion crows usually go in the fields , pecking insects and other food objects from the sward . The animals drop hard-shelled nuts from flight onto hard surfaces until they break open. Carrion crows are skilled at reaching hard-to-reach pieces of food or sometimes grabbing live vertebrates from flight or on the ground. Animals from some Scandinavian populations pull unsupervised fishing lines in order to get hold of the fish hanging on them. Fish are often caught flying out of the water. Like most corvids, the carrion hides excess food under leaves, bark or in specially dug holes in the ground in order to later retrieve and eat it.

Social behavior

Carrion crows in Mecklenburg

Outside the breeding season, carrion crows live together in smaller flocks, which in turn combine to form larger flocks, especially at dusk, provided they fly to their common sleeping trees. During the breeding season, adult crows form breeding pairs that distance themselves from the swarms and limit themselves to their breeding territory. Non-breeders, especially young animals, stay behind in the swarms and stay away from the breeding grounds. If a brood partner fails, it is usually quickly replaced by an animal from a neighboring swarm. Territories are predominantly held by the male, while single female carrion crows give them up. If there is a good food supply, especially in urban green spaces, it can also lead to a colony-like accumulation of breeding grounds, which are then defended less aggressively. Solid individual relationships exist within the swarms, which can be seen in the flock's restlessness when individual animals are suddenly absent.

Reproduction

Crows clutch

The breeding season of the species begins between the end of February and the end of May, depending on the regional climate, food availability and experience of the breeding partners. The nest is usually built high in trees, but also high on masts or in building and rock niches. The most important factors are cover and, in settlements, proximity to houses. It consists of a massive, four-layer construction, the outermost layer of which consists of thick twigs and is lined on the inside with increasingly fine materials such as wool, feathers, plant fibers or fabric. It usually measures 23–47 cm in diameter and is usually not reused in subsequent years. The female lays two to six eggs, bluish-green in color, in the nest. The young hatch from them after around 20 days and fledge after a further 28-38 days. During breeding, clutches and nestlings are threatened primarily by conspecifics and real martens ( Martes spp.). The nest losses are between 40 and 93% depending on the year and region, with forest breeders usually being the most affected. The maximum age that can be reached in the wild is over 19 years.

intelligence

Carrion crows are known for their intelligent behavior. Their clever behavior is made possible by a disproportionate encephalization of the brain. Among other things, this enables crows to distinguish numbers of up to 30, whereby their discriminatory power decreases with increasing numbers. Furthermore, carrion crows can follow abstract rules and distinguish between human and crow faces. The working memory of carrion crows has a capacity of 4 and is thus comparable to that of rhesus monkeys .

Carrion crows reach the highest level of object permanence , with the various levels only being reached in the course of development. Like ravens , carrion crows show the “ A-not-B search error ”.

Systematics and taxonomy

Color lithograph of a hooded and carrion crow
Carrion and hooded crow, color print from Johann Friedrich Naumann's Natural History of the Birds of Central Europe . Whether both forms should be considered as separate species or as separate taxa at all has been a matter of dispute since the 19th century.

The color distinctly different Raven and crows were 1758 by Carolus Linnaeus in the tenth edition of his Systema Naturae as independent species firstdescribed : The Rabenkrähe as Corvus corone that Nebelkrähe as Corvus cornix . It has been known since the early 19th century that both are mutually reproductive and produce hybrid forms as offspring. The authoritative natural histories of Johann Friedrich Naumann and Constantin Wilhelm Lambert Gloger as well as Paul Matschie 's geographic study of the distribution of both forms in 1887 explicitly pointed to the border zones in which both forms mixed and which ran through all of Europe. The importance of these hybrid zones was controversial. While some of the taxonomists and ornithologists - starting with Naumann - saw them as evidence that hooded crows and carrion crows should only be treated as subspecies of a single species, others pointed to the narrow width and the stability of the hybrid zones: that they can not go further spread, is a sign of insufficient fertility of the mixed race produced there, the parents must therefore be genetically far apart. Investigations of the morphology , the utterances and the behavior could not help to clarify the question, because although they were able to determine differences in places, these were not consistent and often even contradicting across different regions. With the emergence of genetics in the middle of the 20th century, doubts about the expressiveness of the hybrid zones also arose. They argued that outside of these zones there could be hybrids that looked like purebred crows or hooded crows on the outside, but still had mixed pairs of parents. Accordingly, the taxonomic treatment of both forms has fluctuated over the decades and over the years: in part, they were classified as C. corone corone and C. corone cornix as subspecies of the species C. corone , in part the hooded crow was separated from the carrion crow as Corvus cornix .

Regardless of whether Raven and Hooded Crow to the same species include subspecies were also set up within the two Morphenpopulationen: The separated by the range of the hooded crow from the western crows East Asian black birds were in 1849 by Eduard Friedrich Eversmann as a subspecies C. corone orientalis delimited. The hooded crow populations were also recorded in C. cornix capellanus Sclater , 1876 ( Iraq and western Iran), C. c. sharpii Oates , 1889 (southern Central Asia and Eastern Europe) and C. c. pallescens Madarász , 1904 (western Mediterranean coast) divided. The status and the delimitation of these subspecies of the hooded crow morph were always controversial.

 Corvus  

 American Crow  ( C. brachyrhynchos ) +  Sundkrähe  ( C. caurinus )


   

 Hooded crows + Western carrion crows


   

 Ostasiatische crows +  collar Crow  ( C. pectoralis )




Template: Klade / Maintenance / Style
Systematics of the carrion crow according to Haring et al. (2012). The species also includes the collar crow ( C. pectoralis ) from a genetic point of view and, apart from a west-east one, shows no genetic differentiation that would support a separation into subspecies.

The first DNA analyzes on the subject were carried out from 2000. None of them could establish a genetic separation between hooded and carrion crow morphs. Instead, they traced a clear separation between birds from the western and eastern Palearctic. According to these studies, the western clade extends from Europe to western China and northern Kamchatka . The eastern clade mainly comprised southeastern Siberia, the southern tip of Kamchatka and east Asia around the Sea of ​​Japan . In addition, gene samples from collar crows ( C. pectoralis ) from the east coast of China were assigned to her, which would be genetically in the middle of the Corvus corone species . The subspecies boundaries postulated in the 20th century were not reflected in the distribution of the haplogroups . The studies identified the American crow ( C. brachyrhynchos ) and the carrion crow ( C. caurinus ) as sister clades of the carrion crow group , which are very similar to the black morph of the carrion crow and occupy their ecological niche in North America . The two clades probably separated about four million years ago in the Pliocene when the land connection between Eurasia and North America broke off. How the stable mixing zones between the two morphs come about or are maintained has not been fully clarified. The different coloration of Raven and crows caused few genes by different degrees of expression, in the genome of the production of melanin control. Although there are no other known significant genetic differences between the two morphs, there is a noticeable difference in color. According to the authors of the corresponding studies, genetic exchange continues to take place via the hybrid zones. All genes except those involved in melanin production are passed on. Assortative pairing , in which the morph of the parents is preferred , is likely to ensure the stability of the hybrid zones .

status

The carrion crow has been heavily persecuted by humans as an agricultural pest and nest robber in Europe since the 19th century. Birds were shot down, poisoned with bait and their eggs destroyed. Regionally, this sometimes led to a sharp decline in the number of the species, but this never resulted in extinction. Hunting by humans is still one of the main causes of mortality and population-weakening causes. The losses were mostly compensated by migrating birds or after the pursuit measures were stopped. In the 20th century, land consolidation in particular led to habitat losses in some European areas, and exposure to pesticides and heavy metals made the carrion crows a problem. At the end of the 20th century, hunting pressure eased, which led to a regional recovery. At the same time, the carrion crow gained a foothold in many cities as a cultural follower and was able to spread successfully there. In contrast, the population in the Nile Delta is declining, which is probably due to the increased use of pesticides. Otherwise, the species is considered to be harmless due to its large distribution area and large population. BirdLife International estimates the European population at 21–51 million animals or 7–17 million breeding pairs. Based on the assumption that Europe is home to a quarter to half of the world's population of the species, the institution estimates the global population at 43–204 million birds; However, more precise counts, estimates and projections have so far been pending, especially for Asia.

literature

  • Hans-Günther Bauer, Einhard Bezzel , Wolfgang Fiedler : The compendium of birds in Central Europe. Volume 2. Passeriformes. Aula-Verlag, Wiebelsheim 2005, ISBN 3-89104-648-0 .
  • Stanley Cramp , Christopher M. Perrins : Handbook of the Birds of Europe, the Middle East and North Africa: The Birds of the Western Palearctic . 8: Crows to Finches. Oxford University Press, Oxford 1994, ISBN 0-19-854679-3 .
  • Urs N. Glutz von Blotzheim , Kurt M. Bauer (ed.): Handbook of the birds of Central Europe . 2nd Edition. tape 13 / III . Aula, Wiesbaden 1993, ISBN 3-89104-542-5 .
  • Jonathan Ekstrom, Stuart Butchart: Carrion Crow (Corvus corone) . BirdLife International, birdlife.org, 2012 ( full text ).
  • Elisabeth Haring, Barbara Däubl, Wilhelm Pinsker , Alexey Kryukov, Anita Gamauf: Genetic divergences and intraspecific variation in corvids of the genus Corvus (Aves: Passeriformes: Corvidae) - a first survey based on museum specimens . In: Journal of Zoological Systematics and Evolutionary Research . tape 50 , no. 3 , 2012, p. 230-246 , doi : 10.1111 / j.1439-0469.2012.00664.x .
  • Knud A. Jønsson, Pierre-Henri Fabre, Martin Irestedt: Brains, tools, innovation and biogeography in crows and ravens . In: BMC Evolutionary Biology . tape 12 , no. 72 , 2012, p. 1-12 , doi : 10.1186 / 1471-2148-12-72 .
  • Alexey Kryukov, Hitoshi Suzuki: Phylogeography of Carrion, Hooded, and Jungle Crows (Aves, Corvidae) Inferred from Partial Sequencing of the Mitochondrial DNA Cytochrome b Gene . In: Russian Journal of Genetics . tape 36 , no. 8 , p. 1111-1118 .
  • Alexey Kryukov, Liudmila Spiridonova, Sumio Nakamura, Elisabeth Haring, Hitoshi Suzuki: Comparative Phylogeography of Two Crow Species: Jungle Crow Corvus macrorhynchos and Carrion Crow Corvus corone . In: Zoological Science . tape 29 , no. 8 , p. 484-492 , doi : 10.2108 / zsj.29.484 .
  • Steve Madge : Carrion Crow (Corvus corone) . Handbook of the Birds of the World Alive, hbw.com, 2009 ( online ).
  • Steve Madge: Hooded Crow (Corvus cornix) . Handbook of the Birds of the World Alive, hbw.com, 2009 ( online ).
  • Paul Matschie: Distribution of the birds in Germany in a cartographic representation . In: Journal of Ornithology . tape 35 , 1887, I. Attempt to illustrate the distribution of Corvus Corone L., Corvus cornix L., and Corvus frugilegus L., p. 617-648 ( PDF ).
  • JW Poelstra, N. Vijay, CM Bossu, H. Lantz, B. Ryll, I. Müller, V. Baglione, P. Unneberg, M. Wikelski, MG Grabherr, JBW Wolf: The genomic landscape underlying phenotypic integrity in the face of gene flow in crows . In: Science . tape 344 , no. 6190 , 2014, p. 1410-1414 , doi : 10.1126 / science.1253226 .
  • Dieter Glandt: Kolkrabe & Co. AULA-Verlag, Wiebelsheim; 2012. ISBN 978-3-89104-760-6

Web links

Commons : Carrion Crow  - Collection of images, videos and audio files
Wiktionary: carrion crow  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ↑ Cramp & Simmons 1994, pp. 193-194.
  2. ↑ Glutz von Blotzheim & Bauer 1993, p. 1900.
  3. ↑ Cramp & Simmons 1994, p. 192.
  4. ↑ a b Glutz von Blotzheim & Bauer 1993, p. 1901.
  5. ↑ Glutz von Blotzheim & Bauer 1993, p. 1867.
  6. ↑ Glutz von Blotzheim & Bauer 1993, pp. 1869-1870.
  7. ↑ Cramp & Simmons 1994, pp. 173-174.
  8. ↑ Glutz von Blotzheim & Bauer 1993, p. 1857.
  9. ↑ Glutz von Blotzheim & Bauer 1993, pp. 1861–1862.
  10. ↑ a b Madge 2013. Retrieved March 2, 2013.
  11. ↑ Glutz von Blotzheim & Bauer 1993, pp. 1886–1889.
  12. ↑ Glutz von Blotzheim & Bauer 1993, pp. 1882–1885.
  13. ↑ Glutz von Blotzheim & Bauer 1993, pp. 1922–1929.
  14. ↑ Glutz von Blotzheim & Bauer 1993, p. 1909.
  15. ↑ Glutz von Blotzheim & Bauer 1993, pp. 1910–1912.
  16. ↑ Cramp & Simmons 1994, pp. 190-191.
  17. ↑ Glutz von Blotzheim & Bauer 1993, p. 1898.
  18. ^ The Animal Aging and Longevity Database. according to: Fransson et al. (2010): EURING list of longevity records for European birds.
  19. ^ Andreas Nieder: Inside the corvid brain — probing the physiology of cognition in crows . In: Current Opinion in Behavioral Sciences (=  Comparative cognition ). tape 16 , August 1, 2017, ISSN  2352-1546 , p. 8-14 , doi : 10.1016 / j.cobeha.2017.02.005 ( sciencedirect.com [accessed February 1, 2019]).
  20. ^ Pavel Němec, Suzana Herculano-Houzel, W. Tecumseh Fitch, Michal Porteš, Radek K. Lučan: Birds have primate-like numbers of neurons in the forebrain . In: Proceedings of the National Academy of Sciences . tape 113 , no. 26 , June 28, 2016, ISSN  0027-8424 , p. 7255-7260 , doi : 10.1073 / pnas.1517131113 , PMID 27298365 , PMC 4932926 (free full text) - ( pnas.org [accessed February 1, 2019]).
  21. ^ Helen M. Ditz, Andreas Nieder: Numerosity representations in crows obey the Weber-Fechner law . In: Proceedings. Biological Sciences . tape 283 , no. 1827 , March 30, 2016, ISSN  1471-2954 , p. 20160083 , doi : 10.1098 / rspb.2016.0083 , PMID 27009227 , PMC 4822466 (free full text) - ( royalsocietypublishing.org [accessed February 1, 2019]).
  22. ↑ Andreas Nieder, Lena Veit: Abstract rule neurons in the endbrain support intelligent behavior in corvid songbirds . In: Nature Communications . tape 4 , November 28, 2013, ISSN  2041-1723 , p. 2878 , doi : 10.1038 / ncomms3878 ( nature.com [accessed February 1, 2019]).
  23. ↑ Katharina F. Brecht, Lysann Wagener, Ljerka Ostojić, Nicola S. Clayton, Andreas Nieder: Comparing the face inversion effect in crows and humans . In: Journal of Comparative Physiology A . tape 203 , no. 12 , December 1, 2017, ISSN  1432-1351 , p. 1017-1027 , doi : 10.1007 / s00359-017-1211-7 , PMID 28905251 , PMC 5696503 (free full text) - (doi.org/10.1007/s00359-017-1211-7 [accessed February 1, 2019]).
  24. ↑ Jonas Rose, Dmitry Balakhonov: Crows Rival Monkeys in Cognitive Capacity . In: Scientific Reports . tape 7 , no. 1 , August 18, 2017, ISSN  2045-2322 , p. 8809 , doi : 10.1038 / s41598-017-09400-0 , PMID 28821812 , PMC 5562807 (free full text) - ( nature.com [accessed February 1, 2019]).
  25. ↑ Almut Hoffmann, Vanessa Rüttler, Andreas Nieder: Ontogeny of object permanence and object tracking in the carrion crow, Corvus corone . In: Animal Behavior . tape 82 , no. 2 , August 1, 2011, ISSN  0003-3472 , p. 359-367 , doi : 10.1016 / j.anbehav.2011.05.012 ( sciencedirect.com [accessed February 1, 2019]).
  26. ^ Matschie 1887.
  27. ↑ Glutz von Blotzheim & Bauer 1993, pp. 1858–1864.
  28. ↑ Cramp & Simmons 1994, p. 172.
  29. ↑ Haring et al. 2012, pp. 5-8.
  30. ^ Kryukov & Suzuki 2000.
  31. ↑ Jønsson et al. 2012.
  32. ↑ Haring et al. 2012.
  33. ↑ Poelstra et al. 2014, pp. 1413-1414
  34. ↑ Bauer et al. 2006, pp. 82-87.
  35. ↑ Madge 2014. Accessed March 2, 2013.
  36. ^ Ekstrom & Butchart 2012. Retrieved March 2, 2014.
This version was added to the list of articles worth reading on September 21, 2015 .