Alverdens kragefugle
Alverdens kragefugle (corvider)
Denne side indeholder en oversigt over alverdens kragefugle. Formålet er at få et overblik over de kragefugle der findes rundt omkring i verden. Er der fejl eller mangler ved siden, hører jeg gerne nærmere. Skriv til:
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Kurt Starlit
aka Cykelkurt
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Common Raven
Corvus corax corax, Alm. Ravn
The Common Raven (Corvus corax), also known as the Northern Raven, is a large, all-black passerine bird. Found across the northern hemisphere, it is the most widely distributed of all corvids. There are at least eight subspecies with little variation in appearance— although recent research has demonstrated significant genetic differences among populations from various regions. It is one of the two largest corvids, alongside the Thick-billed Raven, and is possibly the heaviest passerine bird; at maturity, the Common Raven averages 63 cm in length and 1.2 kg. Common Ravens typically live about 10 to 15 years in the wild, although lifespans of up to 40 years have been recorded. Young birds may travel in flocks, but later mate for life, with each mated pair defending a territory.
The Common Raven has coexisted with humans for thousands of years and in some areas has been so numerous that it is considered a pest. Part of its success comes from its omnivorous diet; Common Ravens are extremely versatile and opportunistic in finding sources of nutrition, feeding on carrion, insects, cereal grains, berries, fruit, small animals, and food waste.
Some remarkable feats of problem-solving have been observed in the species, leading to the belief that it is highly intelligent. Over the centuries, it has been the subject of mythology, folklore, art, and literature. In many indigenous cultures, including those of Scandinavia, ancient Ireland and Wales, Bhutan, the northwest coast of North America, and Siberia and northeast Asia, the Common Raven has been revered as a spiritual figure or god.
Taxonomy
The Common Raven was one of the many species originally described by Linnaeus in his 18th century work, 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 for "Raven". The specific epithet, corax/???a?, is the Ancient Greek word for "raven" or "crow". The name "raven" has been applied to several other (generally large) species of the genus Corvus, though they are not necessarily closely related to Corvus corax. Some, such as the Australian Raven and Forest Raven, are clearly closer to the other Australian crows. The original raven is now called the Common or Northern Raven.
The modern English word raven has cognates in all other Germanic languages, including Old Norse hrafn and Old High German (h)raban, all which descend from Proto-Germanic *khrabanas. An old Scottish word corby or corbie, akin to the French corbeau, has been used for both this bird and the Carrion Crow. Obsolete collective nouns for a group of ravens (or at least the Common Raven) include "unkindness" and "conspiracy". In practice, most people use the more generic "flock".
Classification
The closest relatives of the Common Raven are the Brown-necked Raven (C. ruficollis) and the Pied Crow (C. albus) of Africa, and the Chihuahuan Raven (C. cryptoleucus) of the North American southwest. While some authorities recognized as many as 11 subspecies, others only recognize eight:
• C. c. corax (the nominate subspecies) occurs from Europe eastwards to Lake Baikal, south to the Caucasus region and northern Iran. It has a relatively short, arched bill. The population in south-western Europe (including the Balearic Islands, Corsica and Sardinia) has an even more arched bill and shorter wings than "typical" nominate, leading some authorities to recognize it as a separate subspecies, C. c. hispanus.Evolutionary history
• C. c. varius occurs in Iceland and the Faroe Islands. It is less glossy than C. c. principalis or nominate corax, is intermediate in size, and the bases of its neck feathers are whitish (not visible at a distance). An extinct color morph found only on the Faroes is known as Pied Raven.
• C. c. subcorax occurs from Greece eastwards to north-west India, Central Asia and western China though not the Himalayan region. It is larger than the nominate form, but has relatively short throat feathers (hackles). Its plumage is generally all black, though its neck and breast have a brownish tone similar to that of the Brown-necked Raven; this more evident when the plumage is worn. The bases of its neck feathers, although somewhat variable in colour, are often almost whitish. (The name C. c. laurencei is sometimes used instead of C. c. subcorax. It is based on the population from Sindh described by Hume in 1873 and is sometimes preferred since the type specimen of subcorax collected by Nikolai Severtzov is possibly a Brown-necked Raven).
• C. c. tingitanus occurs in North Africa and the Canary Islands. It is the smallest subspecies, with the shortest throat hackles and a distinctly oily plumage gloss. Its bill is short but markedly stout, and the culmen is strongly arched. Canary Ravens are browner than the North African Ravens, leading some authorities to treat them as separate subspecies, with the latter maintaining the name C. c. tingitanus and the former known as C. c. canariensis.
• C. c. tibetanus occurs in the Himalayas. It is the largest and glossiest subspecies, with the longest throat hackles. Its bill is large but less imposing than that of C. c. principalis, and the bases of its neck feathers are grey.
• C. c. kamtschaticus occurs in north-eastern Asia, intergrading into the nominate subspecies in the Baikal region. It is intermediate in size between C. c. principalis and C. c. corax and has a distinctly larger and thicker bill than does the nominate race.
• C. c. principalis occurs in northern North America and Greenland. It has a large body and the largest bill, its plumage is strongly glossed, and its throat hackles are well developed.
• C. c. sinuatus, the Western Raven, occurs in south-central USA and Central America. It is smaller, with a smaller and narrower bill than C. c. principalis. Populations in far south-western USA and north-western Mexico (including the Revillagigedo Islands) are the smallest in North America. They are sometimes included in C. c. sinuatus, while other authorities recognize them as a distinct subspecies, C. c. clarionensis.
The Common Raven evolved in the Old World 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 clades: a California 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, 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.
One explanation for these surprising 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 an ice age. 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 recent study of raven mitochondrial DNA showed that the isolated population from the Canary Islands 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
In sunlight, the plumage can display a blue or purple sheen which is due to iridescence. A mature Common Raven ranges between 56 and 78 cm in length, with a wingspan of 100 to 150 cm. Recorded weights range from 0.69 to 2 kg, thus making the Common Raven one of the heaviest passerines. Birds from colder regions such as the Himalayas and Greenland are generally larger with slightly larger bills, while those from warmer regions are smaller with proportionally smaller bills. The bill is large and slightly curved. It has a longish, strongly graduated tail, mostly black iridescent plumage, and a dark brown iris. The throat feathers are elongated and pointed and the bases of the neck feathers are pale brownish-grey. 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. 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. In flight the feathers produce a creaking sound that has been likened to the rustle of silk.
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: typically only 10 to 15 years. The longest known lifespan of a banded wild Common Raven was 23 years, 3 months.
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 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, and as high as 6,350 m on Mount Everest. 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 district of Pakistan and adjoining regions of northwestern India.
Except in Arctic habitats, they are generally resident within their range for the whole year. Young birds may disperse locally.
In the Faroe Islands a now extinct colour-morph of this species existed, known as the Pied Raven.
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 in the United States, they take advantage of a plentiful food supply and have seen a surge in their numbers.
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.
Diet
Common Ravens are omnivorous and highly opportunistic: their diet may vary widely with location, season and serendipity. For example, those foraging on tundra on the Arctic North Slope of Alaska obtained about half their energy needs from predation, mainly of microtine rodents, and half by scavenging, mainly of caribou and ptarmigan carcasses.
In some places they are mainly scavengers, feeding on carrion as well as the associated maggots and carrion beetles. With large-bodied carrion, which they are not equipped to tear through as well birds such as hook-billed vultures, they must wait for the prey to be torn open by another predator or flayed by other means before they can eat themselves. Plant food includes cereal grains, 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 and are considered a threat to the nesting success of the endangered California Condor.
Due to its size, gregariousness and its defensive abilities, the Common Raven has few natural predators. Predators of its eggs include owls, martens, and other ravens. Ravens are quite vigorous at defending their young and are usually successful at driving off perceived threats, including passing humans. There are records of predation by Golden Eagles, with which ravens overlap considerably in range across the Northern Hemisphere. The Eurasian Eagle Owl and the Great Horned Owl have been recorded as grabbing ravens off of their nocturnal perches. Due to the fact that they are potential hazardous prey for raptorial birds, raptors usually must take them by surprise and most attacks are on fledgling ravens. Rarely, large mammalian predators such as lynxes, coyotes, and cougars have attacked ravens. This principally occurs at a nest site and when other prey for the carnivores are scarce. Due to such predators, ravens are highly wary around novel carrion sites and, in North America, have been recorded waiting for American Crows and Blue Jays to approach carrion first before they themselves move in.
Common Ravens nesting near sources of human garbage 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 arthropods 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 south-western Idaho found that cereal grains were the principal constituent of pellets, though small mammals, grasshoppers, cattle carrion and birds were also eaten.
One behavior 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, Bernd Heinrich posited that this behavior 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. Experiments with baits however show that such recruitment behaviour is independent of the size of the bait.
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 behaviors 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 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 to seven pale bluish-green, brown-blotched eggs. Incubation is about 18 to 21 days, by the female only. However, the male may stand or crouch over the young, sheltering but not actually brooding them. Young fledge 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 rarely preyed on by large hawks and eagles, large owls, martens and canids. The adults, which are very rarely predated, 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.
Vocalization
Like other corvids, Ravens can mimic sounds from their environment, including human speech. They have a wide range of vocalizations, which remain an object of interest to ornithologists. 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. 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.
"Crows, ravens, magpies, and jays are not just feathered machines, rigidly programmed by their genetics. Instead, they are beings that, within the constraints of their molecular inheritance, make complex decisions and show every sign of enjoying a rich awareness."The brains of Common Ravens count among the largest of any bird species. Specifically, their hyperpallium is large (see avian pallium). For a bird, they display ability in problem solving, as well as other cognitive processes such as imitation and insight.
—Candace Savage
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'; that is, they have the ability to solve problems presented to them. Many of the Common Raven's problem-solving skills were formerly thought to be instinctive, but it is becoming clear that Common Ravens are actually quite intelligent.
Common Ravens have been observed to manipulate others into doing work for them, such as by calling wolves and coyotes to the site of dead animals. The canines open the carcass, making it 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.
Playful behavior
In recent years, biologists have recognized that 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 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 species who make their own toys. They have been observed breaking off twigs to play with socially.
Conservation and management
Common Ravens are widely distributed and are not currently in danger of extinction; however, there have been some localised declines in populations due to habitat loss and direct persecution. Compared to many smaller Corvus species (such as American Crow), ravens prefer undisturbed montane or forest habitat or rural areas over urban areas. 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 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 behavior 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 are slow-moving. 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.[77] 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, where the population increase in Common Ravens is threatening the vulnerable Steller's Eider (Polysticta stelleri).
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 many post-conversion Western traditions, ravens have long been considered to be birds of ill omen and death, in part because of the negative symbolism of their all-black plumage and the eating of carrion. 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".
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. Ravens have appeared in the works of Charles Dickens, J. R. R. Tolkien, Stephen King, 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, Official Bird of the Yukon territory, and on the Coat of Arms of the Isle of Man (once a Viking colony).
The Baltimore Ravens of the National Football League have had a raven named "Poe" as their official mascot since the Cleveland Browns relocated in 1995.
The modern unisex given name Raven 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 names.
Mythology
Many indigenous peoples of the Pacific Northwest Coast of North America and northeast Asia revered it as a god. In Tlingit and Haida cultures, Raven was both a Trickster and Creator god. Related beliefs are widespread among the peoples of Siberia and northeast 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 of the Bible and it is an aspect of Mahakala in Bhutanese mythology.
In Norse mythology, Huginn (from Old Norse "thought") and Muninn (Old Norse "memory"or "mind") are a pair of ravens that fly all over the world, Midgard, and bring the god Odin information. Additionally among the Norse, Raven banner standards were carried by such figures as the Jarls of Orkney, King Canute the Great of England, Norway and Denmark,[98] and Harald Hardrada. In the British Isles, ravens also were symbolic to the Celts. 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, Bran's head was buried in the White Hill of London as a talisman against invasion.
Tower of London
A legend developed that England would not fall to a foreign invader so 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.
Christianity
In the Judeo-Christian tradition, the raven was the first animal to be released from Noah's ark.
"6 So it came to pass, at the end of forty days, that Noah opened the window of the ark which he had made.
7 Then he sent out a raven, which kept going to and fro until the waters had dried up from the earth.
8 He also sent out from himself a dove, to see if the waters had receded from the face of the ground."
Genesis 8:6-8 NKJV
In Christianity the raven appears throughout the Bible in twelve different verses:
Genesis 8:7,
Leviticus 11:15,
Deuteronomy 14:14,
1 Kings 17:1,
1 Kings 17:4,
1 Kings 17:6,
Job 38:41,
Psalm 147:9,
Proverbs 30:17,
Song of Solomon 5:11,
Isaiah 34:11,
Luke 12:24.
God sends ravens to feed the prophet Elijah in book of 1 Kings 17:1. 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. See Luke 12:24.
ref.:
Common Raven (Wikipedia)
Corvus corax (Google)
Corvus corax (Google Pics)
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Pied Raven
Corvus corax varius, Hvidbroget Ravn
The Pied Raven (Corvus corax varius morpha leucophaeus) was a colour morph of the North Atlantic subspecies of the Common Raven which was only found on the Faroe Islands and has disappeared since the mid twentieth century. It had large areas of white feathering, most frequently on the head, the wings and the belly, and its beak was light brown. Apart from that, it looked like the black birds (morpha typicus).
In Faroese, the bird was called hv??travnur ("White Raven"). Normal individuals of the subspecies varius, which is found on Iceland and the Faroe Islands, already show a tendency towards more extensive white feather bases compared with the nominate subspecies. But only on the Faroes, a mutation in the melanin metabolism would become fixed in the population, causing some birds to have about half of their feathers entirely white. While albinotic specimens sometimes occur in bird populations, the Pied Raven seems not to have been based on such occasional "sports", but on a constantly or at least regularly present part of the local raven population.
As these birds freely interacted and interbred with the black ones which are still found on the islands, they did not constitute a distinct subspecies. However, they illustrate two aspects of population genetics: genetic drift, which in small populations will shift allele frequencies over time (in this case, causing the occasionally-occurring mutation to spread and become a permanent part of the gene pool of ravens on the Faroes), and how a new, distinct subspecies may evolve over time from a distinct part of the population. Had the black and pied ravens mated preferentially with their own morph, in time the pied part of the population might have prevailed, as its coloration probably would have provided better camouflage when preying on seabirds (most of which are also black-and-white).
Description
The first record of the Pied Raven seems to be in the pre-1500 kvæði Fuglakvæði eldra ("The elder ballad of birds") which mentions 40 local species, including the Great Auk. Later, the Pied Raven is mentioned in the reports of Lucas Debes (1673) and Jens Christian Svabo (1781/82). Carl Julian von Graba in 1828 speaks of ten individuals he saw himself and states that these birds, while less numerous than the black morph, were quite common.
D??ðrikur ?? Skarvanesi, the first Faroe painter, painted the Fuglar series, a number of portrayal of birds. On his 18 fuglar ("18 birds"), the animal in the lower right corner can be identified as a Pied Raven. The painting is currently on display in the Listask??lin museum of Faroe art in T??rshavn.
Disappearance
As exemplified by Skarvanesi's painting, which obviously was done from stuffed birds, the Pied Raven was an object of interest to collectors. During the nineteenth century, the pied birds were selectively shot because they could fetch high prices; the s??slumaður (sherriff) of Streymoy, Hans Christopher M??ller once paid two Danish rigsdaler for a stuffed specimen from N??lsoy. Such sums, a healthy amount of money for the impoverished Faroe farmers, made shooting a Pied Raven a profitable enterprise. Additionally, ravens in general were hunted as pests. In the mid nineteenth century, every Faroe male of hunting age was ordered by royal decree to shoot at least one raven or two other predatory birds per year or be fined four skillings. One of the last Pied Raven specimens was shot on November 2, 1902 on Mykines. In the autumn of 1916, another bird was seen at Velbastaður and on Koltur. The last known individual was found in the winter of 1947 on N??lsoy, and disappeared late in 1948. As these last sightings raised widespread interest, it seems probable that after 1948, no Pied Raven has been seen.
The Pied Raven, being a colour variation, only differed in one or very few alleles (as opposed to numerous genes in a true subspecies) from the black birds. The "piebald" allele(s) was or were recessive or (if more than one) only caused the novel coloration if they were all present. This is evidenced by the last sightings which occurred in the absence of a regular breeding population of piebald birds, and the observations of H. C. Müller. Thus, it is not certain that the form is indeed extinct, if one can speak of "extinction" in any but a population genetical sense anyway. Theoretically, the allele(s) could still be present but hidden in black individuals of the subspecies and thus, a Pied Raven could once again be born one day. As the raven population on the Faroes has declined to a few hundred birds at best over the recent decades, this does not seem very likely.
Today, 15 museum specimens of the Pied Raven are known: Six in Copenhagen (Zoologisk Museum), four in New York, two in Uppsala, one in Leiden, one in Braunschweig (Naturhistorisches Museum) and one in Dresden. On June 12, 1995, the Postverk Føroya issued the postal stamp FR 276 which featured a Pied Raven. It was designed by the famous Faroese artist and scientific illustrator Astrid Andreasen.
ref.:
Pied Raven
Pied Raven (Google)
Pied Raven (Google Pics)
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American Crow
Corvus brachyrhynchos, Amerikansk Krage
Kaldes også Common Crow.
The American Crow (Corvus brachyrhynchos) is a large passerine bird species of the family Corvidae. It is a common bird found throughout much of North America. In the interior of the continent south of the Arctic, it is simply called "the crow", as no other such birds occur there on any regular basis.
It is one of several species of corvid that are entirely black, though it can be distinguished from the other two such birds in its range—from the Common Raven (C. corax) by size and behavior and from the Fish Crow (C. ossifragus) by call (but see below). It is also distinguished from the Raven by its smaller, more curved bill than the parallel bill of the raven, and its squared tail.
American Crows are common, widespread and adaptable, but they are highly susceptible to the West Nile Virus. They are monitored as a bioindicator. Direct transmission of the virus from American Crows to humans is not recorded to date, and in any case not considered likely.
Although both the American crow and the Hooded crow strongly resemble in size, structure and behavior, their calls are different. The American crow nevertheless occupies the same role the hooded crow does in Eurasia.
Taxonomy
The American Crow was described by Christian Ludwig Brehm in 1822. Its scientific name means literally "short-billed crow", from Ancient Greek brachy- (ß?a??-) "short-" and rhynchos (??????) "billed".
The Northwestern Crow (C. caurinus) is very closely related to the American Crow. Its ancestors became separated by Ice Age glaciation west of the Rocky Mountains. It is endemic to Pacific temperate rain forests where it all but replaces the American Crow. Only in the Seattle region do they co-occur to any extent. In form the two species are much alike. There is a marked difference in voice.
Subspecies
Four subspecies are recognized. They differ in bill proportion and form a rough NE-SW clinal in size across North America. Birds are smallest in the far west and on the south coast.
Corvus brachyrhynchos brachyrhynchos – Eastern Crow: northeastern United States, eastern Canada and surroundings. Largest subspecies.Description
Corvus brachyrhynchos hesperis – Western Crow: Western North America except arctic north, Pacific Northwest and extreme south. Smaller overall with a proportionally more slender bill and low-pitched voice.
Corvus brachyrhynchos pascuus – Florida Crow: Florida. Mid-sized, short-winged but decidedly long bill and legs.
Corvus brachyrhynchos paulus – Southern Crow: southern United States. Smaller overall, bill also small.
The American Crow is a distinctive bird with iridescent black feathers all over. Its legs, feet and bill are also black. They are 40–50 cm (16–20 in) in length, of which the tail makes up about 40%. Each wing is around 27–34 cm (11–14 in) long. The bill length is on average 5 cm (2 in), varying strongly according to location. Males tend to be larger than females.
The most usual call is a loud, short, and rapid caaw-caaw-caaw. Usually, the birds thrust their heads up and down as they utter this call. American Crows can also produce a wide variety of sounds and sometimes mimic noises made by other animals, including other birds.
Visual differentiation from the Fish Crow (C. ossifragus) is extremely difficult and often inaccurate. Nonetheless, differences apart from size do exist. Fish Crows tend to have more slender bills and feet. There may also be a small sharp hook at the end of the upper bill. Fish Crows also appear as if they have shorter legs when walking. More dramatically, when calling, Fish Crows tend to hunch and fluff their throat feathers.
If seen flying at a distance from where size estimates are unreliable, the distinctly larger Common Ravens (C. corax) can be distinguished by their almost lozenge-shaped tail, their larger-looking heads and of course their strongly solitary habits. They also fluff their throat feathers when calling like Fish Crows, only more so.
Most wild American Crows live for about 7–8 years. Captive birds are known to have lived up to 30 years.
Distribution and habitat
The range of the American Crow extends from the Pacific Ocean to the Atlantic Ocean in Canada, on the French islands of Saint-Pierre and Miquelon, south through the United States, and into northern Mexico. Virtually all types of country from wilderness, farmland, parks, open woodland to towns and major cities are inhabited; it is absent only from Pacific temperate rain forests and tundra habitat where it is replaced by the raven. This crow is a permanent resident in most of the USA, but most Canadian birds migrate some distances southward in winter. Outside of the nesting season these birds often gather in large communal roosts at night.
The American Crow was recorded in Bermuda from 1876 onwards.
Diet
The American Crow is omnivorous. It will feed on invertebrates of all types, carrion, scraps of human food, seeds, eggs and nestlings, stranded fish on the shore and various grains. American Crows are active hunters and will prey on mice, frogs, and other small animals. In winter and autumn, the diet of American Crows is more dependent on nuts and acorns. Occasionally, they will visit bird feeders. The American Crow is one of only a few species of bird that has been observed modifying and using tools to obtain food.
Like most crows, they will scavenge at landfills, scattering garbage in the process. Where available, corn, wheat and other crops are a favorite food. These habits have historically caused the American Crow to be considered a nuisance. However, it is suspected that the harm to crops is offset by the service the American Crow provides by eating insect pests.
Reproduction
American Crows are monogamous cooperative breeding birds. Mated pairs form large families of up to 15 individuals from several breeding seasons that remain together for many years. Offspring from a previous nesting season will usually remain with the family to assist in rearing new nestlings. American Crows do not reach breeding age for at least two years. Most do not leave the nest to breed for four to five years.
The nesting season starts early, with some birds incubating eggs by early April. American Crows build bulky stick nests, nearly always in trees but sometimes also in large bushes and, very rarely, on the ground. They will nest in a wide variety of trees, including large conifers, although oaks are most often used. Three to six eggs are laid and incubated for 18 days. The young are usually fledged by about 35 days after hatching. Predation primarily occurs at the nest site and eggs and nestlings are frequently eaten by snakes, raccoons, ravens and domestic cats. Adults are less frequently predated but face potential attack from Great Horned Owls, Red-tailed Hawks, Peregrine Falcons and eagles. They may be attacked by predators such as coyotes or bobcats at carrion when incautious although this is even rarer.
West Nile Virus
American Crows succumb easily to West Nile virus infection. This was originally a mosquito-borne African virus causing encephalitis in humans and livestock since about 1000 AD, and was accidentally introduced to North America in 1999, apparently by an infected air traveller who got bitten by a mosquito after arrival. It is estimated that the American Crow population has dropped by up to 45% since 1999; the disease runs most rampant in the subtropical conditions which encourage reproduction of its mosquito vectors among which Culex tarsalis is most significant. Mortality rates appear to be higher than those in other birds, causing local population losses of up to 72% in a single season. Because of this, American Crows are a sentinel species indicating the presence of West Nile virus in an area. Crows cannot transmit the virus to humans directly.
Status and conservation
Crows have been killed in large numbers by humans, both for recreation and as part of organized campaigns of extermination.
American Crows are protected internationally by the Migratory Bird Treaty Act of 1918. Despite attempts by humans in some areas to drive away or eliminate these birds, they remain widespread and very common. The number of individual American Crows is estimated by Birdlife International to be around 31,000,000. The large population, as well as its vast range, are the reasons why the American Crow is considered to be of least concern, meaning that the species is not threatened.
ref.:
American Crow (Wikipedia)
American Crow (Google)
American Crow (Google Pics)
American Crow (YouTube)
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Northwestern Crow
Corvus caurinus, Kystkrage
The Northwestern Crow (Corvus caurinus) is an all-black passerine bird of the crow genus native to the northwest of North America. It is very similar to the more western forms of the widespread American Crow (Corvus brachyrhynchos), but it averages slightly smaller (33-41 cm in length) with proportionately smaller feet and a slightly more slender bill. This taxon is reliably identified by range only.
Taxonomy
This species was described by Spencer Fullerton Baird in 1858. The American Ornithologists' Union considers it closely related to the American Crow, and it may be conspecific. Hybrids with American Crow have been reported but not confirmed.
Description
This species plumage is virtually identical to American Crow. A percentage may be distinguished by in-hand criteria such as smaller wing chord and tail length, shorter tarsus, and smaller bill. Percentages increase when sex of animal is known. Like the American Crow, the sexes look the same. Older birds in breeding condition may be reliably sexed by in-hand criteria such as cloacal protuberance (male) or by brood patch (female). Younger birds may not attain breeding condition as they assist at the nest.
Distribution and habitat
This species occurs in coastal regions and offshore islands of southern Alaska, south through British Columbia to Washington state. Beaches and shorelines are the principal forage areas. It can often be seen in and around urban areas.
Diet
Very similar to that of the Fish Crow; the Northwestern Crow eats stranded fish, shellfish, crabs and mussels, and also searches through refuse containers for suitable food items. It has been seen to fly into the air with mussels and drop them onto hard surfaces to break them open. It also regularly eats insects, other invertebrates, and various fruits (especially berries). It raids other birds' nests to eat eggs and hatchlings. It takes handouts and remembers anyone who discards food. It is known to soak pieces of bread in water.
Predators
An incomplete list includes cats, raccoons, raptors and ravens. The crows often gather in large groups to mob these predators.
Nesting
Generally solitary, but sometimes built in association with a few other individuals in small, loose colonies in trees or sometimes large bushes. Very rarely, it will nest on cliffs in a recess or even on the ground in a remote area if overhung by a rock for shelter. It is a typical crow nest with 4-5 eggs usually laid.
Voice
The voice is very varied, and many types of call are made, but the most common are usually described as a high pitched "caw" and the sound of a cork coming out of a bottle. A "wok-wok-wok" is given by a bird in flight if straggling behind the group, and various clicks and mechanical sounding rattles are also heard.
ref.:
Northwestern Crow (Wikipedia)
Northwestern Crow (Google)
Northwestern Crow (Google Pics)
Northwestern Crow (YouTube)
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Sinaloa Crow
Corvus sinaloae, Sinaloakrage
The Sinaloa Crow (Corvus sinaloae) is a crow native to western Mexico. Visually, it is nearly identical to and the same length (34-38 cm) as the Tamaulipas Crow (Corvus imparatus). It has the same purple-glossed, silky, black plumage with a black bill, legs, and feet. The two species differ markedly in voice.
It occurs on the Pacific slope from southern Sonora south to central Nayarit. {Also seen farther south in Manzanillo, Colima, as of 2011} (This range is shared by a number of "Northwest Mexican" endemic birds, like Elegant Quail, Purplish-backed Jay, and Rufous-bellied Chachalaca.) The crow inhabits coastal regions where it forages on the seashore, semi-desert, open woodlands, river banks and hills up to 300 metres or more. It is very common around coastal towns and villages.
Food is taken both on the ground and in trees. On the seashore it can be found turning over objects to find its food and it will take a wide range of invertebrates such as small shellfish, crabs, and insects. Fruits of many types are also taken and eggs and nestlings are also on the menu when opportunity arises.
Often, this bird will nest in a thorny tree or a tall coconut palm where its nest is said to be similar to the American Crow though smaller.
The voice is radically different from the Tamaulipas Crow in that it is quite high-pitched, jay-like, and clear: "ceow". That of the Tamaulipas Crow is a surprisingly low, gruff, frog-like croak.
Another species, the Fish Crow Corvus ossifragus from the southeastern seaboard of the United States is also considered genetically very close to both this species and the Tamaulipas Crow Corvus imparatus and the three are now considered a "Superspecies".
Other names: When lumped with the Tamaulipas Crow, the more inclusive taxon was called Mexican Crow.
ref.:
Sinaloa Crow (Wikipedia)
Sinaloa Crow (Google)
Sinaloa Crow (Google Pics)
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Chihuahuan Raven
Corvus cryptoleucus, Chihuahuaravn
Kaldtes tidligere American White-necked Raven
The Chihuahuan Raven (Corvus cryptoleucus), is a species of bird in the family Corvidae that is native to the United States and Mexico. It was formerly known as the American White-necked Raven, and has the proportions of a Common Raven with a heavy bill, but is about the same size as a Carrion Crow, or slightly larger than the American Crow (44–51 cm long). The plumage is all-black with a rich purple-blue gloss in good light. The nasal bristles extend farther down the top of the bill than in any other Corvus species to about two-thirds the length. The base of the neck feathers are white (seen only when ruffled in strong wind). The bill, legs and feet are black.
Distribution and habitat The Chihuahuan Raven occurs in the Southwestern and Midwestern United States and northern Mexico, including southeastern Arizona, southern New Mexico, southeastern Colorado, western Kansas, western Oklahoma, and southern and western Texas.
Diet
It feeds on cultivated cereal grains, insects and many other invertebrates, small reptiles, carrion and scraps of human food, cactus fruits, eggs and nestlings.
Nesting
The nest is built in either trees, large shrubs or sometimes even in old buildings. There are usually 5-7 eggs laid relatively late in the year during May so as to take advantage of the insect food for their young in their more arid environment.
Voice
The voice is similar to the Common Raven with "pruk-pruk" sounds and other croaks but is not as deep in tone or as varied in range.
Taxonomy
A 2005 molecular study reviewed segments of DNA of the Common Raven and found that Chihuahuan Raven are genetically nested within Common Ravens based on mitochondrial DNA. That is, Common Ravens from the California Clade are more similar in mtDNA to Chihuahuan Ravens than they are to Common Ravens in the Holarctic Clade.
ref.:
Chihuahuan Raven (Wikipedia)
Chihuahuan Raven (Google)
Chihuahuan Raven (Google Pics)
Chihuahuan Raven (YouTube)
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Tamaulipas Crow
Corvus imparatus, Taumalipaskrage
Kaldtes tidligere Mexican Crow.
The Tamaulipas Crow (Corvus imparatus) a crow found in northeastern Mexico and some of southern Texas.
Description
It is a relatively small and sleek looking crow, 34–38 centimetres in length. It has very glossy dark, bluish plumage, which appears soft and silky. The bill is quite slender and black, as are the legs and feet. The Chihuahuan Raven, a much larger and very different bird, is the only crow it commonly occurs alongside.
Taxonomy
The Sinaloan Crow (Corvus sinaloae) appears to be genetically extremely close to this bird and can be considered the western form of it though the voice is quite different, indeed a third species, the Fish Crow (Corvus ossifragus) of the southeastern United States appears to be very closely related to them also and the three may be considered a superspecies.
Distribution and habitat
Occurring in a relatively small area in northeastern Mexico, it inhabits near desert scrub and bushland and includes farms, small towns and villages in its range. It also occurs in more humid woodland in open areas but does not appear to be found in the higher mountains or along the seashore. It is a sociable bird often forming large flocks, moving together in close groups. Its northern range reaches Brownsville in southern Texas where it has been known to nest.
Diet
Food would appear to be mainly insects taken on the ground though eggs and nestlings are taken in trees as well as many fruits and berries.
Nesting
The nest is similar to the American Crow but smaller and is built in a tree or large bush.
Voice
The voice of this crow is unusual and unlike most other species of the genus Corvus. It has a low croaking sound rather like a frog and a call that is described as a soft "gar-lik".
ref.:
Tamaulipas Crow (Wikipedia)
Tamaulipas Crow (Google)
Tamaulipas Crow (Google Pics)
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Fish Crow
Corvus ossifragus, Fiskekrage
The Fish Crow (Corvus ossifragus) is a species of crow that is associated with wetland habitats in the eastern and southeastern United States.
Taxonomy
The Fish Crow was first described by Alexander Wilson in 1812. The latest genetic testing now seems to indicate that this species is close to the Sinaloan Crow (Corvus sinaloae) and the Tamaulipas Crow (Corvus imparatus), and not as close to the American Crow (Corvus brachyrhynchos) as outward signs would suggest
Description
The Fish Crow is superficially similar to the American Crow but is smaller (36–41 cm in length) and has a more silky smooth plumage by comparison. The upperparts have a blue or blue-green sheen, while the underparts have a more greenish tint to the black. The eyes are dark brown. The differences are often only really apparent between the two species when side by side or, when heard calling. The bill is usually somewhat slimmer than the American Crow, but is only readily distinguishable if both species are seen together.
Visual differentiation from the American Crow is extremely difficult and often inaccurate. Nonetheless, differences apart from size do exist. Fish crows tend to have more slender bills and feet. There may also be a small sharp hook at the end of the upper bill. Fish crows also appear as if they have shorter legs when walking. More dramatically, when calling, fish crows tend to hunch and fluff their throat feathers.
The voice is the most outwardly differing characteristic for this species and other American crow species. The call of the Fish Crow has been described as a nasal "ark-ark-ark" or a begging "waw-waw". Birders often distinguish the two species (in areas where their range overlaps) with the mnemonic aid "Just ask him if he is an American Crow. If he says "no", he is a Fish Crow." referring to the fact that the most common call of the American Crow is a distinct "caw caw", while that of the Fish Crow is a nasal "nyuh unh".
Distribution and habitat
This species occurs on the eastern seaboard of the United States from the state of Rhode Island south to Key West, and west along the northern coastline of the Gulf of Mexico and follows many river systems inland for quite some distance. Coastal marshes and beaches are frequented, also rivers, inland lakes and marshes, river banks, and the land immediately surrounding all.
Diet
Food is taken mainly from the ground and even in shallow water where the bird will hover and pluck food items out of the water with its feet. Small crustaceans such as crabs, shrimps, other invertebrates, stranded fish and live fish if the situation favors their capture, eggs and nestlings, small reptiles and fruits of many trees, peanuts and grains, human scraps where available.
Breeding
The nest is usually built high in a tree and is often accompanied in nearby trees with other nests of the same species forming small, loose colonies. There are usually 4-5 eggs laid. Pale blue-green in colour, they bear blotches of olive-brown.
ConservationThis species appears to be somewhat more resistant to West Nile Virus than the American crow. Survival rates of up to 45% have been reported for fish crows, compared with near zero for the American species.
ref.:
Fish Crow (Wikipedia)
Corvus ossifragus (Google)
Corvus ossifragus (Google Pics)
Corvus ossifragus (YouTube)
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White-necked Crow
Corvus leucognaphalus, Hispaniolakrage
The White-necked Crow (Corvus leucognaphalus) is the largest (42–46 centimetres in length) of the four Caribbean crow species. Two other species, the Cuban Crow (Corvus nasicus) and the Jamaican Crow (Corvus jamaicensis), appear to be very closely related to it sharing several key morphological features. The fourth species from this region, the Palm Crow (Corvus palmarum), would appear to be a later arrival (at least in evolutionary terms) and shows affinities with the Fish Crow (C. ossifragus) of North America and two Mexican species.
A stocky bird, this forest crow is now found principally on the large island of Hispaniola that comprises the countries of Dominican Republic and Haiti. It was also found on Puerto Rico but is now considered to be extinct on that island since the early 20th Century due to considerable forest clearance and hunting. It inhabits both lowland and mountain forest and unlike the related Cuban Crow, does not appear to tolerate areas that have been cleared for farming. It often flies high over the forest canopy and soars on thermals unlike the conspecific Palm Crow which rarely if ever soars.
Description
The overall appearance is black with a bluish-purple gloss in good light. The black bill is long and deep and curves gently downward to the tip giving the bird a large headed appearance. The nasal bristles do not quite cover the nostrils unlike the majority of species in this genus. There is a patch of dark grey bare skin behind the eye and the base of the lower mandible has a bare strip of the same coloured skin. The iris is a distinctive reddish ochre in colour, and the legs and feet are black.
Diet
The diet is typical of most forest crows, comprising a large amount of fruit but a degree of invertebrate food is also taken especially when feeding young. Small vertebrate prey has also been found in the stomachs of collected birds including small native toads and nestlings. It can almost certainly be presumed that bird eggs are also taken when found.
Reproduction
The nest is always solitary and built high in a tall tree though little else concerning their breeding has as yet been recorded.
Voice
The voice of the White-necked Crow is quite remarkable and consists of a series of liquid bubbling sounds, squawking and babbling mixed with sweet and harsh notes including some that sound like the Common Raven, Corvus corax.
ref.:
White-necked Crow (Wikipedia)
White-necked Crow (Google)
White-necked Crow (Google Pics)
UK Name (YouTube)
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Palm Crow
Corvus palmarum, Palmekrage
The Palm Crow (Corvus palmarum) is a relatively small black bird in the crow family that occurs mostly on the large Caribbean island of Hispaniola, itself divided into the two countries of Dominican Republic and Haiti. It was formerly quite frequent on Cuba but has become severely reduced in number and may be almost extinct there. This form is slightly smaller and is usually separated as a sub-species called Corvus palmarum minutus. Both forms are usually now given the respective common names of Hispaniolan Palm Crow and Cuban Palm Crow to distinguish them.
Both forms appear to be closely related to the Fish Crow (C. ossifragus) of the East Coast of the United States and also two smaller species, the Tamaulipas Crow (C. imparatus) and Sinaloan Crow (C. sinaloae) of Mexico and forms a species group with them.
The Dominican local name for the palm crow is cao, which is onomatopoeic of the simple and repetitive call of this bird. There it is locally common, mainly in mountain pine forests and also around the area of the lake Enriquillo.
ref.:
Corvus palmarum (Wikipedia)
Corvus palmarum (Google)
Corvus palmarum (Google Pics)
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Cuban Crow
Corvus nasicus, Cubakrage
The Cuban Crow (Corvus nasicus) is one of four species of crow that occur on a few key islands in the Caribbean. It is closely related to the White-necked Crow (C. leucognaphalis) and Jamaican Crow (C. jamaicensis), with which it shares similar features. The fourth Caribbean crow, the Palm Crow (C. palmarum), is a later arrival in evolutionary terms and shows characteristics more akin to North American species such as the Fish Crow (C. ossifragus), which it is probably closely related to.
A stocky, medium sized (40–42 centimetres in length) forest crow, this sociable bird can be found quite commonly over most of the large island of Cuba and on the nearby Isla de la Juventud in woodland and areas that have been cleared for agriculture. It is frequently found around farms and villages where it seems to have adapted quite well to living in relatively close contact with man.
The bill of this species is long and deep with a gentle curve towards the tip giving a large headed profile. The nasal bristles sweep forward then upward and frequently reveal the nostrils which are hidden in almost all other members of the genus Corvus. There is a patch of dark grey bare skin behind the browinsh-red eye and at the base of the lower mandible. The black plumage has a bluish-purple gloss in good light. The bill, legs and feet are black.
Food consists of fruit and insects though it does appear to take human food readily and will scavenge for scraps where the opportunity arises. Large noisy flocks can be seen feeding in trees and it will also readily feed on the ground especially where grain and other seeds have been spilt or left unprotected on the surface of a field.
The voice is quite remarkable and is rather un-crow like, with strange liquid bubbling notes and high ringing sounds produced in various combinations. It also produces a thin screeched "aaaaauh" that rises in inflection.
The nest is built in tall trees, though little further information about breeding is recorded as yet.
ref.:
Cuban Crow (Wikipedia)
Cuban Crow (Google)
Cuban Crow (Google Pics)
Cuban Crow (YouTube)
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Jamaican Crow
Corvus jamaicensis, Jamaicakrage
The Jamaican Crow, Corvus jamaicensis is a comparatively small crow species (35–38 cm in length). It shares several key morphological features with two further West Indian species, the Cuban Crow, Corvus nasicus and the White-necked Crow, Corvus leucognaphalus of Hispaniola which are almost certainly very closely related to it.
As its name suggests, this species is found on the moderately sized island of Jamaica where it inhabits woodland mixed with cleared areas and can be frequently found in larger gardens also. Though primarily a bird of hill and mountain forest, it comes down to lower elevations during the dry season where it is more likely to be seen.
The overall appearance of this species is of a sooty-grey bird, not at all glossy like its near relatives though it does possess a similar dark grey patch of naked skin just behind the eye and a smaller naked patch at the base of the bill. The bill itself is slate-grey and quite deep, tapering to a sharp point. The nasal bristles are relatively sparse usually leaving the nostrils on view. The iris is either grey-brown or red-brown, possibly depending on age. Legs and feet are black.
Another forest crow by nature, its food requirements contain a significant proportion of fruit taken from trees either in pairs or small groups. It also probes under bark and leaf litter for small invertebrates etc. and it is known to raid other birds nests of both eggs and nestlings.
The nest itself is usually built in a tall tree though this species may well use tree holes also as a possible nesting option although little further information is as yet recorded for this species and its breeding habits.
The voice, like its two nearest relatives is very distinctive and consists of various jabbering and bubbling sounds (thus its common Jamaican Patois name, Jabbering Crow), but also including a more crow-like "craa-craa" sound on occasion.
ref.:
Jamaican Crow (Wikipedia)
Jamaican Crow (Google)
Jamaica Crow (Google Pics)
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Pied Crow
Corvus albus, Broget Krage / Hvidbrystet Ravn
The Pied Crow (Corvus albus) is a widely distributed African bird species in the crow genus.
Structurally, the Pied Crow is better thought of as a small crow-sized Raven, especially as it can hybridise with the Somali Crow (Dwarf Raven) where their ranges meet in the Horn of Africa. Its behaviour, though, is more typical of the Eurasian Carrion Crows, and it may be a modern link (along with the Somali Crow) between the Eurasian crows and the Common Raven.
Description
It is approximately the size of the European Carrion Crow or a little larger (46–50 cm in length) but has a proportionately larger bill, slightly longer tail and wings, and longer legs. As its name suggests, its glossy black head and neck are interrupted by a large area of white feathering from the shoulders down to the lower breast. The tail, bill and wings are black too. The eyes are dark brown. The white plumage of immature birds is often mixed with black. It resembles the White-necked and Thick-billed Ravens but has a much smaller bill.
Measurements
Length 46 – 52 cm
Wing 328 to 388 mm
Weight 520 g
Identification
In southern Africa the range overlaps with the White-necked Raven. The Pied Crow is slightly smaller and has a white chest and belly with a black beak compared to the black chest and belly of the larger White-necked Raven which also has a white tip of the beak. It is larger than the Black Crow.
Voice
The voice is described as a harsh "ar-ar-ar-ar" or "karh-karh-karh".
ref.:
Pied Crow (Wikipedia)
Fugleobs
2011.Sept.24-29
Ravne
På en fornøjelsestur til Berlin besøgte vi den zoologiske have. Den almindelige Ravn (Corvus corax) eller andre kragefugle finder man ikke her, men til gengæld sad et par afrikanske ravnefugle i en særlig afdeling for rov- og andre store fugle. Hvor godt eller dårligt fuglene havde det, kan diskuteres, ihvertfald havde en af fuglene fået viklet det ene ben ind i noget tråd, som tydeligvis voldte irritation og smerte. Flere af havens ansatte gik forbi buret uden tilsyneladende at være anfægtet af fuglens situation.
Schildrabe (Corvus albus), Pied Crow, Broget Krage / Hvidbrystet Ravn
Schildrabe (Corvus albus), Pied Crow, Hvidbrystet Ravn er en afrikansk kragefugl, som er udbredt over midt- og sydafrika. I farvetegningen kan den minde om en husskade, selv om den i kropsbygning og størrelse snarere ligner en alm. (grå)krage.
Schildrabe
Schildrabe tavle
Pied Crow (Google)
Pied Crow (Google Pics)
Pied Crow (YouTube)
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White-necked Raven
Corvus albicollis, Corvus albicilla, Hvidhalset Ravn
The White-necked Raven, Corvus albicollis, is somewhat smaller (50–54 cm in length) than the Common Raven or indeed its nearest relative, the Thick-billed Raven C. crassirostris.
It has a much shorter tail and a deeper bill with a white tip that is strongly arched (almost as much as the Thick-billed Raven). Though predominantly black, the throat, breast and neck are a blackish-brown in colour, with a faint purple gloss. There is a large patch of white feathers on the back of the lower neck.
Soars well with shallower wingbeats than other Corvidae.
Length 50 - 54 cm
Wing 376 - 430 mm
Weight 762 - 865 g
Voice
Often described as a raven with a sore throat, it has very similar calls to the Common Raven, but with a more husky note. It has a croak like the raven but with a more whispering note added.
Distribution and habitat
occurs in eastern and southern Africa in open, mountainous country. It is quite commonly found in small towns and villages as long as there are mountains or hills for roosting and nesting relatively nearby.
Behaviour
Most of this birds food is obtained from the ground, but it will take food from trees also. It has been seen to drop a tortoise from a height on to hard ground, preferably on rocks, and then swoop down to eat it, or even pick it up again if not sufficiently broken. White-necked Ravens will also readily take carrion from road kills. Fruit, grain, insects, small reptiles, peanuts and human food are also readily taken and if not persecuted, will forage in back yards and gardens quite openly.
Often in the company of other scavengers such as kites or vultures.
Nests are a bowl of sticks lined with grass hair and wool found mainly on a cliff ledge but will occasionally nest in a tree. There are usually 3-5 eggs laid.
ref.:
White-necked Raven (Wikipedia)
White-necke d Raven (Google)
White-necked Raven (Google Pics)
White-necked Raven (YouTube)
Geierrabe (Corvus albicollis), White-necked Raven, Hvidhalset Ravn
Geierrabe med den typiske hvide nakke. Bemærk også de lyse næbspidser.
Geierrabe, den hvidhalsede ravn, hører hjemme i det østlige og sydlige Afrika. Her lever den på samme måde som vores hjemlige Ravn (Corvus corax) af alskens ting og sager, f.eks. insekter, mus, rotter og frugt. Desuden tager den for sig af retterne på de menneskeskabte affaldspladser.
stort billede
Geierrabe tavle
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Cape Crow
Corvus capensis, Afrikansk Råge
Kaldes også Black Crow
The Cape Crow or Black Crow (Corvus capensis) is slightly larger (48–50 cm in length) than the Carrion Crow and is completely black with a slight gloss of purple in the feathers. It has proportionately longer legs, wings and tail too and has a much longer, slimmer bill that seems to be designed for probing into the ground for invertebrates. The head feathers have a coppery-purple gloss and the throat feathers are quite long and fluffed out in some calls and displays.
Distribution and habitat
This species occurs in two large separate regions of the African continent. One form ranges from the Cape at the southern tip of Africa up to southern Angola and across to the east coast of Mozambique. The other population occurs in a large area from Sudan, Ethiopia, Tanzania and Kenya in central east Africa. The more northern population is on average slightly smaller than the southern. It inhabits open grassland, moorland, agricultural areas with some trees or woodland in the vicinity for nesting. It seems to thrive especially in agricultural areas.
Diet
As far as feeding is concerned, it eats grain and other seeds, invertebrates which it digs for with powerful downward stabs of its long bill. It opens Maize before they are fully ripe, bulbs and fleshy roots of certain plants, frogs and small reptiles, fruits and berries. It takes the eggs and chicks of ground nesting birds and has been known to kill birds of up to a pound in weight (especially domestic poultry). It turns over the droppings of mammals for insects.
Nesting
Nesting is always in trees, usually near the top. It has been known to nest in shrubs but much less frequently. There are usually 3-4 eggs incubated over 18–19 days and fledged by around 38 days. Usually only 3 nestling's ever surviving.
Voice
The voice is describes as a "krrah.....krrah.....krrah" or a quicker "kah-kah-kah". It also make very loud, liquid bubbling sounds that carry quite a distance and also gives throaty chuckles. There is evidence that vocal mimicry is practiced too.
ref.:
Cape Crow (Wikipedia)
Cape Crow (Google)
Cape Crow (Google Pics)
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Thick-billed Raven
Corvus crassirostris, Tyknæbbet Ravn
The Thick-billed Raven (Corvus crassirostris), a Corvid from the Horn of Africa, shares with the Common Raven the distinction of being the largest in the Corvid family, and indeed the largest of the bird order Passeriformes (perching birds). They measure 60-64 cm (24-25 in) in length and weigh 1.5 kg (3.3 lbs). It has a very large bill that is laterally compressed and is deeply curved in profile giving the bird a very distinctive appearance. This bill is black with a white tip and has deep nasal grooves with only light nasal bristle covers.
This raven has very short feathers on the head, throat and neck, which on the throat and upper breast have an oily brown gloss. The rest of the bird is glossy black except for a distinctive white patch of short feathers on the nape and onto the neck.
Distribution and habitat
Its range covers Eritrea, Somalia and Ethiopia; its habitat includes mountains and high plateau between elevations of 1500 to 3400 metres.
Diet
The Thick-billed Raven is omnivorous, feeding on grubs, beetle larvae from animal dung, carrion, scraps of meat and human food. It has been seen taking standing wheat. When seeking food from dung, it has been seen using a distinct scything movement to scatter the dung and extract the grubs.
Nesting
It nests in trees and on cliffs, apparently building a stick nest like the similar White-necked Raven. It lays three to five eggs.
Voice
Its calls include a harsh nasal croak, a low wheezy croak, a "raven-raven", and sometimes a "dink,dink,dink" sound.
ref.:
Thick-billed Raven (Wikipedia)
Thick-billed Raven (Google)
Thick-billed Raven (Google Pics)
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Brown-necked Raven
Corvus ruficollis, Ørkenravn
Kaldes også Brunhalset Ravn
The Brown-necked Raven (Corvus ruficollis) is a larger bird (52–56 cm in length) than the Carrion Crow though not as large as the Common Raven. It has similar proportions to the common raven but the bill is not so large or deep and the wings tend to be a little more pointed in profile. The head and throat are a distinct brownish-black giving the bird its English name, while the rest of the plumage is black glossed with purple, blue or purplish-blue. The feathers of this species often fade quite quickly to a brownish black (even the truly black feathers) and the bird can look distinctly brown by the time it moults. The feet, legs and bill are black. The Dwarf Raven was formerly considered a subspecies (Corvus ruficollis edithae) but this bird now appears to be closer to the Pied Crow (C. albus) than this species. Hybrids between this species and the Pied Crow seem to reinforce their close relationship. This species is found principally in Somalia and neighbouring areas.
This species has a wide range across virtually the whole of North Africa, down as far as Kenya, the Arabian peninsula and up into the Greater Middle East and southern Iran. It lives in a predominantly desert environment visiting oases and palm groves.
Food consists of a wide range of items including carrion, snakes, locusts and other grasshoppers, stranded fish (in coastal areas), grain stolen from bags, dates and other fruits. It is quite fearless when not persecuted but is quick to become wary and shy if too much attention is paid to it. A 2009 Israeli study showed the species to cooperatively hunt lizards, with birds blocking exits while others hunted.
The nest is very much like the Common Raven's, and may be found in trees, on cliffs or in old and ruined buildings. The Dwarf Raven seems to prefer thorn trees for its nest building. There are usually 4-5 eggs laid and incubated over 20–22 days. The young usually leave the nest by the 37th or 38th day and can fly well by 42–45 days.
The voice is very similar to the Common Raven's consisting mainly of croaks, though higher in pitch; and a harsh "karr-karr-karr" very much like a Carrion Crow too. In flight, it will utter a "kuerk-kuerk" call.
ref.:
Brown-necked Raven (Wikipedia)
Brown-necked Raven (Google)
Brown-necked Raven (Google Pics)
Brown-necked Raven (YouTube)
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Somali Crow
Corvus edithae, Somaliravn
Kaldes også Dwarf Raven
The Somali Crow or Dwarf Raven, Corvus edithae is approximately the size (44-46 cm in length) of the Carrion Crow, Corvus corone but with longer bill and somewhat more brownish cast to the feathers especially when worn.
This species occurs principally in Somalia, Djibouti, the Ogaden and the Northern Frontier District in the Horn of Africa, and can be distinguished from larger Brown-necked Raven C. ruficollis by its call (voice) and differences in its behaviour.
Though previously considered a subspecies of the larger C. ruficollis, it has recently been elevated to species status, rather like the Hooded Crow Corvus cornix from its near relative the Carrion Crow.
This species is now thought to be closer to the Pied Crow C. albus especially in its behaviour than to the Brown-necked Raven. Hybrid birds between the Pied Crow and the Somali Crow (Dwarf Raven) appear to reinforce this close relationship where the two species meet.
The nest is a raven-like bulky structure set in either a lone tree or on telegraph poles. It will nest on cliffs in coastal regions or areas where trees are unavailable. The 3-5 eggs are laid in April and early May though little further information is recorded on their subsequent development.
The voice is described as a harsh "caw" rather like the Rook, Corvus frugilegus of Eurasia.
ref.:
Somali Crow (Wikipedia)
Somali Crow (Google)
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Fan-tailed Raven
Corvus rhipidurus, Korthalet Ravn
The Fan-tailed Raven is completely black including bill, legs and feet and the plumage has a purplish-blue gloss in good light. Worn plumage is slightly coppery-brown. The base of the feathers on the upper neck are white and only seen if the bird is inspected or a strong gust blows them the wrong way. The throat hackles are shorter than in most other ravens.
The voice is described as guttural croaks mixed with the sound of frog-call.
Distribution and habitatIt
Occurs in the Middle East, North Africa, Arabia, and south to Sudan and Kenya. It also ranges across the Air Massif in the southern Sahara. It lives in desert or open dry country that includes crags for nesting. It is one of the most aerial of birds traveling huge distances in search of food, its large wings being adapted to gliding on thermals in a rather vulture-like way.
Diet
Food is invariably taken on the ground and includes all manner of insects and other invertebrates, grain taken from animal dung, carrion and scraps of human food. It has also been seen taking skin parasites from camels and, where not persecuted, scavenges around rubbish dumps and camp sites. Fruits of all types are eaten readily. It soars and plays in thermals even more so than other Raven species and often associates with the Brown-necked Raven roosting in the same tree as it.
Nesting
This species nests on rock ledges and in cavities in cliffs though very rarely in Somalia it has been known to nest in trees. There are usually 2-4 eggs laid. The Great-spotted Cuckoo (Clamator glandarius) sometimes uses this species as a brood host.
ref.:
Fan-tailed Raven (Wikipedia)
Corvus rhipidurus (Google)
Corvus rhipidurus (Google Pics)
Corvus rhipidurus (YouTube)
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Slender-billed Crow
Corvus enca, Tyndnæbbet Krage
The Slender-billed Crow (Corvus enca) is a species of bird in the Corvidae family. Its eastern populations are called Violaceous Crow and sometimes separated as Corvus violaceus.
It is found in Brunei, Indonesia, Malaysia, and the Philippines. Its natural habitats are subtropical or tropical moist lowland forests and subtropical or tropical mangrove forests.
ref.:
Slender-billed Crow (Wikipedia)
Slender-billed Crow (Google)
Slender -billed Crow (Google Pics)
Lydoptagelser (Slender-billed Crow)
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Flores Crow
Corvus florensis, Floreskrage
The Flores Crow (Corvus florensis) is a species of bird in the Corvidae family. It is endemic to Indonesia.
Its natural habitats are subtropical or tropical dry forests and subtropical or tropical moist lowland forests. It is threatened by habitat loss.
Justification
This rather diminutive crow has a very small population, which is subject to a continuing decline in the face of rampant deforestation on its island home. It thus qualifies as Endangered.
Identification
40 cm. Medium-sized, forest-dwelling crow. Plumage all black, dark iris. Feathering extends halfway along ridge of bill. Similar spp. Large-billed Crow C. macrorhynchos is much larger with more massive bill.
Voice
High-pitched, downwardly inflected cwaaa or cawaraa. Also waak repeated 1-3 times, resonant popping or gurgling and wheezing contact call.
Distribution and population
Corvus florensis is endemic to the islands of Flores and Rinca1, Nusa Tenggara, Indonesia, where it is known chiefly from the lowlands in the western half of Flores. It seems likely that it has always been relatively uncommon, although locally frequent in undisturbed habitat. Overall it is acknowledged to occur only at low densities, with most encounters involving single birds, and appears to have declined.
ref.:
Flores Crow (BirdLife)
Flores Crow (Google)
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Brown-headed Crow
Corvus fuscicapillus, Brunhovedet Krage
The Brown-headed Crow (Corvus fuscicapillus) is a species of bird in the Corvidae family. It is endemic to Indonesia.
Its natural habitats are subtropical or tropical moist lowland forests and subtropical or tropical mangrove forests. It is threatened by habitat loss.
Justification
This species has a moderately small population which may be increasingly fragmented. Declines are likely to be occurring as a result of habitat loss, although large tracts of suitable habitat currently remain secure. It is currently considered Near Threatened.
Distribution and population
Corvus fuscicapillus is endemic to eastern Indonesia, where its known distribution is highly fragmented, presumably related to some unknown habitat specialisation. There are records from the Lower Mamberamo River and Nimbokrang (near Jayapura) in northern Papua (formerly Irian Jaya), where it may prove to be more widespread, Waigeo and Gemien in the West Papuan islands, and the Aru islands1. It is widespread, but occurs in low numbers, on the Aru islands4, and quite common at Nimbokrang. Although the paucity of records suggests that this species may be rare and locally declining, it is judged to be safe in the large areas of forest without any immediate threats within its range.
Trend justification
A slow declines is suspected to be occurring, as a result of habitat loss in some parts of the species's range.
Ecology
This species primarily inhabits primary forest, but is also found in mangroves, and occasionally second growth, but rarely open habitats and never on the coast or outlying islands. It occurs in lowlands and hills up to 500 m.
Threats
Forest within its range is threatened in places by logging, a cobalt mining concession on Waigeo, and a dam proposed across the Mamberamo River, although much of the forest remains intact and relatively secure, and includes some protected areas.
ref.:
Brown-headed Crow (BirdLIfe)
Brown-headed Crow (Google)
Bro wn-headed Crow (Google Pics)
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Long-billed Crow
Corvus validus, Langnæbbet Krage
The Long-billed Crow, Corvus validus, is a crow that ranges in the Northern Moluccas (Indonesia). It has a long bill and white iris. This crow is large with glossy plumage, and is of Least Concern.
ref.:
Corvus validus (Wikipedia)
Corvus validus (Google)
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Banggai Crow
Corvus unicolor, Banggaikrage
The Banggai Crow, Corvus unicolor, is a member of the crow family from Banggai in Indonesia. It is listed as critically endangered by IUCN and was even feared extinct, but was finally rediscovered during surveys on Peleng Island by Indonesian ornithologist Mochamad Indrawan in 2007 and 2008.
It was sometimes considered a subspecies of the Slender-billed Crow, but it is actually rather distinct from this bird, resembling an entirely black Piping Crow overall. The Banggai Crow is a medium-sized crow, some 39 cm long and completely black with a dark iris and a short tail.
For more than a century, it was known from only two specimens taken from an unknown island in the Banggai Archipelago - probably in 1884/1885. Visits to the archipelago in 1991 and 1996 yielded no unequivocal records of the species, leading some to believe it was extinct. During a survey conducted between 2007 and 2008 and partially financed by the Zoological Society for the Conservation of Species and Populations (Germany), it was repeatedly seen on Peleng Island and Indonesian ornithologist Mochamad Indrawan caught and photographed two individuals. The validity of the crows on Peleng was not recognized by BirdLife International in its 2009 Red List. Confirmation of the identity based on two specimens from Peleng was made by Pamela C. Rasmussen of the American Museum of Natural History in October 2009.
The total population is estimated at approximately 500 individuals, living in mountain forest at altitudes above 500 m. The decline of the Banggai Crow is thought to be primarily due to habitat loss and degradation through agriculture and extraction.
This bird remained a complete enigma for a long time. Listed as Vulnerable in the 1994 IUCN Red List, it was changed to Endangered in 2000. In 2006, the status was considered as Possibly Extinct. Fortunately this proved to be incorrect and the status was corrected to Critically Endangered in the 2007 Red List.
ref.:
Corvus unicolor (Wikipedia)
Corvus unicolor (Google)
Corvus unicolor (Google Pics)
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Jungle Crow
Corvus levaillantii, Junglekrage
The Jungle Crow (Corvus levaillantii) is a species of bird in the Corvidae family. It is found in Bangladesh, India, Myanmar, Nepal, Sri Lanka, and Thailand.
ref.:
Jungle Crow (Wikipedia)
Jungle Crow (Google)
Jungle Crow (Google Pics)
Jungle Crow (YouTube)
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Large-biled Crow
Corvus macrorhynchos, Stornæbbet Krage
Kaldes også Thick-billed Crow og Jungle Crow
The Jungle Crow (Corvus macrorhynchos), is a widespread Asian species of crow. They are very adaptable and are able to survive on a wide range of food sources making them capable of colonizing new areas due to which they are often considered a nuisance, especially on islands. They have a large bill and due to this they are also sometimes called Large-billed Crow or Thick-billed Crow.
It has 11 subspecies, and some of these are distinctive vocally, morphologically and genetically, leading to speculations that more than one species is involved. For example:
- Corvus (m.) levaillantii - Eastern Jungle Crow
- Corvus (m.) culminatus - Indian Jungle Crow
- Corvus (m.) japonensis - Large-billed Crow
Description
The overall size (46–59 cm in length) and body proportions vary regionally. In the far northeast in Japan, the Kuriles and the Sakhalin peninsula, it is somewhat larger than the Carrion Crow, while the taxa from India in the southwest of its range is appreciably smaller than the Carrion Crow. All taxa have a relatively long bill with the upper one quite thick and arched, making it look heavy and almost Raven-like. Generally, all taxa have dark greyish plumage from the back of the head, neck, shoulders and lower body. Their wings, tail, face and throat are glossy black. The depth of the grey shading varies across its range to almost black in the Indian taxa.
Distribution and habitat
The range of this species is extensive and stretches from the northeastern Asian seaboard to Afghanistan and eastern Iran in the west, through South and Southeast Asia, to the Lesser Sundas and the Philippines in southeast. It occurs in woodland, parks and gardens, cultivated regions with a least some trees, but is a bird of more open country in the south of its range where it is not in competition with the Raven and Carrion Crow of the north.
Diet
Extremely versatile in its feeding, it will take food from the ground or in trees. They feed on a wide range of items and will attempt to feed on anything appearing edible, alive or dead, plant or animal. It is also one of the most persistent species and is quite bold, especially in urban areas. It is well known for its regular habit of killing domestic Chickens, more so than any other species of Crow. In Japan, feral crows are considered to be a pest for ripping open garbage bags and taking wire coat hangers for their nests.
Food caching behaviour has been noted in ssp. culminatus.
Breeding
The nest is a platform of twigs, usually high up on a tree with a preference for tall Conifers like Fir or Pine. There are normally 3-5 eggs laid and they are incubated for 17–19 days. The young are fledged usually by about the 35th day. In India, the various races of the Jungle Crow breed from March to May, but in the plains some of them start even in mid December. The nest is built in a fork of a tree, and is a shallow cup of sticks, sometimes neat and well made, sometimes sketchy and ragged; it is lined with grass roots, wool, rags, vegetable fibre, and similar materials. Some nests have been found to be built partly or exclusively of wire.
The normal clutch consists of four or five eggs, and rarely six or seven. The egg is a broad oval, rather pointed at the smaller end. The texture is hard and fine and there is a fair gloss. The ground-colour is any shade of blue-green, and is blotched, speckled and streaked with dull reddish-brown, pale sepia, grey and neutral tint. In size the eggs average about 1.45 by 1.05 inches. The Jungle Crow can serve as a host for the Asian Koel.
Roosting
Gregarious at roosts with many thousands at some roost sites. Large flocks may be seen at dusk arriving at major roost sites. These roosts show no apparent reduction even during the breeding season, and this is because they do not breed during their first year. During the day pairs may be involved in defending their territory but at night they may roost in large groups. They have linear dominance hierarchies that are remembered based on individual recognition.
Voice
The voice is similar to the House Crow with which it is closest to, but deeper and usually more resonant and described as the usual loud "caaa-caaa-caaa". However it makes a range of calls, some which could be described as "cau cau" and others that could be mistaken for a woodpecker drumming.
Mortality factors
There are few predators of this species. Filarial parasites have been reported from this species. Pathogenic viruses such as H5N1 has been noted to cause mortality in Japan. Large scale deaths have also been noted to be caused by Clostridium infection and enteritis.
ref.:
Jungle Crow (Large-billed Crow) (Wikipedia)
Large-billed Crow (Google)
Large-billed Crow (Google Pics)
Large-billed Crow (YouTube)
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House Crow
Corvus splendens, Huskrage
The House Crow (Corvus splendens), also known as the Colombo Crow is a common bird of the Crow family that is of Asian origin but now found in many parts of the world, where they arrived assisted by shipping. It is between the Jackdaw and the Carrion Crow in size (40 cm in length) but is relatively slimmer than either. The forehead, crown, throat and upper breast are a richly glossed black, whilst the neck and breast are a lighter grey-brown in colour. The wings, tail and legs are black. There are regional variations in the thickness of the bill and the depth of colour in areas of the plumage.
Taxonomy
In the dry parts of South Asia and Iran the subspecies C. s. zugmayeri is found and this has a very pale neck collar. The nominate race is found in India, Nepal and Bangladesh and has a grey neck collar. In southern India, the Maldives (sometimes separated as maledivicus) and Sri Lanka, the subspecies C. s. protegatus is darker grey. The darkest form however is the Myanmar form C. s. insolens and lacks the grey collar.
Distribution and habitat
It has a widespread distribution in southern Asia, being native to Nepal, Bangladesh, India, Pakistan, Sri Lanka, Maldives and Laccadive Islands, South West Thailand and coastal southern Iran. It has been introduced to East Africa around Zanzibar (around 1897) and Port Sudan, and arrived in Australia via ship but has up to now been exterminated. Recently it has made its arrival in Europe, and has been breeding in the Hook of Holland since 1998. An individual of this species has been present in Cork Harbour on the south coast of Ireland since early September 2010.
In the New World, a small population of House Crows is established in the area around St. Petersburg, Florida.
It is associated with human settlements in all of its range, from small villages to large cities. In Singapore there was a density of 190 birds/km2 in 2001 with efforts to suppress the population in planning.
Due to a human population explosion in the areas it inhabits, this species has also proportionately multiplied. Being an omnivorous scavenger has enabled it to thrive in such circumstances.
The invasive potential for the species is great all over the tropics. This species is able to make use of resources with great flexibility and appears to be associated with humans, and no populations are known to exist independently of humans.
Diet
It feeds largely on refuse around human habitations, small reptiles and other animals such as insects and other small invertebrates, eggs, nestlings, grain and fruits. Crows have also been observed swooping down from the air and snatching baby squirrels. Most food is taken from the ground, but also from trees as opportunity arises. It is a highly opportunistic bird and given its omnivorous diet, it can survive on nearly anything that is edible. These birds can be seen near marketplaces and garbage dumps, foraging for scraps.
Nesting
At least some trees in the local environment seem to be necessary for its successful breeding although they occasionally nest on telephone towers. It lays 3-6 eggs in a typical stick nest, and occasionally there are several nests in the same tree. In South Asia they are parasitized by the Asian Koel. Peak breeding in India as well as Peninsular Malaysia was from April to July. Large trees with big crowns are preferred for nesting.
Roosting
House Crows roost communally near human habitations and often over busy streets. A study in Singapore found that the preferred roost sites were in well-lit areas with a lot of human activity, close to food sources and in tall trees with dense crowns that were separated from other trees. The roost sites were often enclosed by tall buildings.
Voice
The voice is a harsh kaaa-kaaa.
Relationship to humans
It is suspected that paramyxoviruses, such as PMV 1 that causes of Newcastle disease may be spread by Corvus splendens. Outbreaks in India of Newcastle disease were often preceded by mortality in crows. They have also been found to carry Cryptococcus neoformans which can cause cryptococcosis in humans.
Crows in Tanzania curiously showed an absence of blood parasites although some species such as Trypanosoma corvi have been first described from this species.
ref.:
Corvus splendens (Wikipedia)
Corvus splendens (Google)
Corvus splendens (Google Pics)
Corvus splendens (YouTube)
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Collared Crow
Corvus pectoralis, Båndkrage
Corvus pectoralis (Google)
Corvus pectoralis (Google Pics)
Corvus pectoralis (YouTube)
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Mariana Crow
Corvus kubaryi, Marianerkrage
The Mariana Crow (Corvus kubaryi) is a species of the crow family from the north Pacific. It is an endangered species which has steadily declined in numbers since the 1960s.
Description
The Mariana Crow is a small black crow with a bluish-black gloss on its tail, and a greenish-black gloss on its back, underparts, head, and wings. In general, females are smaller than males. An adult weighs about 250 grams and is about 38 centimetres long.
The voice is a loud scream of kaaa-ah.
Distribution and ecology
The Mariana Crow inhabits second growth and mature forests, as well as coastal strand vegetations, but nests only in native limestone forest. It lives primarily in the northern end of the island of Guam, and Rota in the Northern Marianas Islands where it preferentially nests in the crowns of two canopy-emergent tree species: Yoga Tree (Elaeocarpus joga) and the fig Ficus prolixa.
Diet
Extremely versatile, the Mariana Crow is an opportunistic omnivore, feeding on insects, lizards, other birds' eggs, hermit crabs, fruits, and seeds.
Nesting
The Mariana Crow begins nesting as early as July and as late as March. The nest is a large, cupped platform of small sticks, lined with leaf fibers. Clutch size varies from 1-4 eggs, and both parents incubate the eggs, brood the chicks, and care for the juveniles even after they fledge. Parental care has been known to range from 5 to 18 months, and juveniles may take as long as 3 years before entering the adult breeding cycle.
Status and conservation
On Guam, the Mariana Crow's decline is primarily due to predation by the introduced Brown Tree Snake (Boiga irregularis). In spite of protection of nesting-sites by electrical tree barriers, the remaining birds are considered to be reproductively senescent. On Rota, many other threats endanger the crow, including homestead development, resort and golf-course construction, agricultural settlement, nest-predation from introduced rats, the Mangrove Monitor lizard (Varanus indicus), typhoons, disease, and competition with the Black Drongo (Dicrurus macrocercus). More recently, the Brown Tree Snake has also been introduced to Rota, likely leading to serious declines in the Mariana Crow population there if the snake population establishes itself. The Mariana Crow is also persecuted by residents of both islands who see it as an obstacle to development.
In 1993, a National Wildlife Refuge was established on Guam to preserve the remaining forest, and birds are being translocated from Rota. Biologically controlling the Brown Tree Snake is also being discussed.
Formerly classified as an Endangered species by the IUCN, it was suspected to be rarer than generally assumed. Following the evaluation of its status, this was found to be correct, and it is consequently uplisted to Critically Endangered status in 2008 as it is in immediate danger of extinction, numbering so few birds that it might be entirely wiped out by a single catastrophic event such as an epidemic of West Nile Virus.
ref.:
Mariana Crow (Wikipedia)
Mariana Crow (Google)
Mariana Crow (Google Pics)
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Grey Crow
Corvus tristis, Ny Guinea-råge
The Grey Crow (Corvus tristis), formerly known as the Bare-faced Crow, is about the same size (42–45 cm in length) as the Eurasian Carrion Crow (Corvus corone) but has somewhat different proportions and quite atypical feather pigmentation during the juvenile phase for a member of this genus.
The tail feathers are relatively long and graduated and the legs are relatively short. The overall colouring of the adult bird is black with randomly bleached wing and tail feathers. A large region around the eye is quite bare of feathering and shows pinkish-white skin with the eyes a bluish-white. The bill is unusual too in being very variable, bluish on upper mandible and pinkish-white on the lower in some specimens, while on others the whole bill is pinkish white with a darker tip. The forward pointing nasal bristles so often prominent in other Corvus species are very reduced also.
The juvenile bird by comparison has remarkably pale plumage being light brown to cream, the wings, tail and primaries showing blackish-brown and fawn and the head and underparts often almost white.
The species occurs all over the huge island of New Guinea and associated offshore islands in both primary and secondary forest in both lowland and hill forest up to 1350 m.
Feeding is both on the ground and in trees taking a very wide range of items. Fruit seems to be very important making up a large percentage of the intake though small animals such as frogs and aquatic insect larvae are taken from shallow water on sand or shingle beds in rivers. When foraging through the trees the birds keep loose, noisy contact with each other and usually number between 4–8 individuals.
The voice is described as a weak sounding 'ka' or a whining 'caw' with other hoarse sounding notes added when excited.
ref.:
Corvus tristis (Wikipedia)
Corvus tristis (Google)
UK Name (YouTube)
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Bougainville Crow
Corvus meeki, Salomonkrage
The Bougainville Crow (Corvus meeki) is a species of bird in the crow family Corvidae. It is found in on the island of Bougainville in Papua New Guinea and the neighbouring Shortland Islands in the Solomon Islands. Within its range it is the only species of crow.
The Bougainville Crow is a heavy crow, 41 cm long, with all black plumage and a massive black bill.
Its natural habitats are subtropical or tropical moist lowland forests and subtropical or tropical moist montane forest up to 1600 m.[2] It is a common species on Bougainville, but it might be threatened in the future by habitat loss caused by logging.
ref.:
Bougainville Crow (Wikipedia)
Bougainville Crow (Google)
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White-billed Crow
Corvus woodfordi, Lysnæbbet Krage
The White-billed crow (Corvus woodfordi) is a member of the Crow family found on the Solomon Islands.
It is a short and stocky forest bird (40-41 cm in length) with a short, squared-off tail and a relatively large head with a very distinctive deep and curved pale ivory-coloured bill with a darker tip. The dark nasal bristles, though not thick, are quite apparent against the pale coloured bill. The bird overall is very glossy black with a greenish-purple gloss to the head and purple gloss to the rest of the body. The iris is pale grey or white in the adult bird and the legs and feet are black.
The voice is described as being reminiscent of the Torresian Crow but higher in pitch and faster, giving an "ao-ao-ao" sound.
This species is confined to the central part of the Solomon Islands and can be found specifically on the islands of Choiseul, Isabel and Guadalcanal where it forages in small family groups through the trees, feeding on various insects and fruits. It is normally difficult to view as it often remains well hidden in the high forest canopy while feeding and even flying low, just over the tops of the trees when moving on.
As is the case with many forest crows, there is little information on the species' breeding habits.
ref.:
Corvus woodfordi (Wikipedia)
Corvus woodfordi (Google)
Corvus woodfordi (Google Pics)
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Piping Crow
Corvus typicus, Sulawesikrage
The Piping Crow (Corvus typicus) is a species of bird in the Corvidae family. It is endemic to Indonesia.
Its natural habitat is subtropical or tropical moist lowland forests.
ref.:
Corvus typicus (Wikipedia)
Corvus typicus (Google)
Corvus typicus (Google Pics)
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Hawaiian Crow
Corvus hawaiiensis, Hawaiikrage
The Hawaiian Crow or Alala (Corvus hawaiiensis) is a species of bird in the crow family, Corvidae. It is about the size of the Carrion Crow at 48–50 centimetres in length, but with more rounded wings and a much thicker bill. It has soft, brownish-black plumage and long, bristly throat feathers; the feet, legs and bill are black. Some Native Hawaiians consider the Hawaiian Crow an aumakua (family god).
Distribution and habitat
The Hawaiian Crow is now extinct in the wild. Before this, the species was found only in the western and southeastern parts of the island of Hawaii. It inhabited dry and mesic forests on the slopes of Mauna Loa and Hualalai at elevations of 300–2,500 metres (980–8,200 ft). Ohia lehua (Metrosideros polymorpha) and koa (Acacia koa) are important tree species in its habitat. Extensive understory cover is necessary to protect the 'alala from predation by io (Buteo solitarius), Hawaiian Hawk. Nesting sites receive 600–2,500 millimetres of annual rainfall. Fossil remains indicate that it previously was relatively abundant on all the main islands, along with four other extinct crow species. The species is known for strong flying ability and resourcefulness, and the reasons for its extinction are not fully understood. It is thought that introduced diseases, such as Toxoplasma gondii, avian malaria (Plasmodium relictum), and fowlpox, were probably a significant factor in the species' decline.
Diet
The varied diet of the omnivorous Hawaiian Crow is dominated by eggs and nestlings, invertebrates, and fruit; nectar, flowers, and carrion are minor components. Alalas will pry bark off trees and eat the insects found underneath. Ie ie (Freycinetia arborea) vines are an important fruit source, although the birds are not normally seen in wet forests, where ie ie density is highest.
Voice
The Hawaiian Crow has a call described variously as a two-toned caw and as a screech with lower tones added, similar to a cat's meow. It also makes a ca-wak sound, has a complex, burbling song, and makes a variety of other sounds as well.
Conservation status
The last two known wild individuals of this species disappeared in 2002; the species is now classified as Extinct in the Wild by the IUCN Red List. While some 78 individuals remain (as of July 2010) in two captive breeding facilities operated by the San Diego Zoo, attempts to reintroduce captive-bred birds into the wild have been hampered by predation by the Hawaiian Hawk (Buteo solitarius), which is listed as Near Threatened.
On April 16, 2009, The U.S. Fish and Wildlife Service announced a five year plan to spend more than $14 million to prevent the extinction of the Hawaiian Crow through protection of habitats and management of threats to the species.
ref.:
Hawaiian Crow (Wikipedia)
Hawaiian Crow (Google)
Hawaiian Crow (Google Pics)
Hawaiian Crow (YouTube)
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Torresian Crow
Corvus orru orru, Ny guinea-krage
The Torresian Crow (Corvus orru), also occasionally called the Australian Crow or Papuan Crow in those respective countries, is an Australasian member of the crow genus. An all black crow, it is found in the north and west of Australia and islands to the north.
Taxonomy
The Torresian Crow was described by ornithologist Charles Lucien Bonaparte in 1850, with the Australian subspecies ceciliae described by Mathews in 1912. In Central Australia southwest of Alice Springs, the Pitjantjatjara term for race ceciliae is kaanka. The term wati kaanka refers to a light-fingered man or someone who hangs around suspiciously.
Description
The Torresian Crow is about the same size (50–55 cm in length) as the Eurasian Carrion Crow but with a more robust bill and slightly longer legs. It has the typical white iris of the other Australasian Corvus species but can be distinguished from most (except the Little Crow) by the base of the head and neck feathers being snow white (revealed when blown by a strong wind). It also shuffles its wings after alighting.
Distribution and habitat
The range of the mainland Australian race C. orru ceciliae occupies the tropical north of Australia as far south as Brisbane on the east coast where the species seems to be adjusting well to a city life. Over much of this range, it is simple to distinguish from other species, as it is the only corvid found in northern Australia.
The other three races occur on various islands to the north: C. orru orru (the nominate form from Papua New Guinea and the Moluccas), C. orru insularis from New Britain and nearby islands and lastly C. orru latirostris of Tenimber and Barbar Islands.
The Australian Crow is not to be confused with the Australian Raven, which has an almost identical appearance. Despite their visual similarities, the Australian Raven and Crow (Corvus orro) have very different and unique calls.
Diet
A typical crow in that it will take just about anything. It has been seen taking stranded fish on the seashore, carrion, human food scraps, fruit and insects. Adaptable and intelligent like its North American, European, African and Asian relatives, it has learned how to kill and eat the introduced poisonous Cane Toad without ingesting the poison by flipping it onto its back and delivering a lethal blow with its powerful bill. It will also pick on skin parasites off of the Australian Banteng (a relationship that took around 150 years to develop).
Nesting
Two to four eggs in large stick nest high in a tree.
Voice
Quite different from the Australian Raven. A nasal "uk-uk-uk-uk-uk" or sometimes an "ok-ok-ok-ok".
ref.:
Corvus orru orru (Wikipedia)
Corvus orru orru (Google)
Corvus orru orru (Google Pics)
Corvus orru orru (YouTube)
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LIttle Crow
Corvus bennetti, Lille Krage
Kaldes også Bennett's Crow
The Little Crow (Corvus bennetti) is an Australian species of crow, very similar to the Torresian Crow in having white bases to the neck and head feathers (shown when ruffled in strong wind) but slightly smaller (42-48 cm in length) and with a proportionately smaller bill. It has the same white iris that distinguish the Australian species from all other Corvus except a few island species to the north of Australia, and one from Eurasia, the Jackdaw (Corvus monedula). Like the Australian Raven, this species usually has a blue ring around the pupil and sometimes one around the very outer edge of the white iris too.
Distribution and habitatIt
ranges over western and central Australia, often inhabiting very dry, near desert areas. It frequents small country towns and cultivated areas, where its flocks have reminded people of the European Rook.
Diet
Its food is mainly taken from the ground and includes insects, cereals and other seeds. It is less of a scavenger or carrion feeder than the other Australian species.
Nesting
It usually nests in small, loose colonies, building stick nests lined with mud (the only Australian species to do this.
Voice
Its voice is a "nark-nark-nark-nark". It also has a more typical crow-like "kah-kah-kah" call.
ref.:
Little Crow (Wikipedia)
Little Crow (Google)
Little Crow (Google Pics)
LIttle Crow (YouTube)
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Australian Raven
Corvus coronoides, Australsk Ravn
Kaldes også Southern Raven, Southern Crow, Wugan og Kelly.
The Australian Raven (Corvus coronoides) is the largest Australian member of the genus Corvus and one of three Australian species commonly known as ravens. It is a more slender bird than the Common Raven of the Northern Hemisphere but is otherwise similar. It has all-black plumage, beak and legs with a white iris, as do the other Corvus members in Australia and some species from the islands to the north. It is distinguished by its prominent throat hackles and grey bases of its black feathers. It is omnivorous, has adapted well to urban environments and is a common city bird in Sydney and Canberra.
Taxonomy and naming
The Australian Raven was first described by Nicholas Aylward Vigors and Thomas Horsfield in 1827; its specific epithet coronoides "crow-shaped" is derived from the Greek corone/?????? "crow" and eidos/e?d?? "shape" or "form". The two naturalists regarded the Australian Raven as very similar in appearance to the Carrion Crow (C. corone) of Europe.
Although called a raven, its closest affinities lie with the other four species of Australian corvid, which include the Torresian Crow and Little Crow as well as the Forest Raven and Little Raven. Alternate names sometimes seen include Southern Raven, Southern Crow, and Kelly. It was called wugan by the local Eora and Darug inhabitants of the Sydney basin.
Two subspecies are recognised:
- C. c. coronoides, the nominate subspecies, is found across most of eastern Australia.
- C. c. perplexus occurs from the head of the Great Australian Bight in South Australia westwards into Western Australia where its northern limits are Shark Bay and the mulga-eucalypt boundary line.
Intermediate birds are found in the Eyre Peninsula, Gawler Ranges and vicinity of Lake Eyre in South Australia.
Description
Measuring 46–53 cm in length with a 100 cm wingspan and weighing around 650 g, the adult Australian Raven is an all black bird with black feet and beak and a white iris. The plumage is glossy with a blue-purple to blue-green sheen, greenish over the ear coverts, depending on light. The underparts are not glossy. Its throat feathers (hackles) are longer than those of other species. It can be distinguished from the two species of crow occurring in Australia by the grey base of the feathers, which is white in the latter species. Juveniles resemble adults, but have dark eyes, shorter throat hackles, and sometimes have a pink fleshy gape.
The territorial call of the Australian Raven is a slow, high ah-ah-aaaah with the last note drawn out. It will use this call to communicate with other Australian Ravens in the area. The five Australian species are very difficult to tell apart, with the call being the easiest way to do so.
Distribution and habitat
The Australian Raven is common throughout south-eastern Australia, and southern Western Australia (the populations being connected by a narrow strip across the Nullarbor Plain), but it is not found in the far north. It is found on some offshore islands such as Rottnest Island. and Kangaroo Island. The Australian Raven can be found in a wide range of natural and modified habitats. It requires available water and trees (or buildings) to roost in or perch on. Preferred habitats include eucalypt-dominated sclerophyll forest, and farmland adjacent to trees. It is also found in heath and mangroves. In areas where it occurs with the Little Raven, it is restricted to more forested areas while the latter species prefers more open areas.
The Australian Raven has adapted very well to human habitation in some cities and is a common bird in Canberra and Sydney; in Melbourne it is replaced as the common corvid by the Little Raven.
Behaviour
In rural areas a single breeding pair and their brood will occupy about a square kilometre territory, whilst in urban areas over ten times as many ravens can search for food in the same square kilometre.
Diet
Food consists of carrion, insects, seeds, fruit, small reptiles, nestlings and eggs. The preference ratio is 34% carrion, 42% invertebrates and 24% plant material. Food is taken mainly from the ground but will occasionally feed in trees. Ravens have adapted well to eating rubbish and scraps in urban areas, such as school playgrounds. In one isolated study they were observed feeding on nectar from eucalypt flowers.
Reproduction
Breeding season is from July to September. Ravens always nest in tall trees, never near to the ground as some species do. Nests are generally large and untidy, consisting of a bowl or platform of sticks lined with grasses, barks, and feathers. A clutch can comprise 3–6 eggs, though usually 4 or 5 are laid. Measuring 45x30 mm, eggs are pale green or bluish-green splotched with darker olive, brown and blackish markings. Incubation of the eggs is done solely by the female over roughly 20 days. Only one brood is raised per year. Fledged by 45 days and staying with parents for about four months after that.
Relationship with humans
The Australian Raven is frequently blamed for the loss of young lambs or kids. Scientific observation in the country's southeast showed that the killing of healthy lambs was rare but that sick animals were predisposed to being attacked.
ref.:
Australian Raven (Wikipedia)
Australian Raven (Google)
Australian Raven (Google Pics)
Australian Raven (YouTube)
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Little Raven
Corvus mellori, Dværgravn
The Little Raven (Corvus mellori) is a species of the crow and raven family Corvidae, that is endemic to Australia. It has all-black plumage, beak and legs with a white iris, as do the other Corvus members in Australia and some species from the islands to the north.
Taxonomy
Although the Little Raven was first named by Mathews in 1912, it was only in 1967 that there was consensus to separate it from the Australian Raven (C. coronoides) as a distinct species.
Description
Some of the differences, between the two species, are that the Little raven: on average a little smaller than the Australian Raven (48–50 cm in length), though sizes do overlap between both species; the beak is slightly smaller and more curved, calls are shorter and the throat bulges out less while calling. This bird is a somewhat more sociable species by comparison, often forming large flocks that roam freely over wide areas in search of food. The range of the Little raven does overlap the range of the Australian Raven, but the Australian Raven's range extends further.
Distribution and habitat
The Little Raven ranges over southeastern Australia from southern South Australia, Victoria and New South Wales. Also in Kangaroo Island (S.A.) and King Island (Bass Strait). Living within scrub, agricultural areas, grazing pasture, woodlands to treeless plains, coasts, and suburbs. Little Ravens are absent from west Gippsland, where the land is dominated by Forest Ravens
Diet
Little Ravens tend to eat rather more vegetable matter than C. coronoides and to feed mainly on the ground, but is probably omnivorous to a similar extent to other Corvus species when opportunity arises.
Nesting
Little Ravens often nest in a loose colony of up to fifteen pairs, with nests few meters apart. They have often been recorded as having several nests within the nesting territory of a single Australian Raven which, presumably due to different food preferences, does not seem to consider them a threat to its own food resources.
The nest is a thin cup of sticks with a layer of bark, grass and wool to create a thick mat. Nests are commonly low to the ground (under 10 meters), often in a forked branch in the outer canopy of a tree. Juveniles have brown colored eyes until their 3rd year, their eye color changes to white.
Voice
Its call is a harsh, guttural "kar-kar-kar-kar" or "ark-ark-ark-ark". They also do a quick upward flick of both wings with each note.
ref.:
LIttle Raven (Wikipedia)
Little Raven (Google)
Little Raven (Google Pics)
Little Raven (YouTube)
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Forest Raven
Corvus tasmanicus, Tasmansk Ravn
Corvus tasmanicus boreus, Skovravn
The Forest Raven (Corvus tasmanicus) is a large species of the crow genus native to south-eastern Australia and Tasmania.
Description
The Forest Raven is 50–52 cm in length with glossy black plumage and a white iris. It has a proportionately larger bill and shorter tail than the other mainland corvid species and is the sole representative of the genus Corvus in Tasmania. The call is a deep "korr-korr-korr-korr" with a similarly drawn out last note to the Australian Raven.
Subspecies
An outlying population exists in a small area in the tablelands of north-eastern New South Wales. The suggestion that this form be given specific rank and be known as the Relict Raven (Corvus boreus) appears not to have gathered favour, and the Relict Raven remains classified as a subspecies, C. tasmanicus boreus.
A scientific study of the Forest Raven (C. tasmanicus) and the Little Raven (C. mellori) is being undertaken by the Victorian Ornithological Research Group in Victoria.
Distribution and habitat
The Forest Raven inhabits a wide range of habitat within Tasmania such as woods, open interrupted forest, mountains, coastal areas, farmland and town and city fringes. It is also found in southern Victoria from Gippsland west through Wilson's Promontory and the Otway Ranges. Further west, it occurs patchily in south-east South Australia.
In its present stronghold — the state of Tasmania — the Forest Raven is one of only four native birds that have no legal protection outside national parks and other reserves. The other three unprotected species are the Tasmanian Native-hen (a Tasmanian endemic), the Great Cormorant and the Little Pied Cormorant. All other native Tasmanian birds are listed as protected under the state's Nature Conservation Act 2002.
Diet
A typical omnivore taking a very wide range of foods such as insects, carrion, fruit, grain and earthworms. It has been known to kill and eat birds as large as the Silver Gull (Larus novaehollandiae) using some degree of cunning by pretending to forage near enough to get close for the kill.
Nesting
A stick nest, very similar to the mainland Australian Raven and like it, built always high up in tall trees.
ref.:
Forest Raven (Wikipedia)
Corvus tasmanicus (Google)
Corvus tasmanicus (Google Pics)
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