Crows of the World

 

This is a survey of crows and ravens from all over the world. Bird names are stated in English, Latin and Danish (being a dane myself). Should you find any error or misleading information, don't hesitate to contact me. Please mail:

Sincerely
Kurt Starlit
aka Cykelkurt

 

Crows of the World, part 2

 

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Common Raven
Also called Northern Raven
Corvus corax corax, da. Alm. Ravn

large pic.

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.

• 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.

Evolutionary history
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."
—Candace Savage

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.

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)

Ravens (photos by Paul Lantz)

Corvus corax (Google Pics)

The voice (Corvus corax)

 

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Pied Raven
Corvus corax varius, da. 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 hvittravnur ("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.

Diðrikur 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 Listasklin museum of Faroe art in Thorshavn.

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 Nollsoy, 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)

Hvidbroget Ravn

 

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Carrion Crow
Corvus corone, da. Sortkrage

Carrion Crow (Corvus corone)

The Carrion Crow (Corvus corone) is a member of the passerine order of birds and the crow family which is native to western Europe and eastern Asia.

Taxonomy
The Carrion Crow 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 corone. The binomial name is derived from the Latin Corvus, "Raven", and Greek corone/??????, "crow".

As well as the subspecies of the Hooded Crow being split off as a separate species, there is some discussion whether the Eastern Carrion Crow (C. c. orientalis) is distinct enough to warrant specific status; the two taxa are well separated, and it has been proposed they could have evolved independently in the wetter, maritime regions at the opposite ends of the Eurasian landmass.

Description
The plumage of Carrion Crow is black with a green or purple sheen, much greener than the gloss of the Rook. The bill, legs and feet are also black. It can be distinguished from the Common Raven by its size (48–52 cm or 18 to 21 inches in length) and from the Hooded Crow by its black plumage, but there is frequent confusion between it and the Rook. The beak of the Crow is stouter and in consequence looks shorter, and whereas in the adult Rook the nostrils are bare, those of the Crow are covered at all ages with bristle-like feathers.

Distribution and habitat
This species breeds in western and central Europe, with an allied form or race C. c. orientalis (50–56 cm or 19 to 22 inches in length) occurring in eastern Asia. The separation of these two populations is now believed to have taken place during the last ice age, with the closely allied Hooded Crow (now given species status) filling the gap between. Fertile hybrids occur along the boundary between these two forms indicating their close genetic relationship. This is an example of the parapatric speciation model described by Ernst Mayr. The range of this hybrid of these two species appears to be moving to the northwest.

Behaviour
The Rook is generally gregarious and the Crow solitary, but Rooks occasionally nest in isolated trees, and Crows may feed with Rooks; moreover, Crows are often sociable in winter roosts. The most distinctive feature is the voice. The rook has a high-pitched kaaa, but the Crow's guttural, slightly vibrant, deeper croaked kraa is distinct from any note of the rook.

The Carrion Crow is noisy, perching on the top of a tree and calling three or four times in quick succession, with a slight pause between each series of croaks. The wing-beats are slower, more deliberate than those of the Rook.

Like all Corvids, Carrion Crows are highly intelligent, and are among the most intelligent of all animals

Diet
Though an eater of carrion of all kinds, the Carrion Crow will eat insects, worms, grain, small mammals, and scraps and will also steal eggs. Crows are scavengers by nature, which is why they tend to frequent sites inhabited by humans in order to feed on their household waste. Crows will also harass birds of prey or even foxes for their kills. Crows actively hunt and occasionally co-operate with other crows to make kills.

Crows have become highly skilled at adapting to urban environments. In a Japanese city, carrion crows have discovered how to eat nuts that they usually find too hard to tackle. One method is to drop the nuts from height on to a hard road in the hope of cracking it. Some nuts are particularly tough, so the crows drop the nuts among the traffic. That leaves the problem of eating the bits without getting run over, so some birds wait by pedestrian crossings and collect the cracked nuts when the lights turn red.

Nesting
The bulky stick nest is usually placed in a tall tree, but cliff ledges, old buildings and pylons may be used as well. Nests are also occasionally placed on or near the ground. The nest resembles that of the Common Raven, but is less bulky. The 3 to 4 brown-speckled blue or greenish eggs are incubated for 18–20 days by the female alone, who is fed by the male. The young fledge after 29–30 days.

It is not uncommon for an offspring from the previous years to stay around and help rear the new hatchlings. Instead of seeking out a mate, it looks for food and assists the parents in feeding the young.

ref.:
Carrion Crow (Wikipedia)

Carrion Crow (Google)

Carrion Crow (Google Pics)

Corvus corone (YouTube)

The voice (Corvus corone)

 

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Hooded Crow
Corvus cornix, Gråkrage

Hooded Crow (Corvus cornix)
Photo: Jan Jindra

The Hooded Crow (Corvus cornix) (sometimes called Hoodiecrow) is a Eurasian bird species in the crow genus. Widely distributed, it is also known locally as Scotch Crow, Danish Crow, and Corbie or Grey Crow in Ireland; Grey Crow is also what its Welsh name, Brân Lwyd, translates as. Found across Northern, Eastern and Southeastern Europe, as well as parts of the Middle East, it is an ashy grey bird with black head, throat, wings, tail and thigh feathers, as well as a black bill, eyes and feet. Like other corvids it is an omnivorous and opportunistic forager and feeder.

It is so similar in morphology and habits to the Carrion Crow (Corvus corone) that for many years they were considered by most authorities to be merely geographical races of one species. The fact that hybridization was observed where their ranges overlapped added weight to this view. However, since 2002, the Hooded Crow has been elevated to full species status after closer observation; the hybridisation was less than expected and hybrids had decreased vigour. Within the Hooded Crow species, four subspecies are recognized, with one, the Mesopotamian Crow, possibly distinct enough to warrant species status itself.

Taxonomy
The Hooded Crow was one of the many species originally described by Linnaeus in his 18th-century work Systema Naturae and it once again bears its original name of Corvus cornix.[1] The binomial name is derived from the Latin words Corvus, "Raven",[2] and cornix, "crow".[3] It was subsequently considered a subspecies of the Carrion Crow for many years,[4] and hence known as Corvus corone cornix, due to similarities in structure and habits. Since 2002, it has been re-elevated to full species status[verification needed].

It is locally known as a Hoodie in Northern Ireland.

Subspecies
Four subspecies of the Hooded Crow are now recognised; previously all were considered subspecies of Corvus corone. A fifth, Corvus cornix sardonius (Trischitta, 1939) has been listed though it has been alternately partitioned between C. c. sharpii (most populations), C. c. cornix (Corsican population) and the Middle Eastern C. c. pallescens. • C. c. cornix, the nominate race, occurs in the British Isles (principally Scotland and Ireland) and Europe, south to Corsica.
• C. c. pallescens (Madarász, 1904) is found in Turkey and Egypt, and is a paler form as its name suggests.
• C. c. sharpii (Oates, 1889) is named for English zoologist Richard Bowdler Sharpe. This is a paler grey form found from western Siberia through to the Caucasus region and Iran.
• C. c. capellanus (P.L. Sclater, 1877) is known as the Mesopotamian Crow or Iraqi Pied Crow. This distinctive form occurs in Iraq and southwestern Iran. It has very pale grey plumage which looks almost white from a distance.[7] It is possibly distinct enough to be considered a separate species.

Description
Except for the head, throat, wings, tail and thigh feathers, which are black and mostly glossy, the plumage is ash-grey, the dark shafts giving it a streaky appearance. The bill and legs are black; the iris dark brown. There is only one moult, in autumn, as in other crow species. The male is the larger bird, otherwise the sexes are alike. The flight is slow and heavy and usually straight. The length varies from 48 to 52 cm (19 to 20 in). When first hatched the young are much blacker than the parents. Juveniles have duller plumage with bluish or greyish eyes and initially a red mouth. Wingspan is 98 cm (39 in) and weight is on average 510 grammes.

The Hooded Crow, with its contrasted greys and blacks, cannot be confused with either the Carrion Crow or Rook, but the kraa (help·info) call notes of the two are almost indistinguishable.

Distribution and habitat
The Hooded Crow breeds in northern and eastern Europe, and closely allied forms inhabit southern Europe and western Asia. Where its range overlaps with Carrion Crow, as in northern Britain, Germany, Denmark, northern Italy and Siberia, their hybrids are fertile. However, the hybrids are less well- adapted than pure-bred birds, and this is one of the reasons that this species was split from the Carrion Crow.[11] There are some areas, such as Iran and central Russia, where little or no interbreeding occurs.

In the British Isles, the Hooded Crow breeds regularly in Scotland, the Isle of Man, and in the Scottish Islands. It also breeds widely in Ireland. In autumn some migratory birds arrive on the east coast of Britain. In the past, this was a more common visitor, and in Hertfordshire was known as the Royston Crow after the town of Royston. The 150-year old local newspaper is still titled Royston Crow, and depicts the bird’s head on its masthead.

Diet
The Hooded Crow is omnivorous, with a diet similar to that of the Carrion Crow, and is a constant scavenger. It drops molluscs and crabs to break them after the manner of the Carrion Crow, and an old Scottish name for empty sea urchin shells was "crow's cups".[12] On coastal cliffs the eggs of gulls, cormorants and other birds are stolen when their owners are absent, and it will enter the burrow of the Puffin to steal eggs. It will also feed on small mammals, scraps, smaller birds and carrion.

Nesting
Nesting occurs later in colder regions: mid-May to mid-June in northwest Russia, Shetland and the Faroe Islands, and late February in the Persian Gulf region. In warmer parts of the British Isles, the clutch is laid in April. The bulky stick nest is normally placed in a tall tree, but cliff ledges, old buildings and pylons may be used. Nests are occasionally placed on or near the ground. The nest resembles that of the Carrion Crow, but on the coast seaweed is often interwoven in the structure, and animal bones and wire are also frequently incorporated. The four to six brown-speckled blue eggs are 4.3 x 3.0 centimetres (1.7 x 1.2 in) in size and weigh 19.8 grammes (0.71 oz), of which 6% is shell. The altricial young are incubated for 17–19 days by the female alone, who is fed by the male. They fledge after 32 to 36 days. Incubating females have been reported to obtain most of their own food and later that for their young.

The typical lifespan is unknown, but that of the Carrion Crow is four years.[16] The maximum recorded age for a Hooded Crow is 16 years, and 9 months old.

This species is a secondary host of the parasitic Great Spotted Cuckoo, the European Magpie being the preferred host. However, in areas where the latter species is absent, such as Israel and Egypt, the Hooded Crow becomes the normal corvid host.

This species, like its relative, is seen regularly killed by farmers and on grouse estates. In County Cork, Ireland the county's gun clubs shot over 23,000 Hooded Crows in two years in the early 1980s.

Status
The IUCN Red List does not distinguish the Hooded Crow from the Carrion Crow, but the two species together have an extensive range, estimated at 10 million square kilometres (3.8 million square miles), and a large population, including an estimated 14 to 34 million individuals in Europe alone. They are not believed to approach the thresholds for the population decline criterion of the IUCN Red List (i.e., declining more than 30% in ten years or three generations), and are therefore evaluated as Least Concern.[9][18] The Carrion Crow/Hooded Crow hybrid zone is slowly spreading northwest, but the Hooded Crow has of the order of three million territories in just Europe (excluding Russia).

Cultural Significance
In Celtic folklore, the bird appears on the shoulder of the dying Cú Chulainn,[19] and could also be a manifestation of the Morrígan, the wife of Tethra, or the Cailleach.[20] This idea has persisted, and the Hooded Crow is associated with fairies in the Scottish highlands and Ireland; in the 18th century, Scottish shepherds would make offerings to them to keep them from attacking sheep.[21] In Faroese folklore, a maiden would go out on Candlemas morn and throw a stone, then a bone, then a clump of turf at a Hooded Crow – if it flew over the sea, her husband would be a foreigner; if it landed on a farm or house, she would marry a man from there; but if it stayed put, she would remain unmarried.

The Hooded Crow is featured on the crest of the North Hertfordshire District Council. It is also one of the 37 Norwegian birds depicted in the Bird Room of the Royal Palace in Oslo. Jethro Tull mentions the Hooded Crow on the song "Jack Frost and the Hooded Crow" as a bonus track on the digitally remastered version of Broadsword and the Beast and on their The Christmas Album.

ref.:
Hooded Crow (Wikipedia)

Hooded Crow (Google)

Hooded Crow (Google Pics)

Corvis cornix (YouTube)

The voice (Corvus cornix)

 

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Rook
Corvus frugilegus, da. Råge

Rook (Corvus frugilegus)

The Rook (Corvus frugilegus) is a member of the Corvidae family in the passerine order of birds. Named by Carl Linnaeus in 1758,[2] the species name frugilegus is Latin for "food-gathering".

This species is similar in size (45–47 cm in length) to or slightly smaller than the Carrion Crow with black feathers often showing a blue or bluish-purple sheen in bright sunlight. The feathers on the head, neck and shoulders are particularly dense and silky. The legs and feet are generally black and the bill grey-black.

Rooks are distinguished from similar members of the crow family by the bare grey-white skin around the base of the adult's bill in front of the eyes. The feathering around the legs also looks shaggier and laxer than the congeneric Carrion Crow. The juvenile is superficially more similar to the Crow because it lacks the bare patch at the base of the bill, but it has a thinner bill and loses the facial feathers after about six months. Collective nouns for rooks include building, parliament, clamour and storytelling. Their nesting patterns gave rise to the term rookery.

Distribution and habitat
Though resident in Great Britain, Ireland and much of north and central Europe, vagrant to Iceland and northern Scandinavia, it also occurs as an eastern race in Asia where it differs in being very slightly smaller and more efficient on average, and having a somewhat more fully feathered face. In the north of its range the species has a tendency to move south during autumn though more southern populations are apt to range sporadically also. The species has been introduced to New Zealand, with several hundred birds being released there from 1862 to 1874, though today their range is very localised. There the species is an agricultural pest and it is being eradicated.

Diet
Food is predominantly earthworms and insect larvae, which the bird finds by probing the ground with its strong bill. It also eats cultivated cereal grain, smaller amounts of fruit, small mammals, acorns, small birds, their eggs and young and carrion. In urban sites, human food scraps are taken from rubbish dumps and streets, usually in the early hours when it is relatively quiet. It has also been seen along the seashore, feeding on insects, crustaceans and suitable food flotsam.

Nesting
The distribution of rook colony sizes in Normandy.[6] Most colonies are small, a few are large (smoothed). Nesting in a rookery is always colonial, usually in the very tops of the trees. Branches and twigs are broken off trees (very rarely picked up off the ground), though as many are likely to be stolen from nearby nests as are collected from trees. Eggs are usually 3–5 in number, can appear by the end of February or early March and are incubated for 16–18 days. Both adults feed the young, which are fledged by the 32nd or 33rd day.

In autumn, the young birds of the summer collect into large flocks together with unpaired birds of previous seasons, often in company with Jackdaws. It is during the autumn that spectacular aerial displays can be seen by adult birds that seem to delight in the autumn gales.

Voice
The call is usually described as "kaah" – it is similar to that of the Carrion Crow, but usually rather flatter in tone. It is given both in flight and while perched, when the bird fans its tail and bows on each caw. Calls in flight are usually given singly, in contrast to the Carrion Crow's which are in groups of three or four. Solitary birds often "sing" apparently to themselves, uttering strange clicks, wheezes and almost human-like notes.

Intelligence
In captivity, when confronted with problems, rooks have been documented as one of several species of birds capable of using tools to obtain a goal. Rooks learned that if they push a stone off a ledge into a tube, they will get food. The rooks then discovered they could go get a stone and carry it to the tube if no stone was there already. They also used sticks, wire and figured out how to bend a wire into a hook to reach an item. Rooks are as clever at making and using simple tools with their beaks as chimpanzees are with their hands.

In an experiment, a rook was placed near a tube of water, with a worm floating on top of the water, and some rocks next to the tube. The water level was too low for the rook to reach the worm. The rook placed rocks into the tube until the water level was high enough for the rook to reach the worm.

Sociability
"A lady wrote to the correspondence columns of a newspaper to recount an interesting experience. The trees in her garden provided the nesting site for a large colony of rooks. One day she observed a pair of the birds starting to build their nest at some distance from the main colony, but this independence could not be tolerated by the rest of the colony (rooks are strongly social and gregarious) and they demolished this attempt at a break- away. The couple did not give up, but persisted in a second attempt; this suffered a like fate, as did their third attempt at diversity. The day after their third effort had failed, the lady was awoken by unusual sounds from the birds. She got up and went to the window, from where she saw the rooks ranged in a circle on the grass, and in the center of the circle was an isolated pair. After a period of agitated excitement the mob attacked the errant pair and killed them."

ref.:
Rook (Wikipedia)

Rook (Corvus frugilegus) (Google)

Rook (Corvus frugilegus) (Google Pics)

Corvus frugilegus (YouTube)

Rook (Corvus frugilegus)

 

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Jackdaw
Corvus monedula, da. Allike

Western Jackdaw
The Western Jackdaw (Corvus monedula), sometimes known as the Eurasian Jackdaw, European Jackdaw or simply Jackdaw, is a passerine bird in the crow family. Found across Europe, western Asia and North Africa, it is mostly resident, although northern and eastern populations migrate south in winter. Four subspecies are recognised, which mainly differ in the colouration of the plumage on the head and nape. Linnaeus first described it formally, giving it the name Corvus monedula. Later analysis of its DNA shows that, with its closest relative the Daurian Jackdaw, it is an early offshoot from the genus Corvus, and possibly distinct enough to warrant reclassification in a separate genus, Coloeus. The common name derives from the word "jack", meaning "small", and "daw", the native English name for the bird.

Measuring 34–39 centimetres (13–15 in) in length, the Western Jackdaw is a black-plumaged bird with a grey nape and distinctive pale-grey irises. It is gregarious and vocal, living in small groups with a complex social structure in farmland, open woodland, on coastal cliffs, and in urban settings. An omnivorous and opportunistic feeder, it eats a wide variety of plant material and invertebrates, as well as food waste from urban areas. Western Jackdaws are monogamous and build simple nests of sticks in cavities in trees, cliffs, or buildings. About five pale blue or blue-green eggs with brown speckles are laid and incubated by the female. The young then fledge in four to five weeks.

Etymology
The Western Jackdaw was one of the many species originally described by Linnaeus in his 18th century work Systema Naturae. Owing to its supposed fondness for picking up coins, Linnaeus gave it the binomial name Corvus monedula, choosing the specific name monedula, which is derived from moneta, the Latin stem of the word "money". The genus Coloeus, from the Ancient Greek ??????? (koloios) for jackdaw, was created by Peter Pallas in 1766, though most subsequent works have retained the two jackdaw species in Corvus.

The original Old English word ceo (pronounced with initial ch) gave modern English "chough"; Chaucer sometimes used this word to refer to the Western Jackdaw, as did Shakespeare in Hamlet although there has been debate about which species he was referring to. This onomatopoeic name, based on the Western Jackdaw's call, now refers to corvids of the genus Pyrrhocorax; the Red-billed Chough (Pyrrhocorax pyrrhocorax), formerly particularly common in Cornwall, became known initially as the "Cornish Chough" and then just the "Chough", the name transferring from one species to the other.

The common name jackdaw first appeared in the 16th century, and is thought to be a compound of the forename Jack, used in animal names to signify a small form (e.g. Jack Snipe), and the native English word daw. Formerly, Western Jackdaws were simply called "daws". The metallic chyak call may be the origin of the jack part of the common name, but this is not supported by the Oxford English Dictionary. Daw, first used for the bird in the 15th century, is held by the Oxford English Dictionary to be derived from the postulated Old English dawe, citing the cognates in Old High German taha, Middle High German tahe or tachele, and modern German Dahle or Dohle, and dialectal Tach, Dähi, Däche and Dacha.

Names in English dialects are numerous. Scottish and north English dialects have included ka or kae since the 14th century. The Midlands form of this word was co or coo. Caddow is potentially a compound of ka and dow, a variant of daw. Other dialectal or obsolete names include caddesse, cawdaw, caddy, chauk, college-bird, jackerdaw, jacko, ka-wattie, chimney-sweep bird (from their nesting propensities), and sea-crow (from the frequency with which they are found on coasts). It was also frequently known quasi-nominally as Jack.

An archaic collective noun for a group of jackdaws is a "clattering". Another name for a flock is a "train".

Taxonomy
A study in 2000 found that the genetic distance between jackdaws and the other members of Corvus was greater than that within the rest of the genus. This led Pamela Rasmussen to reinstate the genus name Coloeus in her Birds of South Asia (2005), a treatment also used in a 1982 systematic list in German by Hans Edmund Wolters. A study of corvid phylogeny undertaken in 2007 compared DNA sequences in the mitochondrial control region of several corvids. It found that the Western Jackdaw, and the closely related Daurian Jackdaw (C. dauuricus) of eastern Russia and China, were basal to the core Corvus clade. The names Coloeus monedula and Coloeus dauuricus have since been adopted by the International Ornithological Congress in their official list. The two species of jackdaw have been reported to hybridise in the Altai Mountains, southern Siberia, and Mongolia. Analysis of the mitochondrial DNA of specimens of the two species from their core ranges show them to be genetically distinct.

Subspecies
There are four recognised subspecies of the Western Jackdaw. All European subspecies intergrade where their populations meet. C. m. monedula intergrades into C. m. soemmerringii in a transition zone running from Finland south across the Baltic and eastern Poland to Romania and Croatia.

• C. m. monedula (Linnaeus, 1758), the nominate subspecies, is found in eastern Europe. Its range extends across Scandinavia, from southern Finland south to Esbjerg and Haderslev in Denmark, through eastern Germany and Poland, and south across eastern central Europe to the Carpathian Mountains and north-western Romania, Vojvodina in northern Serbia, and Slovenia. It breeds in south-eastern Norway, southern Sweden, and northern and eastern Denmark, with occasional wintering in England and France. It has been recorded as a rare vagrant to Spain. It has a pale nape and sides of the neck, a dark throat, and a light grey partial collar of variable extent.

• C. m. spermologus (Vieillot, 1817) occurs in western and central Europe from the British Isles, Netherlands and the Rhineland in the north, through western Switzerland into Italy in the south-east, and the Iberian peninsula and Morocco in the south. It winters in the Canary Islands and Corsica. The name "spermologus" comes from the Greek spe?µ??????, a picker up of seeds. It is darker in colour than the other subspecies and lacks the whitish border at the base of the grey nape.

• C. m. soemmerringii (Fischer, 1811) is found in north-eastern Europe and north and central Asia, from the former Soviet Union to Lake Baikal and north-west Mongolia, and south to Turkey, Israel and the eastern Himalayas. Its south-western limits are Serbia and southern Romania.[26] It winters in Iran and northern India (Kashmir). Johann Fischer von Waldheim described this taxon as Corvus soemmerringii in 1811, noting its differences from populations in western Europe. Its species name was given in honour of the German anatomist, Samuel Thomas von Sömmerring. It is distinguished by the nape and the sides of the neck being paler, creating a contrasting black crown and lighter grey part collar.

• C. m. cirtensis (Rothschild and Hartert, 1912) is found in Morocco and Algeria in north-western Africa and was formerly found in Tunisia. The name "cirtensis" refers to the ancient city of Cirta in Numidia. The plumage is duller and more uniformly dark grey than the other subspecies, with the paler nape less distinct.

Description
Measuring 34–39 centimetres (13–15 in) in length, the Western Jackdaw is the second smallest member of the genus Corvus.[31] Most of the plumage is a shiny black, with a purple (in subspecies monedula and spermologus) or blue (in subspecies cirtensis and soemmerringii) sheen on the crown,[32] forehead, and secondaries, and a green-blue sheen on the throat, primaries, and tail. The cheeks, nape and neck are light grey to greyish-silver, and the underparts are slate-grey. The legs are black, as is the short stout bill,[31] the length of which is about 75% of the length of the rest of the head.[32] There are rictal bristles covering around 40% of the upper mandible and 25% of the lower mandible.[32] The irises of adults are greyish or silvery white while those of juveniles are light blue, becoming brownish before whitening at around one year of age.[31] The sexes look alike,[12][33] though the head and neck plumage of male birds fades more with age and wear, particularly just before moulting.[34] Western Jackdaws undergo a complete moult from June to September in the western parts of their range, and a month later in the east.[26] The purplish sheen of the cap is most prominent just after moulting. [34]

Immature birds have duller and less demarcated plumage. The head is a sooty black, sometimes with a faint greenish sheen and brown feather bases visible; the back and side of the neck are dark grey and the underparts greyish or sooty black. The tail has narrower feathers and a greenish sheen.

There is very little geographic variation in size. The main differences are the presence or absence of a whitish partial collar at the base of the nape, the variations in the shade of the nape and the tone of the underparts. Populations in central Asia have slightly larger wings and western populations have a slightly heavier bill. Body colour becomes darker further north, in mountain regions and humid climates, and paler elsewhere. However, individual variation, particularly in juveniles and also during the months before moulting, can often be greater than geographic differences.

A skilled flyer, the Western Jackdaw can manoeuvre tightly as well as tumble and glide. It has characteristic jerky wing beats when flying, though these are not evident when birds are migrating. Wind tunnel experiments show that the preferred gliding speed is between 6 and 11 metres (20 and 36 ft) per second and that the wingspan decreases as the bird flies faster.[36] On the ground, Western Jackdaws have an upright posture and strut briskly, their short legs giving them a rapid gait. They feed with their heads held down or horizontally.

Within its range, the Western Jackdaw is unmistakable; its short bill and grey nape are distinguishing features. From a distance, it can be confused with a Rook (Corvus frugilegus), or when in flight, with a pigeon or chough. Flying Western Jackdaws are distinguishable from other corvids by their smaller size, faster and deeper wingbeats and proportionately narrower and less fingered wing tips. They also have shorter, thicker necks, much shorter bills and frequently fly in tighter flocks. They can be distinguished from choughs by their uniformly grey underwings and their black beaks and legs. The Western Jackdaw is very similar in morphology, behaviour, and calls to the Daurian Jackdaw, with which its range overlaps in western Asia. Adults are readily distinguished, since the Daurian has a pied plumage, but immature birds are much more similar, both species having dark plumage and dark eyes. The Daurian tends to be darker, with a less contrasting nape than the Western.

Voice Western Jackdaws are voluble birds. The main call, frequently given in flight, is a metallic and squeaky chyak-chyak or kak-kak. This is a contact or greeting call. A feeding call made by adults to call young, or males when offering food to their mates, has been transcribed as kiaw or kyow. Females in return give a more drawn out version when begging for food from males, written as kyaay, tchaayk or giaaaa. Perched birds often chatter together, and before settling for the night, large roosting flocks make a cackling noise. Western Jackdaws also have a hoarse, drawn-out alarm call, arrrrr or kaaaarr, used when warning of predators or when mobbing them. Nestlings begin making a soft cheep at about a week of age. As they grow, their voice becomes louder until their call is a penetrating screech around day 18. After this, the voice deepens and softens. From day 25, the young cease calling and become silent if they hear an unfamiliar noise.

Distribution and habitat
The Western Jackdaw is found from north-west Africa through all of Europe, except for the extreme north, and eastwards through central Asia to the eastern Himalayas and Lake Baikal. To the east, it occurs throughout Turkey, the Caucasus, Iran, Iraq, Afghanistan, Pakistan, and north-west India. However, it is regionally extinct in Malta and Tunisia. The range is vast, with an estimated global extent of between 1 million and 10 million square kilometres (4 hundred thousand to 4 million square miles). It has a large global population, with an estimated 15.6 to 45 million individuals in Europe alone. Censuses of bird populations in marginal uplands in Britain show that Western Jackdaws greatly increased in numbers between the 1970s and 2010, although this increase may be related to recovery from previous periods when they were regarded as pests. The UK population was estimated at 2.5 million individuals in 1998, up from 780,000 in 1970.

Most populations are resident, but the northern and eastern populations are more migratory,[25] relocating to wintering areas between September and November and returning between February and early May.[45] Their range expands northwards into Russia to Siberia during summer, and retracts in winter.[12] They are vagrants to the Faroe Islands, particularly in the winter and spring, and occasionally to Iceland.[35] Elsewhere, Western Jackdaws congregate over winter in the Ural Valley in north-western Kazakhstan, the north Caspian, and the Tian Shan region of western China. They are winter visitors to the Quetta Valley in western Pakistan,[45] and are winter vagrants to Lebanon, where they were first recorded in 1962.[46] In Syria, they are winter vagrants and rare residents with some confirmed breeding taking place.[47] The soemmerringii subspecies occurs in south-central Siberia and extreme north-west China and is accidental to Hokkaido, Japan.[48] A small number of Western Jackdaws reached the north-east of North America in the 1980s and have been found from Atlantic Canada to Pennsylvania.[49] They have also occurred as vagrants in Gibraltar, Mauritania, and Saint Pierre and Miquelon,[1] and one is reported to have been seen in Egypt.[24]

Western Jackdaws inhabit wooded steppes, pastures, cultivated land, coastal cliffs, and towns. They thrive when forested areas are cleared and converted to fields and open areas.[24] Habitats with a mix of large trees, buildings, and open ground are preferred; open fields are left to the Rook, and more wooded areas to the Eurasian Jay (Garrulus glandarius).[35] Along with other corvids such as the Rook, Common Raven (Corvus corax), and Hooded Crow (C. cornix), some Western Jackdaws spend the winter in urban parks; populations measured in three urban parks in Warsaw show increases from October to December, possibly due to Western Jackdaws migrating there from areas further north.[50] The same data from Warsaw, collected from 1977 to 2003, showed that the wintering Western Jackdaw population had increased four-fold. The cause of the increase is unknown, but a reduction in the number of Rooks may have benefited the species locally, or Rooks overwintering in Belarus may have caused Western Jackdaws to relocate to Warsaw.[51]

Behaviour
Generally wary of people in the forest or countryside, Western Jackdaws are much tamer in urban areas.[52] Like Magpies,[53] they are known to pick up shiny objects such as jewellery to hoard in nests.[54] John Gay, in his Beggar's Opera, notes that "A covetous fellow, like a jackdaw, steals what he was never made to enjoy, for the sake of hiding it".[55] In Tobias Smollett's The Expedition of Humphry Clinker, a scathing character assassination runs, "He is ungracious as a hog, greedy as a vulture, and thievish as a jackdaw."[56]

Highly gregarious, Western Jackdaws are generally seen in flocks of varying sizes, though males and females pair-bond for life and pairs stay together within flocks.[57] Flocks increase in size in autumn and birds congregate at dusk for communal roosting,[12] with up to several thousand individuals gathering at one site. At Uppsala, Sweden, 40,000 birds have been recorded at a single winter roost with mated pairs often settling together for the night. [52] Western Jackdaws frequently congregate with Hooded Crows[33] or Rooks,[35] the latter particularly when migrating or roosting.[58] They have been recorded foraging with the Common Starling (Sturnus vulgaris), Northern Lapwing (Vanellus vanellus), and Common Gull (Larus canus) in northwestern England.[58] Flocks are targets of coordinated hunting by pairs of Lanner Falcons (Falco biarmicus), although larger groups are more able to elude the predators.[59] Western Jackdaws sometimes mob and drive off larger birds such as European Magpies, Common Ravens, or Egyptian Vultures (Neophron percnopterus); one gives an alarm call which alerts its conspecifics to gather and attack as a group.[41] Occasionally, a sick or injured Western Jackdaw is mobbed until it is killed.[60]

In his book King Solomon's Ring, Konrad Lorenz described and analysed the complex social interactions in a Western Jackdaw flock that lived around his house in Altenberg, Austria. He ringed them for identification and caged them in the winter to prevent their annual migration. He found that the birds have a linear hierarchical group structure, with higher-ranked individuals dominating lower-ranked birds, and pair-bonded birds sharing the same rank.[61] Young males establish their individual status before pairing with females. Upon pairing, the female assumes the same social position as her partner. Unmated females are the lowest members in the pecking order, and are the last to have access to food and shelter.[61] Lorenz noted one case in which a male, absent during the dominance struggles and pair bondings, returned to the flock, became the dominant male, and chose one of two unpaired females for a mate. This female immediately assumed a dominant position in the social hierarchy and demonstrated this by pecking others. According to Lorenz, the most significant factor in social behaviour was the immediate and intuitive grasp of the new hierarchy by each of the Western Jackdaws in the flock.[61]

Social displays
Social hierarchy in Western Jackdaw flocks is determined by supplanting, fighting, and threat displays—several of which have been described. In the bill- up posture, the Western Jackdaw tilts its bill and head upwards and sleeks its plumage. Indicating both appeasement and assertiveness, the posture is used by birds intending to enter feeding flocks. A bill-down posture is another commonly used agonistic behaviour. In this display, a bird lowers its bill and erects its nape and head feathers, and sometimes slightly lifts its wings. Western Jackdaws often face off in this posture until one backs down or a fight ensues. In the forward-threat posture, a bird holds its body horizontally and thrusts its head forwards. In intense versions, the bird ruffles its feathers and spreads or raises its tail and wings. This extreme is seen when facing off over nests or females.[62] In the defensive-threat posture, the bird lowers its head and bill, spreads its tail and ruffles its feathers. Supplanting is where one bird moves in and displaces another from a perch-site. The second bird usually retreats without resorting to a fight. Western Jackdaws fight by launching themselves at each other feet-first and then wrestling with their feet intertwined and pecking at each other. Other individuals gather and call noisily.[63]

Western Jackdaws entreat their partners to preen them by showing their nape and ruffling their head feathers. Birds mainly preen each other's head and neck. Known as allopreening, this behaviour is almost always done between birds of a mated pair.[63]

Feeding
Foraging takes place mostly on the ground in open areas and to some extent in trees.[24] Rubbish tips, bins, streets, and gardens are also visited, more often early in the morning when there are fewer people about.[24] Various feeding methods are employed, such as jumping, pecking, clod-turning and scattering, probing the soil, and occasionally, digging. Flies around cow pats are caught by jumping from the ground or at times by dropping vertically from a few metres onto the cow pat. Earthworms are not usually extracted from the ground by Western Jackdaws but are eaten from freshly ploughed soil.[64] Jackdaws will ride on the backs of sheep and other mammals, seeking ticks as well as actively gathering wool or hair for nests, and will catch flying ants in flight.[38] Compared with other corvids, the Western Jackdaw spends more time exploring and turning over objects with its bill; it also has a straighter and less downturned bill and increased binocular vision which are advantageous for this foraging strategy.[65]

The Western Jackdaw tends to feed on small invertebrates up to 18 millimetres (0.71 in) in length that are found above ground, including various species of beetle (particularly cockchafers of the genus Melolontha,[66] and weevil larvae and pupae.[64]), Diptera, and Lepidoptera species, as well as snails and spiders. Also eaten are small rodents, the eggs and chicks of birds, and carrion such as roadkill. Vegetable items consumed include farm grains (barley, wheat and oats), weed seeds, elderberries, acorns, and various cultivated fruits.[64] Examination of the gizzards of Western Jackdaws shot in Cyprus in spring and summer revealed a diet of cereals (predominantly wheat) and insects (notably cicadas and beetles).[67] The diet averages 84% plant material except when breeding, when the main food source is insects.[38] A study in southern Spain examining Western Jackdaw pellets found that they contained significant amounts of silicaceous and calcareous grit to aid digestion of vegetable food and supply dietary calcium.[68]

Opportunistic and highly adaptable, the Western Jackdaw varies its diet markedly depending on available food sources.[69] They have been recorded taking eggs and nestlings from the nests of the Skylark (Alauda arvensis),[70] Manx Shearwater (Puffinus puffinus), Razorbill (Alca torda), Common Murre (Uria aalge), Grey Heron (Ardea cinerea),[66] Rock Pigeon (Columba livia),[71] and Eurasian Collared Dove (Streptopelia decaocto).[66] A field study of a large city dump on the outskirts of León in northwestern Spain showed that Western Jackdaws forage there in the early morning and at dusk, and engage in some degree of kleptoparasitism.[72] The Saker Falcon (Falco cherrug) has been reported stealing food from Western Jackdaws on powerlines in Vojvodina in Serbia.[73]

Western Jackdaws practice active food sharing – where the initiative for the transfer lies with the donor – with a number of individuals, regardless of sex or kinship. They also share more of a preferred food than a less preferred food.[74] The active giving of food by most birds is found mainly in the context of parental care and courtship. Western Jackdaws show much higher levels of active giving than has been documented for other species, including chimpanzees. The function of this behaviour is not fully understood, though it has been found to be detached from nutrition and compatible with hypotheses of mutualism, reciprocity and harassment avoidance. It has also been proposed that food sharing may be motivated by prestige enhancement.[75]

Breeding
Western Jackdaws become sexually mature in their second year. Genetic analysis of pairs and offspring shows no evidence of extra-pair copulation [57] and there is little evidence for couple separation even after multiple instances of reproductive failure.[76] Some pairs do separate in the first few months, but almost all pairings of over six months' duration are lifelong, ending only when a partner dies.[58] Widowed or separated birds fare badly, often being ousted from nests or territories and unable to rear broods alone.[58]

Western Jackdaws usually breed in colonies with pairs collaborating to find a nest site, which they then defend from other pairs and predators during most of the year.[76] They nest in cavities in trees or cliffs, in ruined or occupied buildings and in chimneys, the common feature being a sheltered site for the nest. The availability of suitable sites influences their presence in a locale.[35] They may also use church steeples for nesting, a fact reported in verse by 18th century English poet William Cowper:

A great frequenter of the church,
Where, bishoplike, he finds a perch,
And dormitory too.[77]

A mated pair usually constructs a nest by improving crevice by dropping sticks into it; it is then built on top of the platform formed.[60] This behaviour has led to the blocking of chimneys and even resulted in nests crashing down into fireplaces, sometimes with birds still on them.[78] Nest platforms can attain a great size. John Mason Neale notes that a "Clerk was allowed by the Churchwarden to have for his own use all that the caddows had brought into the Tower: and he took home, at one time, two cart-loads of good firewood, besides a great quantity of rubbish which he threw away."[79] In his The Natural History of Selborne, Gilbert White notes that Western Jackdaws used to nest in crevices beneath the lintels of Stonehenge, and describes an example of the bird using a rabbit burrow for nesting.[17] The species has been recorded outcompeting the Tawny Owl (Strix aluco) for nest sites in the Netherlands. [80] They can take over old nest sites of the Black Woodpecker (Dryocopus martius) [81] and Stock Dove (Columba oenas).[63] Breeding colonies may also edge out those of the Red-billed Chough, but in turn be ousted by larger corvids such as the Carrion Crow, Rook or Magpie.[63]

Nests are lined with hair, wool, dead grass and many other materials.[82] The eggs are a lighter colour than those of other corvids,[83] being smooth, a glossy pale blue or blue-green with darker speckles ranging from dark brown to olive or grey-violet.[84] Egg size and weight varies slightly between subspecies; those of subspecies monedula average 35.0 by 24.7 millimetres (1.38 in × 0.97 in) and 11.1 g (0.39 oz) in weight, those of subspecies soemmerringii 34.8 by 25.0 millimetres (1.37 in × 0.98 in) in size and 11.3 g (0.40 oz) in weight, and those of subspecies spermologus 35.0 by 25.2 millimetres (1.38 in × 0.99 in) in size and 11.5 g (0.41 oz) in weight.[84] Clutches usually contain 4 or 5 eggs,[82] although a Slovakian study found clutch sizes ranging from 2 to 9 eggs.[85] The eggs are incubated by the female for 17–18 days until hatching as naked altricial chicks, which are completely dependent on the adults for food. They fledge after 28–35 days,[82] and the parents continue to feed them for another four weeks or so.[58]

Western Jackdaws hatch asynchronously and incubation begins before clutch completion, which often leads to the death of the last-hatched young. If the supply of food is low, parental investment in the brood is kept to a minimum as little energy is wasted on feeding a chick that is unlikely to survive.[86] Replacement clutches are very rarely laid in the event of clutch failure.[84]

The Great Spotted Cuckoo (Clamator glandarius) has been recorded as a brood parasite of the Western Jackdaw, depositing its eggs in their nests in Spain and Israel.[87][88] Nest robbers include the Common Raven in Spain, Tawny Owl, and least weasel (Mustela nivalis) in England, and brown rat (Rattus norvegicus) in Finland.[89] The European pine marten (Martes martes) raids isolated nests in Sweden but is less successful when nests are part of a colony.[81]

Parasites and diseases
Western Jackdaws have learned to peck open the foil caps of milk bottles left on the doorsteps after delivery by the milkman. The bacterium Campylobacter jejuni has been isolated from their beaks and cloacae so milk can become contaminated as they drink. This activity was linked to cases of Campylobacter gastroenteritis in Gateshead in northeast England [90] and led the Department of Health to suggest that milk from bottles which had been pecked open should be discarded. It was recommended that steps be taken to prevent birds attacking bottles in future.[91]

An outbreak of a gastrointestinal illness in Spain which was causing mortalities in humans has been linked to Western Jackdaws. During a post-mortem on an affected bird, a polyomavirus was isolated from the spleen. The illness appeared to be a co-infection of this with Salmonella and the virus has been provisionally named the crow polyomavirus (CPyV).[92] Segmented filamentous bacteria have been isolated from the small intestine of a Western Jackdaw, although their pathogenicity or role is unknown.[93]

Pest control
The Western Jackdaw has been hunted as vermin, though not as heavily culled as other species of corvid.[108] After a series of poor harvests in the early 1500s, Henry VIII introduced a Vermin Act in 1532 "ordeyned to dystroye Choughes (i.e. Jackdaws), Crowes and Rokes" to protect grain crops from their predations. Western Jackdaws were notorious as they also favoured fruit, especially cherries. This act was taken up in a piecemeal fashion, but Elizabeth I passed the Act for the Preservation of Grayne in 1566 that was taken up with more vigour. The species was hunted for its threat to grain crops and for propensity for nesting in belfries until the mid-20th century. Particularly large numbers were culled in the county of Norfolk. Western Jackdaws were also culled on game estates as they raid nests of other birds for eggs.[109] In a 2003 dissertation on public opinion of corvids, Antonia Hereth notes that the German naturalist Alfred Brehm considered the Western Jackdaw to be a lovable bird, and did not describe any negative impacts of this species on agriculture.[110]

The Western Jackdaw is one of a very small number of birds that it is legal to use as a decoy or to trap in a cage in the United Kingdom. The other pest species that can be controlled by trapping are the Crow, Jay, Magpie and Rook. An authorised person must comply with the requirements of the Wildlife and Countryside Act 1981 and does not need to show that the birds were a nuisance before trapping them.[111] As of 2003 the Western Jackdaw was listed as a potential species for targeted hunting in the European Union Birds Directive, and hunting has been encouraged by German hunting associations.[110] Permission to shoot Western Jackdaws in spring and summer exists in Cyprus as they are thought (incorrectly) to prey on gamebirds. [67]

ref.:
Jackdaw (Wikipedia)

Jackdaw (Google)

Jackdaw (Google Pics)

Jackdaw (YouTube)

The voice (Coloeus monedula)

 

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Red-billed Chough
Pyrrhocorax pyrrhocorax, da. Alpekrage
Deutsch: Alpenkrähe
English: Red-billed Chough
Français: Crave à bec rouge

Red-billed Chough
The Red-billed Chough or Chough ( /'t??f/ CHUFF), Pyrrhocorax pyrrhocorax, is a bird in the crow family, one of only two species in the genus Pyrrhocorax. Its eight subspecies breed on mountains and coastal cliffs from the western coasts of Ireland and Britain east through southern Europe and North Africa to Central Asia, India and China.

This bird has glossy black plumage, a long curved red bill, red legs, and a loud, ringing call. It has a buoyant acrobatic flight with widely spread primaries. The Red-billed Chough pairs for life and displays fidelity to its breeding site, which is usually a cave or crevice in a cliff face. It builds a wool-lined stick nest and lays three eggs. It feeds, often in flocks, on short grazed grassland, taking mainly invertebrate prey.

Although it is subject to predation and parasitism, the main threat to this species is changes in agricultural practices, which have led to population decline, some local extirpation, and range fragmentation in Europe; however, it is not threatened globally. The Red-billed Chough, which derived its common name from the Jackdaw, was formerly associated with fire-raising, and has links with Saint Thomas Becket and the county of Cornwall. The Red-billed Chough has been depicted on postage stamps of a few countries, including the Isle of Man, with four different stamps, and The Gambia, where the bird does not occur.

Taxonomy
The Red-billed Chough was first described by Linnaeus in his Systema Naturae in 1758 as Upupa pyrrhocorax.[2] It was moved to its current genus, Pyrrhocorax, by Marmaduke Tunstall in his 1771 Ornithologia Britannica.[3] The genus name is derived from Greek p????? (purrhos), "flame-coloured", and ???a? (korax), "raven".[4] The only other member of the genus is the Alpine Chough, Pyrrhocorax graculus.[5] The closest relatives of the choughs are the typical crows, Corvus, especially the jackdaws in the subgenus Coloeus.[6]

"Chough" was originally an alternative onomatopoeic name for the Jackdaw, Corvus monedula, based on its call. The similar red-billed species, formerly particularly common in Cornwall, became known initially as "Cornish Chough" and then just "Chough", the name transferring from one species to the other.[7] The Australian White-winged Chough, Corcorax melanorhamphos, despite its similar shape and habits, is only distantly related to the true choughs, and is an example of convergent evolution.[8]

Subspecies
There are eight extant subspecies, although differences between them are slight.[9]
• P. p. pyrrhocorax, the nominate subspecies and smallest form, is endemic to the British Isles, where it is restricted to Ireland, the Isle of Man, and the far west of Wales and Scotland,[9] although it recolonised Cornwall in 2001 after an absence of 50 years.[10]
• P. p. erythropthalmus, described by Louis Jean Pierre Vieillot in 1817 as Coracia erythrorhamphos,[11] occurs in the Red-billed Chough's continental European range, excluding Greece. It is larger and slightly greener than the nominate race.[9]
• P. p. barbarus, described by Charles Vaurie under its current name in 1954, is resident in North Africa and on La Palma in the Canary Islands. Compared to P. p. erythropthalmus, it is larger, has a longer tail and wings, and its plumage has a greener gloss. It is the longest-billed form, both absolutely and relatively.[12]
• P. p. baileyi described by Austin Loomer Rand and Charles Vaurie under its current name in 1955,[13] is a dull-plumaged subspecies endemic to Ethiopia, where it occurs in two separate areas. The two populations could possibly represent different subspecies.[9]
• P. p. docilis, described by Johann Friedrich Gmelin as Corvus docilis in 1774,[14] breeds from Greece to Afghanistan. It is larger than the African subspecies, but it has a smaller bill and its plumage is very green-tinted, with little gloss.[9]
• P. p. himalayanus, described by John Gould in 1862 as Fregilus himalayanus,[15] is found from the Himalayas to western China, but intergrades with P. p. docilis in the west of its range. It is the largest subspecies, long-tailed, and with blue or purple-blue glossed feathers.[9]
• P. p. centralis, described by Erwin Stresemann in 1928 under its current name,[16] breeds in central Asia. It is smaller and less strongly blue than P. p. himalayanus,[9] but its distinctness from the next subspecies has been questioned.[12]
• P. p. brachypus, described by Robert Swinhoe in 1871 as Fregilus graculus var. brachypus,[17] breeds in central and northern China, Mongolia and southern Siberia. It is similar to P. p. centralis but with a weaker bill.[9]
There is one known prehistoric form of the Red-billed Chough. P. p. primigenius, a subspecies that lived in Europe during the last ice age, which was described in 1875 by Alphonse Milne-Edwards from finds in southwest France.[18][19]
Detailed analysis of call similarity suggests that the Asiatic and Ethiopian races diverged from the western subspecies early in evolutionary history, and that Italian Red-billed Choughs are more closely allied to the North African subspecies than to those of the rest of Europe.[20]

Description
The adult of the "nominate" subspecies of the Red-billed Chough, P. p. pyrrhocorax, is 39–40 centimetres (15–16 in) in length, has a 73–90 centimetres (29–35 in) wingspan,[21] and weighs an average 310 grammes (10.9 oz).[4] Its plumage is velvet-black, green-glossed on the body, and it has a long curved red bill and red legs. The sexes are similar (although adults can be sexed in the hand using a formula involving tarsus length and bill width)[22] but the juvenile has an orange bill and pink legs until its first autumn, and less glossy plumage.[9]

The Red-billed Chough is unlikely to be confused with any other species of bird. Although the Jackdaw and Alpine Chough share its range, the Jackdaw is smaller and has unglossed grey plumage, and the Alpine Chough has a short yellow bill. Even in flight, the two choughs can be distinguished by Alpine's less rectangular wings, and longer, less square-ended tail.[9]

The Red-billed Chough's loud, ringing chee-ow call is clearer and louder than the similar vocalisation of the Jackdaw, and always very different from that of its yellow-billed congener, which has rippling preep and whistled sweeeooo calls.[9] Small subspecies of the Red-billed Chough have higher frequency calls than larger races, as predicted by the inverse relationship between body size and frequency.[23]

Distribution and habitat
The Red-billed Chough breeds in Ireland, western Great Britain, the Isle of Man, southern Europe and the Mediterranean basin, the Alps, and in mountainous country across Central Asia, India and China, with two separate populations in the Ethiopian Highlands. It is a non-migratory resident throughout its range.[9]

Its main habitat is high mountains; it is found between 2,000 and 2,500 metres (6,560–8,200 ft) in North Africa, and mainly between 2,400 and 3,000 metres (7,950–9,840 ft) in the Himalayas. In that mountain range it reaches 6,000 metres (19,650 ft) in the summer, and has been recorded at 7,950 metres (26,080 ft) altitude on Mount Everest.[9] In Ireland, Great Britain and Brittany it also breeds on coastal sea cliffs, feeding on adjacent short grazed grassland or machair. It was formerly more widespread on coasts but has suffered from the loss of its specialised habitat.[24][25] It tends to breed at a lower elevation than the Alpine Chough,[21] that species having a diet better adapted to high altitudes.[26]

Breeding
The Red-billed Chough breeds from three years of age, and normally raises only one brood a year,[4] although the age at first breeding is greater in large populations.[27] A pair exhibits strong mate and site fidelity once a bond is established.[28] The bulky nest is composed of roots and stems of heather, furze or other plants, and is lined with wool or hair;[21] in central Asia, the hair may be taken from live Himalayan Tahr.[29] The nest is constructed in a cave or similar fissure in a crag or cliff face.[21] In soft sandstone, the birds themselves excavate holes nearly a metre deep.[30] Old buildings may be used, and in Tibet working monasteries provide sites, as occasionally do modern buildings in Mongolian towns, including Ulan Bator.[9] The Red-billed Chough will utilise other artificial sites sites such as quarries and mineshafts for nesting where they are available.[31]

The Chough lays three to five eggs 3.9 x 2.8 centimetres (1.5 x 1.1 in) in size and weighing 15.7 grammes (0.55 oz), of which 6% is shell.[4] They are spotted, not always densely, in various shades of brown and grey on a creamy or slightly tinted ground.[21]

The egg size is independent of the clutch size and the nest site, but may vary between different females.[32] The female incubates for 17–18 days before the altricial downy chicks are hatched, and is fed at the nest by the male. The female broods the newly hatched chicks for around ten days,[33] and then both parents share feeding and nest sanitation duties. The chicks fledge 31–41 days after hatching.[4]

Juveniles have a 43% chance of surviving their first year, and the annual survival rate of adults is about 80%. Choughs generally have a lifespan of about seven years,[4] although an age of 17 years has been recorded.[28] The temperature and rainfall in the months preceding breeding correlates with the number of young fledging each year and their survival rate. Chicks fledging under good conditions are more likely to survive to breeding age, and have longer breeding lives than those fledging under poor conditions.[27]

Feeding
The Red-billed Chough's food consists largely of insects, spiders and other invertebrates taken from the ground, with ants probably being the most significant item.[9] The Central Asian subspecies P. p. centralis will perch on the backs of wild or domesticated mammals to feed on parasites.[29] Although invertebrates make up most of the Chough's diet, it will eat vegetable matter including fallen grain, and in the Himalayas has been reported as damaging barley crops by breaking off the ripening heads to extract the corn.[9] In the Himalayas, they form large flocks in winter.[34]

The preferred feeding habitat is short grass produced by grazing, for example by sheep and rabbits, the numbers of which are linked to the Chough's breeding success. Suitable feeding areas can also arise where plant growth is hindered by exposure to coastal salt spray or poor soils.[35][36] It will use its long curved bill to pick ants, dung beetles and emerging flies off the surface, or to dig for grubs and other invertebrates. The typical excavation depth of 2–3 cm (0.8–1.2 in) reflects the thin soils which it feeds on, and the depths at which many invertebrates occur, but it may dig to 10–20 cm (4–8 in) in appropriate conditions.[37][38]

Where the two chough species occur together, there is only limited competition for food. An Italian study showed that the vegetable part of the winter diet for the Red-billed Chough was almost exclusively Gagea bulbs, whilst the Alpine Chough took berries and hips. In June, Red-billed Choughs fed on Lepidoptera larvae whereas Alpine Choughs ate cranefly pupae. Later in the summer, the Alpine Chough mainly consumed grasshoppers, whilst the Red-billed Chough added cranefly pupae, fly larvae and beetles to its diet.[26] Both choughs will hide food in cracks and fissures, concealing the cache with a few pebbles.[39]

Natural threats
The Red-billed Chough's predators include the Peregrine Falcon, Golden Eagle and Eurasian Eagle-owl, while the Common Raven will take nestlings.[40] [41][42][43] In northern Spain, Red-billed Choughs preferentially nest near Lesser Kestrel colonies. This small insectivorous falcon is better at detecting a predator and more vigorous in defence than its corvid neighbours. The breeding success of the Red-billed Chough in the vicinity of the kestrels was found to be much higher than that of birds elsewhere, with a lower percentage of nest failures (16% near the falcon, 65% elsewhere).[43]

This species is occasionally parasitised by the Great Spotted Cuckoo, a brood parasite for which the Eurasian Magpie is the primary host.[44] Red-billed Choughs can acquire blood parasites such as Plasmodium, but a study in Spain showed that the prevalence was less than one percent, and unlikely to affect the life history and conservation of this species.[45] These low levels of parasitism contrast with a much higher prevalence in some other passerine groups; for example a study of thrushes in Russia showed that all the Fieldfares, Redwings and Song Thrushes sampled carried haematozoans, particularly Haemoproteus and Trypanosoma.[46]

Red-billed Choughs can also carry mites, but a study of the feather mite Gabucinia delibata, acquired by young birds a few months after fledging when they join communal roosts, suggested that this parasite actually improved the body condition of its host. It is possible that the feather mites enhance feather cleaning and deter pathogens,[47] and may complement other feather care measures such as sunbathing, and anting—rubbing the plumage with ants (the formic acid from the insects deters parasites).[9]

Status
The Red-billed Chough has an extensive range, estimated at 10 million square kilometres (3.8 million sq mi), and a large population, including an estimated 86,000 to 210,000 individuals in Europe. Over its range as a whole, the species is not believed to approach the thresholds for the global population decline criterion of the IUCN Red List (i.e., declining more than 30% in ten years or three generations), and is therefore evaluated as Least Concern.[1]

However, the European range has declined and fragmented due to the loss of traditional pastoral farming, persecution and perhaps disturbance at breeding and nesting sites, although the numbers in France, Great Britain and Ireland may now have stabilised.[21] The European breeding population is between 12,265–17,370 pairs, but only in Spain is the species still widespread. Since in the rest of the continent breeding areas are fragmented and isolated, the Red-billed Chough has been categorised as "vulnerable" in Europe.[31]

In Spain, the Red-billed Chough has recently expanded its range by utilising old buildings, with 1,175 breeding pairs in a 9,716 square kilometre (3,692 sq mi) study area. These new breeding areas usually surround the original montane core areas. However, the populations with nest sites on buildings are threatened by human disturbance, persecution and the loss of old buildings.[48] Fossils of both chough species were found in the mountains of the Canary Islands. The local extinction of the Alpine Chough and the reduced range of Red-billed Chough in the islands may have been due to climate change or human activity.[49]

A small group of wild Red-billed Chough arrived naturally in Cornwall in 2001, and nested in the following year. This was the first English breeding record since 1947, and a slowly expanding population has bred every subsequent year.[25]

In Jersey, the Durrell Wildlife Conservation Trust, in partnership with the States of Jersey and the National Trust for Jersey began a project in 2010, aimed at restoring selected areas of Jersey’s coastline with the intention of returning those birds that had become locally extinct. The Red-billed Chough was chosen as a flagship species for this project, having been absent from Jersey since around 1900. Durrell initially received two pairs of choughs from Paradise Park in Cornwall and began a captive breeding programme. In 2012, the Red-billed Choughs were living free in the central valley area of Durrell Wildlife Park, and the Trust expects colonisation of the coastal areas of Jersey in the following years.[50]

ref.:
Red-billed Chough (Wikipedia)

Red-billed Chough (Google)

Red-billed Chough (Google Pics)

Red-billed Chough (YouTube)

The voice (Pyrrhocorax pyrrhocorax)

 

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Alpine Chough
Pyrrhocorax graculus, da. Alpeallike
Deutsch: Alpendohle

Photo: Jim Higham

large pic.

Alpine Chough
The Alpine Chough ( /'t??f/), or Yellow-billed Chough, (Pyrrhocorax graculus) is a bird in the crow family, one of only two species in the genus Pyrrhocorax. Its two subspecies breed in high mountains from Spain east through southern Europe and North Africa to Central Asia, India and China, and it may nest at a higher altitude than any other bird. The eggs have adaptations to the thin atmosphere that improve oxygen take-up and reduce water loss.

This bird has glossy black plumage, a yellow bill, red legs, and distinctive calls. It has a buoyant acrobatic flight with widely spread flight feathers. The Alpine Chough pairs for life and displays fidelity to its breeding site, which is usually a cave or crevice in a cliff face. It builds a lined stick nest and lays three to five brown-blotched whitish eggs. It feeds, usually in flocks, on short grazed grassland, taking mainly invertebrate prey in summer and fruit in winter; it will readily approach tourist sites to find supplementary food.

Although it is subject to predation and parasitism, and changes in agricultural practices have caused local population declines, this widespread and abundant species is not threatened globally. Climate change may present a long-term threat, by shifting the necessary alpine habitat to higher altitudes.

Taxonomy
The Alpine Chough was first described as Corvus graculus by Linnaeus in the Systema Naturae in 1766.[2] It was moved to its current genus, Pyrrhocorax, by English ornithologist Marmaduke Tunstall in his 1771 Ornithologia Britannica,[3] along with the only other member of the genus, the Red- billed Chough, P. pyrrhocorax.[4] The closest relatives of the choughs were formerly thought to be the typical crows, Corvus, especially the jackdaws in the subgenus Coloeus,[5] but DNA and cytochrome b analysis shows that the genus Pyrrhocorax, along with the Ratchet-tailed Treepie (genus Temnurus), diverged early from the rest of the Corvidae.[6]

The genus name is derived from Greek p????? (purrhos), "flame-coloured", and ???a? (korax), "raven".[7] The species epithet graculus is Latin for a jackdaw.[8] The current binomial name of the Alpine Chough was formerly sometimes applied to the Red-billed Chough.[9][10] The English word "chough" was originally an alternative onomatopoeic name for the Jackdaw, Corvus monedula, based on its call. The Red-billed Chough, formerly particularly common in Cornwall and known initially as the "Cornish Chough", eventually became just "Chough", the name transferring from one genus to another. [11]

The Alpine Chough has two extant subspecies.

• P. g. graculus, the nominate subspecies in Europe, north Africa, Turkey, the Caucusus and northern Iran.[4]
• P. g. digitatus, described by the German naturalists Wilhelm Hemprich and Christian Gottfried Ehrenberg as P. alpinus var. digitatus in 1833,[12] is larger and has stronger feet than the nominate race.[4] It breeds in the rest of the depicted Asian range, mainly in the Himalayas.[13]
Moravian palaeontologist Ferdinand Stoliczka separated the Himalayan population as a third subspecies, P. g. forsythi,[14] but this has not been widely accepted and is usually treated as synonymous with digitatus.[15][16] A Pleistocene form from Europe was similar to the extant subspecies, and is sometimes categorised as P. g. vetus.[17][18][19]

The Australian White-winged Chough, Corcorax melanorhamphos, despite its similar bill shape and black plumage, is only distantly related to the true choughs.[20]

Description The adult of the nominate subspecies of the Alpine Chough has glossy black plumage, a short yellow bill, dark brown irises, and red legs.[4] It is slightly smaller than Red-billed Chough, at 37–39 centimetres (14.6–15.3 in) length with a 12–14 cm (4.7–5.5 in) tail and a 75–85 cm (30–33 in) wingspan, but has a proportionally longer tail and shorter wings than its relative. It has a similar buoyant and easy flight.[13] The sexes are identical in appearance although the male averages slightly larger than the female. The juvenile is duller than the adult with a dull yellow bill and brownish legs.[4] The Alpine Chough is unlikely to be confused with any other species; although the Jackdaw and Red-billed Chough share its range, the Jackdaw is smaller and has unglossed grey plumage, and the Red-billed Chough has a long red bill.[13]

The subspecies P. g. digitatus averages slightly larger than the nominate form, weighing 191–244 grams (6.8–8.7 oz) against 188–252 g (6.7–9.0 oz) for P. g. graculus, and it has stronger feet.[4][13] This is in accordance with Bergmann's rule, which predicts that the largest birds should be found higher elevations or in colder and more arid regions. The extremities of the body, the bill and tarsus, were longer in warmer areas, in line with Allen's rule. Temperature seemed to be the most important cause of body variation in the Alpine Chough.[21]

The flight of the Alpine Chough is swift and acrobatic with loose deep wing beats. Its high manoeuvrability is accomplished by fanning the tail, folding its wings, and soaring in the updraughts at cliff faces. Even in flight, it can be distinguished from Red-billed Chough by its less rectangular wings, and longer, less square-ended tail.[13][22]

The rippling preep and whistled sweeeooo calls of the Alpine Chough are quite different from the more typically crow-like chee-ow vocalisations of the Jackdaw and the Red-billed Chough. It also has a rolling churr alarm call, and a variety of quiet warbles and squeaks given by resting or feeding birds.[4] In a study of chough calls throughout the Palearctic region it was found that call frequencies in the Alpine Chough showed an inverse relationship between body size and frequency, being higher-pitched in smaller-bodied populations.[23]

Distribution and habitat
The Alpine Chough breeds in mountains from Spain eastwards through southern Europe and the Alps across Central Asia and the Himalayas to western China. There are also populations in Morocco, Corsica and Crete. It is a non-migratory resident throughout its range, although Moroccan birds have established a small colony near Málaga in southern Spain, and wanderers have reached Czechoslovakia, Gibraltar, Hungary and Cyprus.[4]

This is a high-altitude species normally breeding between 1,260–2,880 metres (4,130–9,450 ft) in Europe, 2,880–3,900 m (9,450–12,800 ft) in Morocco, and 3,500–5,000 m (11,500–16,000 ft) in the Himalayas.[4] It has nested at 6,500 m (21,300 ft), higher than any other bird species,[24] even surpassing the Red-billed Chough which has a diet less well adapted to the highest altitudes.[25] It has been observed following mountaineers ascending Mount Everest at an altitude of 8,200 m (26,900 ft).[26] It usually nests in cavities and fissures on inaccessible rock faces, although locally it will use holes between rocks in fields,[27] and forages in open habitats such as alpine meadows and scree slopes to the tree line or lower, and in winter will often congregate around human settlements, ski resorts, hotels and other tourist facilities.[13] Its penchant for waiting by hotel windows for food is popular with tourists, but less so with hotel owners.[5]

Breeding
The Alpine Chough is socially monogamous, showing high partner fidelity in summer and winter and from year to year.[28] Nesting typically starts in early May, and is non-colonial, although in suitable habitat several pairs may nest in close proximity.[4] The bulky nests are composed of roots, sticks and plant stems lined with grass, fine twiglets or hair, and may be constructed on ledges, in a cave or similar fissure in a cliff face, or in an abandoned building. The clutch is 3–5 glossy whitish eggs, averaging 33.9 by 24.9 millimetres (1.33 in × 0.98 in) in size,[29] which are tinged with buff, cream or light-green and marked with small brown blotches;[4] they are incubated by the female for 14–21 days before hatching.[13] The chicks hatch with a dense covering of natal down, in contrast to those of the Red-billed Chough which are almost naked,[30] and fledge in a further 29–31 days from hatching.[13] The young birds are fed by both parents, and may also be fed by other adults when they have fledged and joined the flock.[4] Breeding is possible in the high mountains because chough eggs have relatively fewer pores than those of lowland species, and lose less water by evaporation at low atmospheric pressure.[31] The embryos of bird species that breed at high altitude also have haemoglobin with a genetically determined high affinity for oxygen.[32]

In the western Italian Alps, the Alpine Chough nests in a greater variety of sites than Red-billed Chough, using natural cliffs, pot-holes and abandoned buildings, whereas the Red-billed uses only natural cliffs (although it nests in old buildings elsewhere).[4][25][33] The Alpine Chough lays its eggs about one month later than its relative, although breeding success and reproductive behaviour are similar. The similarities between the two species presumably arose because of the same strong environmental constraints on breeding behaviour.[25]

A study of three different European populations showed a mean clutch size of 3.6 eggs, producing 2.6 chicks, of which 1.9 fledged. Adult survival rate varied from 83 to 92%, with no significant difference detected between males and females. Survival of first-year birds was, at 77%, lower than that of adults. The availability or otherwise of human food supplied from tourist activities did not affect breeding success.[28]

Feeding
In the summer, the Alpine Chough feeds mainly on invertebrates collected from pasture, such as beetles (Selatosomus aeneus and Otiorhynchus morio have been recorded from pellets), snails, grasshoppers, caterpillars and fly larvae.[5] The diet in autumn, winter and early spring becomes mainly fruit, including berries such as the European Hackberry (Celtis australis) and Sea-buckthorn (Hippophae rhamnoides),[5] rose hips, and domesticated crops such as apples, grapes and pears where available.[34] It has been observed eating flowers of Crocus vernus albiflorus, including the pistils, perhaps as a source of carotenoids.[35] The chough will readily supplement its winter diet with food provided by tourist activities in mountain regions, including ski resorts, refuse dumps and picnic areas. Where additional food is available, winter flocks are larger and contain a high proportion of immature birds. The young birds principally frequent the sites with the greatest food availability, such as refuse dumps.[36] Both chough species will hide food in cracks and fissures, concealing the cache with a few pebbles.[37]

This bird always forages in groups, which are larger in winter than summer, and have constant composition in each season. Where food resources are restricted, adults dominate young birds, and males outrank females.[28] Foraging areas change altitudinally through the year, depending on climatic factors, food availability and food quality. During the breeding season, birds remain above the tree line, although they may use food provided by tourists at refuges and picnic areas.[34]

Movement to lower levels begins after the first snowfalls, and feeding by day is mainly in or near valley bottoms when the snow cover deepens, although the birds return to the mountains to roost. In March and April the choughs frequent villages at valley tops or forage in snow-free patches prior to their return to the high meadows.[34] Feeding trips may cover 20 km (12 mi) distance and 1,600 m (5,200 ft) in altitude. In the Alps, the development of skiing above 3,000 m (9,800 ft) has enabled more birds to remain at high levels in winter.[13]

Where their ranges overlap, the two chough species may feed together in the summer, although there is only limited competition for food. An Italian study showed that the vegetable part of the winter diet for the Red-billed Chough was almost exclusively Gagea bulbs dug from the ground, whilst the Alpine Chough took berries and hips. In June, Red-billed Choughs fed mainly on caterpillars whereas Alpine Choughs ate crane fly pupae. Later in the summer, the Alpine Chough consumed large numbers of grasshoppers, while the Red-billed Chough added cranefly pupae, fly larvae and beetles to its diet.[25] In the eastern Himalayas in November, Alpine Choughs occur mainly in juniper forests where they feed on juniper berries, differing ecologically from the Red-billed Choughs in the same region and at the same time of year, which feed by digging in the soil of terraced pastures of villages.[38]

Natural threats
Predators of the choughs include the Peregrine Falcon, Golden Eagle and Eurasian Eagle-owl, while the Common Raven will take nestlings.[39][40][41] [42] Alpine Choughs have been observed diving at a Tibetan red fox. It seems likely that this "mobbing" behaviour may be play activity to give practice for when genuine defensive measures may be needed to protect eggs or young.[43]

The Alpine Chough is a host of the widespread bird flea Ceratophyllus vagabunda, two specialist chough fleas Frontopsylla frontalis and F. laetus,[44] a cestode Choanotaenia pirinica,[45] and various species of chewing lice in the genera Brueelia, Menacanthus and Philopterus.[46]

Status
The Alpine Chough has an extensive though sometimes fragmented range, estimated at 1–10 million square kilometres (0.4–3.8 million sq mi), and a large population, including an estimated 260,000 to 620,000 individuals in Europe. The Corsican population has been estimated to comprise about 2,500 birds.[47] Over its range as a whole, the species is not believed to approach the thresholds for the global population decline criteria of the IUCN Red List (i.e., declining more than 30% in ten years or three generations), and is therefore evaluated as Least Concern.[1]

At the greatest extent of the last glacial period around 18,000 years ago, southern Europe was characterised by cold open habitats, and the Alpine Chough was found as far as south as southern Italy, well outside its current range.[48] Some of these peripheral prehistoric populations persisted until recently, only to disappear within the last couple of centuries. In the Polish Tatra Mountains, where a population had survived since the glacial period, it was not found as a breeding bird after the 19th century.[49] In Bulgaria, the number of breeding sites fell from 77 between 1950 and 1981 to just 14 in the 1996 to 2006 period, and the number of pairs in the remaining colonies were much smaller. The decline was thought to be due to the loss of former open grasslands which had reverted to scrubby vegetation once extensive cattle grazing ceased.[50] Foraging habitat can also be lost to human activities such as the construction of ski resorts and other tourist development on former alpine meadows.[51] Populations of choughs are stable or increasing in areas where traditional pastoral or other low intensity agriculture persists, but are declining or have become locally extinct where intensive farming methods have been introduced, such as Brittany, England, south-west Portugal and mainland Scotland.[52]

Choughs can be locally threatened by the accumulation of pesticides and heavy metals in the mountain soils, heavy rain, shooting and other human disturbances,[50] but a longer-term threat comes from global warming, which would cause the species' preferred Alpine climate zone to shift to higher, more restricted areas, or locally to disappear entirely.[53] Fossils of both chough species were found in the mountains of the Canary Islands. The local extinction of the Alpine Chough and the reduced range of Red-billed Chough in the islands may have been due to climate change or human activity.[54]

ref.:

Alpine Chough (Wikipedia)

Alpine Chough (Google)

Alpine Chough (Google Pics)

Alpine Chough (YouTube)

The voice (Corvus graculus)

 

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American Crow
Corvus brachyrhynchos, da. Amerikansk Krage
Also known as Common Crow.

American Crow, Corvus brachyrhynchos
Shark Inlet, Los Osos, California, 2009, May 25
Fotograf: ukendt

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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.

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.

Description
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)

The voice (Corvus brachyrhynchos)

 

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Northwestern Crow
Corvus caurinus, da. Kystkrage

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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)

The voice (Corvus caurinus)

 

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Sinaloa Crow
Corvus sinaloae, da. Sinaloakrage

Sinaloa Crow, Corvus sinaloae
Foto: Jerry Oldenettel

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)

Sinaloa Crow (YouTube)

The voice (Corvus sinaloae)

 

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Chihuahuan Raven
Corvus cryptoleucus, da. Chihuahuaravn
Previously called American White-necked Raven

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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)

Corvus cryptoleucus (Google Pics)

Chihuahuan Raven (YouTube)

The voice (Corvus cryptoleucus)

 

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Tamaulipas Crow
Corvus imparatus, da. Taumalipaskrage
Previously called Mexican Crow.

Tamaulipas Crow, Corvus imparatus
Foto: Joe Fuhman

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)

The voice (Corvus imparatus)

 

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Fish Crow
Corvus ossifragus, da. 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)

The voice (Corvus ossifragus)

 

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