Common raven
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Common raven ( Corvus corax ) |
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| Linnaeus , 1758 |
The Raven ( Corvus corax ) is a bird art from the family of corvids (Corvidae). By human persecution, common ravens were wiped out in large parts of Central Europe by 1940 and then spread again as the persecution eased. The scientific name Corvus corax is made up of the Latin Corvus and the Greek Corax , both of which mean "raven". Kolk , the first syllable of his German name, attested since the 16th century, is probably of onomatopoeic origin, so it imitates the bird's call.
description
With a body length of 54 to 67 cm and a wingspan of 115 to 130 cm, the common raven is larger than a common buzzard and by far the largest European corvid. The difference between male and female animals is small in terms of size, males are on average slightly larger and heavier than females. Adult males from Poland have a wing length of 388–442 mm, mean 423.3 mm and weigh 1080–1370 g, mean 1254 g, females have a wing length of 395–433 mm, mean 413.8 mm and weigh 1070 -1235 g, on average 1147 g. The beak is very large and strong, the ridge of the upper beak is clearly curved downwards.
In adult birds, the plumage is solid black and, depending on the incidence of light, metallic green or blue-violet shiny. The iris is dark brown, legs and beak are black. The feathers on the throat are elongated and lanceolate; especially when the birds call, these feathers stand out clearly. The tail is clearly wedge-shaped at the end. In flight, in addition to the wedge-shaped tail, the long wings, which are clearly narrowed in the hand wing, as well as the strong neck with the large head and the large beak are characteristic.
In young people's plumage, the plumage almost completely lacks the metallic sheen, it is brown-black on the top and brown on the underside. At most the throat shows a faint metallic sheen. The feathers of the throat are not elongated, the tail is less wedge-shaped at the end, but more rounded. The iris is blue-gray. After the first moult, the elongated throat feathers are still missing, at the age of three the birds show the adult plumage.
A variety with white or light gray plumage ( white and white raven ), which occurred in the Faroe Islands , became extinct in 1902 after ruthless pursuit by trophy hunters.
Vocalizations
The most frequently heard call is a loud and sharp "kraa", which is uttered when threatened; if there is a strong threat, “kraa, kraa, kraa, kraa” or “rak, rak, rak, rak” are shouted. When gliding or flapping in pairs over longer distances, as well as in flight maneuvers related to courtship such as air rolls or wave flights, “klong”, “raok” or “oang” are often called individually. In addition, common ravens have a wide variety of vocalizations; their repertoire includes “sounds with several syllables, reminiscent of scouring, grunting, burping, creaking, buzzing and even bright xylophone sounds”; at least 34 different types of calls were found in Central European ravens. After all, ravens like to imitate the sounds and calls of other animal species: calls from crows , the courtship song of the grouse , barking dogs .
Common ravens can change their voices depending on the type of acquaintance with a conspecific: They react to unfamiliar conspecifics with significantly deeper and rougher voices than ravens they are familiar with, and ravens known to them as "friendly" from previous encounters are greeted with a higher voice than they are "Unfriendly" known individuals.
distribution
The huge range of the species covers large parts of the Holarctic . In the Palearctic, it stretches from Ireland , Iceland and Portugal eastwards to Kamchatka on the Pacific coast . In the north-south direction, the common raven occurs in the west from the northern tip of Norway to the Maghreb . In western Siberia , the northern limit of distribution is already reached at the Arctic Circle , further east the species is absent in the northern Siberian lowlands, on the Taimyr peninsula , in the Jana-Indigirka lowlands , in the north in the Kolyma lowlands and in the northern Anjuigebirge .
The southern limit of distribution runs further east in the north of the Arabian Peninsula , in the south from Iraq and Iran via north India and to the north-east turning through central China to Manchuria . In Asia, the species is largely absent in the Central Asian steppe region .
In the Nearctic , the coastal regions of Greenland and North America from Alaska and the northernmost Canada to the south as far as Nicaragua are populated. The species is absent in much of the central and western United States as well as western Mexico and Central America .
The major gaps in distribution in Central and Western Europe and in the eastern United States are caused by human persecution.
Systematics
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The number of subspecies has long been discussed controversially, Glutz von Blotzheim and Bauer recognize eight subspecies, which can only be differentiated by slight differences in color and size:
- C. corax corax : The nominate form populates Europe as well as western and central Siberia as far as Lake Baikal , to the south the distribution extends to the Mediterranean islands, to the north of Iran, the Altai and both Sajan .
- C. c. varius : Iceland and Faroe Islands ; Plumage not so shiny compared to the nominate form, the underside more greenish black.
- C. c. kamtschaticus : Eastern Siberia and Kamchatka , south to the north of Mongolia and northern Japan; Leaf length with 400 to 450 mm, on average 430 mm somewhat larger than with the nominate shape.
- C. c. tibetanus : Tienschan and Pamir to eastern China, south to the Himalayas; Plumage overall and especially on the underside with a strong purple-blue gloss, lanceolate throat-feathers pronounced and long, wing length 470–490 mm, on average 479 mm, even larger than in C. c. kamtschaticus .
- C. c. tingitanus : North Africa to Morocco and Canary Islands ; Plumage more oily iridescent; Wing length on the African mainland with 380-420 mm, on average 401 mm, and on the Canary Islands with 370-405 mm, on average 388 mm significantly less than in the nominate form.
- C. c. laurencei : Arabian Peninsula and Western Asia from Syria and Jordan to the east to northwest India and to the foot of the southern Himalayas; Plumage more steel-blue, worn plumage on the neck, on the upper back and on the throat brownish, wing length 415–474 mm, on average 445 mm somewhat larger than in the nominate form.
- C. c. sinuatus : Western North America.
- C. c. principalis : Northern North America and Greenland , wing length 440–475 mm, on average 455 mm somewhat larger than the nominate form.
According to more recent molecular genetic studies, two distinctly different clades can be distinguished within the species: A Holarctic, whose sister taxon is the tortoise-shell , and another, which only includes the common ravens in the southwest of the USA and whose sister taxon is the white-necked raven ( C. cryptoleucus ). Further studies must show which taxonomic consequences result from this.
habitat
The common raven is very adaptable with regard to the inhabited habitats and inhabits high mountains, forests and open and semi-open landscapes of all kinds from the tundra in the north to the central European cultural steppe to semi-deserts in the south of the distribution area. With decreasing human persecution, areas close to settlements are increasingly being inhabited, for example there were at least 15 breeding pairs in Berlin at the end of the 1990s.
nutrition
Like many corvids, the common raven is omnivorous , with animal parts usually predominating. The food spectrum includes small vertebrates of all kinds and their stages of development (e.g. bird eggs ), larger insects , earthworms and other invertebrates , carrion of all sizes, fruits, agricultural products such as maize and human food waste of all kinds.
Foraging
The strategies for searching for food are enormously variable, due to the very broad food spectrum and the great ability of the species to learn. The birds look for their food mainly in the open landscape, over long distances mostly in search flight and depending on the circumstances from a control room. The raven walks on the beach, on freshly plowed fields or on rubbish dumps when in sight. When hunting on foot, potential pieces of food are “sampled” with the beak, earth or pieces of wood are cleared to the side, and beak-deep holes are dug into loose earth. Common ravens fly up with snails, nuts and mussels and drop them from a great height onto hard surfaces in order to break them. When looking for carrion, ravens often react to the first shot by approaching them during a hunt , and they also react to the howling of wolves in order to acquire parts of the prey.
When there are disturbances in gray heron or cormorant colonies, ravens use the absence of the nest owner to capture an egg or a small young bird. In seabird colonies breeding on rocky cliffs, ravens are even more active than nest robbers, so if breeding pairs in guillemot colonies fail, the resulting gaps are used immediately. The raven ends up in this gap and harasses one of the directly neighboring breeding birds until it gets up and attacks the raven. The raven backs away. When the guillemot wants to return to its nest, the raven grabs it by the leg and pulls it over the edge of the nest. Both fall, but the raven is more agile in the air, catches itself faster and can grab an egg or chick with its beak and fly away. Breeding kittiwakes are attacked in a similar way , here common ravens throw tufts of grass at the breeding birds in order to drive them away from the nest.
Common ravens like to stay in herds of livestock. In addition to the feed of the cattle, afterbirths and carcasses are used. In Saxony it is said to have been observed that a large proportion of the newborn lambs in a flock of sheep fell victim to ravens. The droppings of cattle, especially calves, are often searched for food. After long periods of rest on the ground, cattle drop their excrement when they stand up. Ravens have been observed several times who pinched lying calves in the hind legs until they stood up. The excrement was eaten by the ravens. In addition, sheep and cattle are occasionally used to sit down to look for insects on the ground.
When there is an oversupply of food, for example in slut areas , ravens bury prey and cover them with tufts of grass or stones in order to use them later. If ravens are observed by potential thieves and notice this, they hide the food somewhere else or they hide dummy food, for example a stone. If, on the other hand, ravens want to act thieving themselves, they watch their conspecifics very closely when they create their hiding places, but try to do this as inconspicuously as possible. Scientists like the behavioral scientist Kurt Kotrschal conclude from this that ravens are able to put themselves in the shoes of others and thus to change perspective.
Gaming behavior
Like other corvids, common ravens often play. Typical games, especially with conspecifics, are "tobogganing" or being rolled down in the snow, on sand dunes or other smooth structures, hanging the head or swinging, the latter occasionally up to the giant rim , balancing and playing with objects.
Reproduction
The onset of sexual maturity in males is not yet known; females are sexually mature at the age of 3 years and usually only breed at the age of four. Common ravens live in monogamous permanent marriage, territory-owning couples can be found in the territories all year round. The partners recognize each other by their voice. The courtship takes place in Central Europe mainly in late winter. It consists of flying games in pairs over the area such as circling together, half-flying rolls and flying in waves, with people often calling out. Courtship also includes mutual feathers, scratching with the beak and mutual feeding.
Depending on what is on offer, the nest is erected on trees, in rock walls or on artificial surfaces, in Central Europe, in recent decades, increasingly on high-voltage pylons, occasionally on exposed buildings. In northern Germany the nests are mainly built on European beech trees , in eastern Germany most often on Scots pines . Both partners build; the mostly round nest consists of quite coarse, dead branches; the hollow is covered with clods of earth, wool, scraps of fur, hair, twine and the like. The nests are often used multiple times, many pairs have one or more alternating nests.
The eggs are laid very early, the earliest laying starts in Central Europe in early to mid-February, most eggs here are started in late February and early March. The clutch consists of two to seven, mostly three to six eggs, which are mostly spotted greenish gray to olive brown on a light green background. The eggs are extremely small in relation to the body weight of the common raven, eggs from northern Germany measure an average of 49.3 mm × 33.1 mm and weigh an average of 27.4 g. Incubation begins with the second egg and the incubation period is 19 to 21 days. The nestlings hatch naked and blind and are pronounced nestlings. Like all songbirds, they lock up to get food. The throat is carmine red in the nestlings, the beak ridges are yellow. The young birds are able to stand at 27 to 29 days. The nestling period is 40 to 42 days, in Central Europe the young birds fly out in mid-April at the earliest, usually in early May.
Age
Information on the average age of wild ravens is not available. The oldest known ringed wild birds were 21 and 23 years old, in captivity the maximum age is 26 years and 28 years, the raven Jakob (1974–2004) of the Innsbruck Alpine Zoo is 30 years old, and the tower ravens are even 44 years old.
hikes
Common ravens are pronounced resident or, at best, line birds in the entire range up to the far north . After leaving their parents' territory, juveniles form flocks and wander more spaciously in search of cheap food sources. Normally, the birds move up to 200 km from the place of birth, larger dispersal distances have only very rarely been detected.
Existence and endangerment
The common raven has been ruthlessly persecuted as an alleged pest of hunting and agriculture for centuries and was exterminated in parts of Central and Western Europe and in the eastern United States. In Europe, the population reached its lowest point around 1940 and the area of distribution its smallest extent. At that time there were only significant stocks in Central Europe in southern Denmark and Schleswig-Holstein , in eastern Poland and in the Alpine region; There were still single pairs in the parts of Lower Saxony and Mecklenburg-Western Pomerania bordering Schleswig-Holstein . With the hunting cessation in the Second World War and the years afterwards, the population began to recover; from around 1960 the species began to repopulate the parts of Central Europe in which it had been exterminated. Population growth and re-expansion continue in western Central Europe. In Belgium , the Netherlands , North Rhine-Westphalia , Thuringia and the Bohemian Forest , repopulation was promoted through reintroduction. As a result, they also immigrated to some earlier regions such as the Emsland and the Grafschaft Bentheim - here after the turn of the millennium.
Common ravens are subject to hunting law in Germany (according to § 2 BJagdG) and have a year-round closed season. The IUCN stated the worldwide population for the year 2003 with about 16 million individuals, the species is considered to be harmless worldwide ( least concern ).
Relationship to other living beings
Common raven and human
Because of their ability to learn, their intelligence and their use of carrion, common ravens became the subject of human legends and myths in a wide variety of contexts very early on. Common ravens have been and are often discussed in literature and poetry. They are portrayed negatively as harbingers of bad luck, as " bad parents ", as thieving, clumsy or dangerous, on the other hand, positively as advisers or helpers to people. Many mentions or popular expressions such as “raven black” refer only to the bird's plumage.
- The Old Testament prophet Elijah is said to have been fed by ravens during his stay in the Kerit valley.
- In the ancient Greek fables, for example those of Aesop , the raven is said to have different character traits such as arrogance or loquacity, as in The Fox and the Raven .
- The Metamorphoses of Ovid , according to the previously gleaming white Raven, Bird had the god Apollo (Phoebus), wearing a bearer of bad news for punishment henceforth black plumage. This is where the myth of the "bad luck messenger" probably originates.
- The raven appears as an important figure in the fairy tales and creation myths of various circumpolar peoples, such as Eskimos and Chukchi . Among the Inuit , the raven Tulukauguk created a beach pea bush from the pod of which the first human slipped. Among the Haida Indians on the North American Pacific coast, the raven stole the light and brought it into the previously dark world.
- Hugin and Munin ("The Thought" and "The Memory") are the two ravens of Odin in Norse mythology.
- The fact that ravens have been kept in the Tower of London for centuries is a modern legend that first appeared at the end of the 19th century.
- In Merseburg is Merseburger Rabe forecast says.
- The raven repeatedly plays a role in German folk tales, for example in The Seven Ravens by the Brothers Grimm .
- A similar motif can be found in the Sorbian legend Krabat , which Měrćin Nowak-Njechorński and Jurij Brězan revised in their novels. Outside of the GDR, the slightly different version of the youth book Krabat by Otfried Preußler became known.
- The raven is the main character in Edgar Allan Poe's poem The Raven .
- The picture story Hans Huckebein, the unlucky raven is one of the works of Wilhelm Busch .
- The poet Christian Morgenstern wrote the poems Der Rabe Ralf and Km 21 , which are about ravens and belong to the gallows songs .
- The medieval music group Corvus Corax has named itself after the Latin name of the common raven.
Some idioms and words go back to the role of the common raven as the most conspicuous "scavenger" in Central Europe. In the Middle Ages they were often to be found at execution sites, which is why it was called "carrion raven and the largest gallows bird", and other raven birds were also referred to as "gallows bird". The swear word “Rabenaas” and the second line of the children's song Hoppe hoppe Reiter (“He falls into the ditch, the ravens eat him”) go back to this fact. Its presence, particularly noticeable in the cold season, made the common raven, like other corvids, a symbol of winter. A common saying alludes to the bird's cunning: "He steals like a raven."
The term "unlucky raven" was probably not initially used for a person persecuted by bad luck, it referred more to the alleged quality of the common raven as a harbinger of misfortune. It is found in this way, for example, in Shakespeare as fatal raven or in the phrase sing a raven's note .
Since young ravens look very clumsy after leaving the nest, the myth arose that ravens were bad parents and would abandon their young prematurely. This can still be found in today's term bad mother again (sometimes Rabenvater , bad parents or by Rabenart ).
As game, the common raven is subject to the special protection of the Federal Hunting Act in Germany and is spared all year round. The hunting and other uses of the common raven were of little importance. Occasionally it was kept tame for entertainment, and in rare cases trained for pickling . Quills used to be used in keel instruments ( harpsichord ) to pluck the strings.
Common ravens and grazing animals
Common ravens are the subject of damage reports from grazing animal owners with corresponding press reports at regular intervals, whereby common ravens are attributed to the killing of lambs, calves and adult cattle. Wherever these reports have been scientifically verified, they have proven to be inaccurate or significantly exaggerated in all cases. In Brandenburg , in view of ongoing press reports, such damage reports were extensively investigated between 1995 and 2000. Of the 391 suckler cow farmers contacted, 13% reported damage caused by ravens, and 22% of 100 sheep farmers. A total of 39 owners were then visited and questioned in more detail. As a result, no damage could be found in the majority of these owners, the damage reports were not reliably traced back to common ravens, only concerned animals that were seriously ill anyway, and some of the damage reports were fictitious. In a total of three cattle and five sheep farmers, the visits revealed evidence of problems actually caused by ravens. These herds, which were then examined in more detail in the course of field studies, were primarily characterized by an attractive food supply for ravens; this consisted of feed from the herd freely accessible to ravens, afterbirths, fresh excrement, especially from young calves, as well as barely viable or dead grazing animals. The field observations showed that ravens in these herds systematically test the health of the grazing animals by pinching or beaking and stop immediately if the grazing animals reacted appropriately. Hack injuries occurred in young animals who were not cared for by their mother, were born weak or ill, in severe births and in young or old animals that were stuck after birth.
Despite the offer of the authorities to have animals possibly killed by ravens examined free of charge with regard to the cause of death, only a very small number of dead grazing animals were given to the examiners; A total of 19 lambs and 16 calves, allegedly killed by ravens, were examined. One of the lambs had a different cause of death, the other 18 without exception had significant damage such as infections, poor nutritional conditions or were not viable after birth. The ravens' chopping marks were made both before and after the lambs died. The calves examined had all died of other causes and were only hacked by ravens after they had died. In the case of many other animal carcasses or photos of them presented for examination, it was evident that ravens were not the cause of the loss; an examination was waived from the outset. A killing of healthy lambs, calves or even cattle could not be proven in any case.
In summary, the authors point out that the damage caused by ravens was caused by, among other things, intensive care of the herd during the young animal births, the early removal of carcasses and weakened animals, making the feed inaccessible by means of appropriate devices and the selection of grazing animal breeds suitable for free-range husbandry can be avoided. In the Emsland / Grafschaft Bentheim area, ravens were widespread when there were still large flocks of sheep. They fed on dead animals and on the afterbirth in the spring.
literature
- Tobias Böckermann: The Return of the Raven - Five decades after the last brood, the common raven has returned to the Emsland and the county of Bentheim, in: Study Society for Emsländische Regionalgeschichte (Ed.): Emsländische Geschichte 18, Haselünne 2011, p. 11– 34.
- Urs N. Glutz von Blotzheim , Kurt M. Bauer : Handbook of the birds of Central Europe. Volume 13, Part III, AULA-Verlag, Wiesbaden 1993, pp. 1947-2022, ISBN 3-89104-460-7 .
- Lars Svensson , Peter J. Grant, Killian Mullarney, Dan Zetterström: The new cosmos bird guide. Kosmos, Stuttgart 1999, ISBN 3-440-07720-9 , p. 336 f.
- Dieter Glandt: Kolkrabe & Co. AULA-Verlag, Wiebelsheim; 2012. ISBN 978-3-89104-760-6
Web links
- Corvus corax in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2008. Accessed on 20 November, 2008.
- Age and gender characteristics (PDF; 3.3 MB) by Javier Blasco-Zumeta and Gerd-Michael Heinze (English)
- Feathers of the common raven
Individual evidence
- ↑ UN Glutz v. Blotzheim and KM Bauer: Handbook of the birds of Central Europe . Vol. 13, Part III, AULA-Verlag, Wiesbaden, 1993: p. 1951 ISBN 3-89104-460-7
- ↑ UN Glutz v. Blotzheim and KM Bauer: Handbook of the birds of Central Europe . Vol. 13, Part III, AULA-Verlag, Wiesbaden, 1993: p. 1952 ISBN 3-89104-460-7
- ↑ Mark Böckle and Thomas Bugnyar: Long-Term Memory for Affiliates in Ravens. In: Current Biology , online pre-publication of April 19, 2012, doi: 10.1016 / j.cub.2012.03.023
- ↑ UN Glutz v. Blotzheim and KM Bauer: Handbook of the birds of Central Europe . Vol. 13, Part III, AULA-Verlag, Wiesbaden, 1993: pp. 1947-1948 ISBN 3-89104-460-7
- ↑ Feldman, CR and KE Omland: Phylogenetics of the common raven complex (Corvus: Corvidae) and the utility of ND4, COI and intron 7 of the β-fibrinogen gene in avian molecular systematics. Zoologica Scripta 34, No. 2, 2005: pp. 145–156
- ^ W. Otto and K. Witt: Distribution and existence of Berlin breeding birds. Berlin Ornithological Report, Volume 12, Special Issue, 2002
- ↑ Ravens become a problem in Saxony. Retrieved March 25, 2019 .
- ↑ a b A. Brehme, D. Wallschläger and T. Langgemach: Common ravens and free-range grazing animals - studies from the state of Brandenburg. In: The ravens in sight. Publication of the Ökologische Jagdverein ÖJV, Rothenburg od Tauber, 2001, pp. 19–32.
- ↑ Behavior: How and why ravens play hide and seek . In: The press . ( diepresse.com [accessed October 7, 2018]).
- ^ Ravens Know When Food-Thieving Rivals Are Watching . In: Live Science . ( livescience.com [accessed October 7, 2018]).
- ↑ Parrots and ravens think differently - derStandard.at. Retrieved October 7, 2018 .
- ↑ UN Glutz v. Blotzheim and KM Bauer: Handbook of the birds of Central Europe . Vol. 13, Part III, AULA-Verlag, Wiesbaden, 1993: S. 1984 ISBN 3-89104-460-7
- ^ European Longevity Records. European Union for Bird Ringing, accessed February 24, 2016 .
- ↑ Richard Wilhelmer - In Memoriam Rabe Jakob. Retrieved December 22, 2019 .
- ↑ UN Glutz v. Blotzheim and KM Bauer: Handbook of the birds of Central Europe . Vol. 13, Part III, AULA-Verlag, Wiesbaden, 1993: p. 1990 ISBN 3-89104-460-7
- ^ Ovid: Metamorphosen , II 531-632
- ↑ M. Wood, J. Sibbick: Geister und Helden der Indianer , Tessloff-Verlag 1982, ISBN 3-7886-0063-2 and on www.sagen.at
- ^ B. Reid, R. Bringhurst: The Raven steals the Light , University of Washington Press, 2003, ISBN 0-295-97524-5
- ↑ a b c Johann Georg Krünitz : Economic Encyclopedia . In: University of Trier
- ↑ Titus Andronicus , II 3, translated by Baudissin as "ravens threatening misfortune"
- ^ Henry VI, III 2
- ^ The Birds Of Shakespeare ( Memento from February 7, 2006 in the Internet Archive )
- ↑ Hall of keyboard instruments: Kiel instruments ( Memento of the original from 23 September 2015 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Deutsches Museum, musical instruments exhibition
- ↑ Hartmuth Brennreiter: kolkraben-toeten-lammer-and-sheep . In: Schwarzwälder Bote from August 6, 2014.
- ^ W. Epple: Rabenvögel . M. Hormann: Pocket book for bird protection. AULA Verlag, Wiebelsheim, pp. 421-439.
