the common raven Picture

another one for my new bird-series...

The Common Raven!

Thanks again to Wikipedia for the following:
The Common Raven (Corvus corax), also known as the Northern Raven, is a large all-black passerine bird in the crow family, with iridescent feathers. Found across the northern hemisphere, it is the most widespread occurring of all corvids, although recent molecular studies may require a split into two or more species. Omnivorous, adaptable and intelligent, it has been able to coexist with humans for thousands of years. Together with the Thick-billed Raven, it is the largest corvid and possibly the heaviest passerine bird.

Though the name "raven" has been applied to several other species of the genus Corvus, the term originally referred to this species. The word itself is similar in many old Germanic languages; the Old English word for a raven was hræfn; in Old Norse it was hrafn and Old High German (h)raban. It is a bird which has been revered and worshipped in cultures as diverse as Norse and Native American, and the subject of art, literature, folklore and symbolism over the centuries. An old Scottish word corby or corbie, akin to the French corbeau, has been used for both this bird and the Carrion Crow. The specific epithet corax/κοραξ is the Greek word for raven.

Description

At maturity, the Raven is between 56 to 69 cm (22 to 27 inches) in length, with a wingspan of 115-130 cm (45-51 inches). Recorded weights range from 689 to 1625 g [8], making it one of the heaviest passerines. It has a longish, strongly graduated tail, mostly black 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 bill is large and slightly curved.

Apart from its greater size, the Raven differs from its cousins the crows by having a larger and heavier beak and wedge-shaped tail. The species has a distinctive, deep, hollow pruk-pruk-pruk call, unlike any other corvid call when known. The species has a very wide and complex vocabulary, includes a high, knocking toc-toc-toc, a dry, grating kraa, a low guttural rattle and some calls almost of a musical nature.

Subspecies

The Common Raven has eight recognized subspecies as followed:

* C. c. corax (nominate race) occurs from Europe eastwards to Lake Baikal region, south to Caucasus and northern Iran. It has a relatively short, arched bill.
* C. c. varius occurs in Iceland and the Faeroes. It is less glossy than C. c. principalis or nominate corax. It is intermediate in size, and the bases of neck feathers are whitish.
* C. c. subcorax occurs from Greece eastwards to north-west India, Central Asia and western China (except Himalayan region). It is larger than the nominate form, but the throat hackles are relatively short. The neck and breast are distinctly brownish (similar to Brown-necked Raven) but obscured by glossy black when the plumage is very fresh. The bases of the neck feathers are variable in colour, often almost whitish.
* C. c. tingitanus occurs in North Africa and the Canary islands. It is the smallest race, with the shortest throat hackles and a distinctly oily plumage gloss. Its bill is short but markedly shout and the culmen is strongly arched. The plumage bleaches dark brown on head and body.
* C. c. tibetanus occurs in the mountains of western China and the Himalayas. It is the largest and most glossy race, with the longest throat hackles. Its bill is large but less imposing than C. c. principalis. The bases of neck feathers are grey.
* C. c. kamtschaticus occurs in north-eastern Asia, intergrading into nominate in Baikal region. It is intermediate in size between C. c. principalis and nominate. It has a distinctly larger and thicker bill than the nominate race.
* C. c. principalis occurs in northern North America and Greenland. It is large in size, with the largest bill. Its plumage is strongly glossed and the throat hackles are well developed.
* C. c. sinuatus occurs in south-central USA and Central America. It is smaller, with a smaller and narrower bill than C. c. principalis.

Molecular studies

A 2005 molecular study reviewed segments of DNA of the Common Raven and found some issues with the current species classification of it and related species. There appear not only to be two clades, a Holarctic and a Californian, but that the related Chihuahuan Raven (C. cryptoleucus) is a sister group to the Californian clade and the Pied Crow (C. albus) is sister to the Holarctic clade.

A recent study shows Canary Island Ravens (Corvus corax tingitanus) have distinct mtDNA.

Distribution and habitat

Common Ravens can thrive in varied climates; indeed this species has the largest range of any member of the genus. They range from the Arctic to the deserts of North Africa, and to islands in the Pacific Ocean. In the British Isles, they are more common in Scotland and the west of Ireland.

In the Faroe Islands a pied colour-morph of this species occurred among all-black birds; known as the Pied Raven, it eventually disappeared in the mid 20th Century, probably due to selective collection for its unusual plumage.

Most Common Ravens prefer wooded areas, with large open land nearby, or coastal regions for their nesting sites and feeding grounds. In some areas of large human population, such as California in the United States, they take advantage of a plentiful food supply and have seen a surge in population.

In Tibet, it is recorded to be found up to 5,000 m altitude and as high as 6,350 m on Mt Everest.

Behaviour

Diet

Common Ravens are highly omnivorous and opportunistic, and have a diet that may vary widely by location, season and serendipity. In some places they are mainly scavengers. They will feed on carrion, as well as the associated maggots and carrion beetles. Plant food includes cereal grains, berries and fruit. They prey on invertebrates, amphibians, reptiles, small mammals and birds. They will consume undigested portions of animal feces, and human food waste. Ravens will store surplus food, especially fat, and will learn to hide such food out of the sight of other Ravens.

Studying the diet of Ravens is made relatively easy by their habit of regurgitating the indigestible parts of their food intake as hard pellets which can be collected and analyzed in the laboratory. Examples of studies of Raven diet are:

* A study of pellets from winter roosts of Ravens in 1966 and 1967, foraging on tundra on the Arctic North Slope of Alaska, showed that about half their energy needs were supplied by predation, mainly of microtine rodents, and half by scavenging, mainly of caribou and ptarmigan carcasses.

* A study in Yellowstone National Park in 2002 showed that Ravens associate with wolves as a kleptoparasitic foraging strategy, following them to scavenge carcasses in winter.

* A 1934 study of Raven stomach contents in Oregon showed that they had mainly or exclusively fed on beetles and maggots when visiting rotting carcasses.

* A 1999-2000 study of Raven diet at and around the Edwards Air Force Base in California, USA, found that Ravens nesting near sources of human garbage included a higher percentage of garbage in their diet, birds nesting near roads consumed more road-killed vertebrates, and those nesting far from these sources of food ate more arthropods and plant material. Fledging success was higher for Ravens utilising human garbage as a food source.

* By way of contrast, a 1984-1986 study of Raven diet in south-western Idaho, an agricultural region, found that cereal grains were the principal constituent of pellets, though small mammals, grasshoppers, cattle carrion and birds were also eaten.

Breeding

Common Ravens usually live ten to fifteen years in the wild, but can be very long-lived, especially in captive or protected conditions. Ravens at the Tower of London have lived for over 40 years. However, life-spans in the wild are considerably less, the longest known lifespan being 13 years for a banded bird. Juveniles begin to court at a very early age, but may not bond for another 2-3 years. Aerial acrobatics and displays of intelligence and ability to provide food are key behaviors of courting Ravens. Once paired, Ravens tend to nest together for life, usually in the same location. The pair will build a nest on a cliff ledge or a tall tree (or a building ledge in cities).

Breeding pairs must have a territory of their own before they begin nest-building and reproduction, and the territory and its food resources will be defended against others. Nesting territories vary in size according to the density of food resources in the area. The nest is made of large sticks and twigs lined with a softer material, such as deer fur. The nest is usually placed on cliff faces and large trees, less frequently in old buildings or on low bushes or on the ground in undisturbed open country.

The female will lay from three to seven pale bluish-green, brown-blotched eggs. Incubation is about eighteen to twenty-one days, by female only. However, the male may 'cover' the young without brooding them as such. Young fledge at thirty-five to forty-two days, and been fed by both partners. The young will stay with the parents for another six months after fledging.

Most egg laying begins in late February, later in higher altitude (e.g. April in Greenland, Tibet) or even earlier in the south of the range (e.g. December in Pakistan).

Like many birds, pairing does not necessarily mandate sexual monogamy, and raven habits show fluidity in this regard.

Vocalization

Like other corvids, Ravens can copy sounds from their environment, including human speech. They have a wide range of vocalizations, which remain an object of interest to ornithologists. An important early work was by Gwinner in 1964, who recorded and photographed his findings in great detail.

Fifteen to thirty categories of vocalization have been recorded for this species. Most are used for social interaction. Some types are alarm calls, chase calls, and flight calls. Non-vocal sounds produced by the common raven include wing whistles and bill snapping. The clapping or clicking has been observed more often in females than males. If a member of a pair of ravens is lost, the remaining raven will make calls which were made by its lost partner in order to get it to return.

Social behaviour

Common Ravens usually travel in mated pairs, however young birds will form flocks as well. One behaviour used by young birds is recruitment, where dominant juvenile ravens will call in a series of loud yells to call other ravens to a food bonanza, usually a carcass. In Ravens in Winter, Bernd Heinrich showed that this behavior evolved to allow the juveniles to outnumber the resident adults, thus allowing the juveniles to feed on the carcass without being chased away by the resident adults.

Intelligence

Popular beliefs about Common Ravens include the notion that they are attracted to shiny objects, but research indicates that juveniles are deeply curious about all new things, and that 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.

Common Ravens have impressed their biologist observers with their apparent intelligence and insight. Experiments have shown that members of the crow family are capable of using tools; an experiment, where some desirable item lay on the bottom of a bottle, showed that some of these birds were able to form a hook to reach the item.

It is a generally held view that Ravens are one of the few, and perhaps only, birds that can count. It is standard practice for ornithologists and photographers using a hide to observe birds nests to take an assistant with them when entering a hide- the birds will usually be agitated at the new presence, but when the assistant leaves, they will assume all is well, unaware that there is still an observer in the hide. It is a widely held belief that Common Ravens are not fooled by this strategy, and are aware that there is still someone present when the assistant has left. However, if enough people enter and exit the hide, the ravens lose count and the observer left in the hide remains undetected.

Relationship with humans

Conservation status and threats

Common Ravens are a widespread bird with an enormous range and are not in danger of extinction. There have been localised declines in some parts of their range due to habitat loss and direct persecution, in other areas their numbers have increased dramatically and they have become agricultural pests. Common Ravens can cause damage to crops such as nuts and grains or can damage livestock, particularly by pecking out the eyes of newborn lambs and calves.

Ravens in popular culture

Throughout its range across the northern hemisphere, the Common Raven has been a popular subject of mythology and folklore in ancient times, through to modern. Cultures as dispersed as the Native Americans, where the raven was revered as Raven, the Trickster god, to the Vikings, to whom in their beliefs the Ravens Hugin and Munin sit on the god Odin's shoulders and see and hear all. There are frequent references in the Bible and further east still it is a figure in Bhutanese myth.

In more recent times the Raven's appearances in literature replace those of mythology and folklore. It frequently appears in the works of William Shakespeare, and, perhaps most famously, the poem The Raven by Edgar Allen Poe. Modern literature, too, has seen ravens within the works of Charles Dickens, Stephen King and George R. R. Martin. The Raven's use in symbolism continues, from countries (Bhutan), territories (Yukon) and football teams (Baltimore Ravens).

btw... The Raven is also a title in the concept-album "Tales of Mystery and Imagination - Edgar Allan Poe" by The Alan Parsons Project... If there is somebody around here who knows a shit about The APP...
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the common raven
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