The family Corvidae consists of about 130 species that vary in size from eighteen to seventy centimetres. Corvidae includes the largest Passerine birds.
They are one of the most familiar to people throughout the world due to their success. Crows are as common in nursery rhymes as they are in history and as much a subject of folklore and legend as any other avian family. Magpies are noted for thieving, jackdaws for intelligence, crows for fearlessness, while Britain is said to be doomed if the raven ever leaves the Tower of London. The more obvious species are black, and people have always associated black cats and birds with magic.
Ravens, crows and magpies have often been seen as birds of ill-omen, perhaps because of their colour and size, their perceived intelligence and their raucous cries. The raven was believed to have the power of foretelling death.
They have proved an enormously successful family despite endless persecution, found around the world except New Zealand and Polynesia. Several species exhibit a high level of social behaviour that is otherwise unknown in the bird world.
In Europe, the family is represented by the raven, carrion and hooded crows, rook and jackdaw; in southern Asia, by the house crow and jungle crow among others; and in Africa, by the pied crow, white-necked raven and others. In North America and again in Australia, there are several all-black crows that resemble each other rather closely in structure and appearance but differ in their voices.
Thus the American crow, fish crow, Sinaloan crow, and Mexican crow are more readily separable by their voice than appearance. In Australia, the Australian crow, little crow, Australian raven and others are difficult to identify except by their calls. The genus Corvus has been more successful than others of the family in colonising remote islands, resulting in development of species with local distributions in the West Indies, Indonesia, the southwest Pacific and Hawaii.
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Description
The plumage may be black, black and white, or brilliantly coloured with various green, yellow, blue, purple, and brown combinations. Male and females are usually very similar. The head may be ornamented with a crest or tufts of different shapes and sizes. The tail varies from quite short to very long among such a large family and is graduated in some magpie species. The wings may be pointed or rounded, depending on how far they migrate. However, most species are residents.
The shape of the bill depends on the feeding habits, but it is always sturdy, hooked and covered at the base with feathers. They have strong legs with robust claws, adapted both for perching and for walking on the ground.
Intelligence
The family Corvidae represents one of the more developed stages in the evolution of birds. The species have achieved an extraordinary level of mental development. Many species have taken advantage of living alongside man and have succeeded in extending their range and increasing their numbers, something which even the most advanced mammals have not done.
Corvidae is one of the most successful families of birds, which can be seen in their versatile behaviour, elaborate social structure, distribution and the vast number of species.
Nesting
Nesting may take place in thickly-populated colonies but also in isolation, even with species that are gregarious at other times of the year. The nest is made of a structure of sticks and twigs, situated in trees, bushes, buildings or on cliffs. Some species of Corvidae build a dome-shaped nest.
The number of eggs in a clutch varies depending on the climate and surroundings. There is an average of two to four eggs per clutch in the tropics, while in other regions, a clutch may contain up to nine eggs.
Social life
The level of sociability differs as expected in such a large family, with some species being highly territorial and others very social. Jackdaws, for example, have a defined hierarchy. Because of this hierarchy, clashes between individuals, which would only be to the detriment of the individual itself, are avoided.
At the same time, it also permits far greater tolerance than is found in other families of birds. If a female of low ranks mates with one of the leaders of the community, she acquires a higher rank and may command respect from other birds. Furthermore, birds that respect the social order receive aid from the community, such as when hurt.
Song
Although many species have no true song, and the call is somewhat crude, the vocal language of crows is advanced. Although there are no real differences in voice between the sexes, there are often subtle differences between individuals.
Another striking feature, even if not true for all members of the family, is their ability to mimic not only birds but other sounds such as the human voice.
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Food
The adaptability and versatility of crows show in their diets and feeding behaviour. Most species eat animals and plants and are quick to find new food sources.
They will feed on mammals, amphibians, reptiles, carrion and eggs. Insects, grains, nuts, fruit, molluscs, and worms make up their diet.
The manipulation of food is made easier by the sturdy bill widespread in the family and in most species also by the use of the feet to hold food while it is dismembered. Many species have been recorded dunking or washing food, and this may be an adaptation to counter stickiness.
Nesting/Breeding
Studies have shown that individuals do not start to breed until they are two years old, although the carrion crow and magpie may pair off and hold a territory during their second year. The delay of sexual maturity may allow young birds to gain additional experience before attempting to breed.
Members of the crow family defend exclusive breeding territories in which they nest. The raven, jay and blue jay all defend territories and are defended by the male and female. A few species nest in colonies, including the jackdaw, which has loosely spaced colonies nesting in holes. The rook nests in denser colonies in the tops of trees. Colonial nesters are gregarious throughout the year, and many of the species that hold breeding territories flock outside the breeding season, some of them occupying large communal roosts.
Territories are often occupied by the same birds year after year, and the pair often lasts for life.
Several different species of crows are known to have breeding seasons timed to take advantage of the abundant food supplies for the nestlings. In England, the rook lays its eggs in March to take advantage of the number of earthworms in April. The jay lays in late April or May to ensure there are plenty of caterpillars on trees for their young to eat.
Incubation is carried out by the female in most species, except nutcrackers, although the female is usually fed on the nest by the male. Because incubation often starts when the first egg of the clutch is laid, the nestlings differ in size as they hatch over a period of several days. When food is short, the smallest of the brood often dies.
Both parents feed the young on food that is mostly carried to the nest concealed in the throat of the adult. The fledglings are fed by their parents for a few weeks after they leave the nest. The fledglings may remain in their parent’s territory for many months after they become independent. The Florida scrub-jay stays for up to a year.
Recoveries of ringed birds of several crow species show that half of the young birds may die in the first year and that few adults live to be older than ten years.
Intelligence
The quick-wittedness and great adaptability of many of the crows may partly account for their wide distribution over four continents. Their intelligence accounts for the versatility in feeding that has allowed them to survive in harsh environments such as deserts, tundra, and cities.
Studies with ravens have seen them count up to five or six. This species and the jackdaw performed better than parrots, pigeons, and chickens in simple experiments designed to test intelligence.
Wild crows appear to use their intelligence to good effect in obtaining food. Carrion crows often drop freshwater mussels from the air onto land surfaces to break them open and obtain the animal within.
A gamekeeper who had been checking on the location of pheasant nests with clutches of eggs noted that on returning to several of the pheasant nests, he found that they had all been robbed by crows. Later observations showed that a carrion crow has learnt to watch the gamekeeper to obtain information on the location of the nests.
Birdwatchers have often been detrimental to birds of prey. While birds of prey have been disturbed from their nests by birders, ravens, carrion crows, and jackdaws have been known to rob their nests.
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Genus
Taxonomists have made various attempts to separate the whole group into sub-families. The nearest relatives of the crows are certain Australasian families such as the birds of paradise of the family Paradisaeidae, the Old World Orioles or Oroilidae, and the drongos or Dicruridea.
Crows, ravens, jackdaws, rook
The most widespread and familiar group comprises the typical crows of the genus Corvus. Crows, rooks, ravens and jackdaws are grouped together in the genus Corvus. These are large birds with tails of short or medium length and plumage that is all-black, black and white, black and grey or entirely sooty-brown.
Typical crows of the genus Corvus are absent in South America, which is the home of several species of magpies and jays. The most widespread of the Palearctic species is probably the rook which has an area of bare skin on the face at the base of the bill.
Similar, but lacking the bare skin, are the carrion and hooded crow. The two distinct races are considered of a single species which, where their ranges overlap both in Europe and in Asia, form relatively stable hybrid populations. The largest species is, without doubt, the raven which is found in the Palearctic region and also in parts of the Nearctic region, penetrating southwards as far as Central America.
There is one species of jackdaw: the Western jackdaw, and four subspecies. They can be found across western Asia, North Africa, and Europe. They are medium-sized members of the family, measuring up to 39cm (15in). The Daurian jackdaw is part of a separate genus Coloeus.
Ravens are large members of the Corvidae family. There are nine species of raven which share their taxonomic group of Corvus with other members of the family.
Ravens are generally larger than crows, and their size, heavy head and bill, and wedge-shaped tail distinguish them from the other all-black species.
They can be found in Africa, the United States, Central America, Australia, Europe, and the Arabian peninsula.
Several ravens occur in the drier and more rugged parts of Africa. The white-necked raven has a particularly heavy bill and is marked by a white crescent on the nape. Further north, the thick-billed raven is found only in Ethiopia, where it is a familiar sight among the high plateau and gorges.
It nests on cliffs and is quite common in some coastal areas where seabirds and their eggs and young ensure an adequate supply of food. Ravens are hated by sheep farmers, although they are probably only guilty of eating the afterbirth and still-born lambs.
- Algerian jackdaw (Coloeus monedula cirtensis)
- American crows (Corvus brachyrhynchos)
- Australian raven (Corvus coronoides)
- Banggai crow (Corvus unicolor)
- Bismarck crow (Corvus insularis)
- Brown-headed crow (Corvus fuscicapillus)
- Brown-necked raven (Corvus ruficollis)
- Bougainville crow (Corvus meeki)Cape crow (Corvus capensis
- Chihuahuan raven (Corvus cryptoleucus)
- Collared crow (Corvus torquatus)
- Common raven (Corvus corax)
- Cuban crow (Corvus nasicus)
- Daurian jackdaw (Corvus dauuricus)
- Eastern carrion crown (Corvus corone orientalis)
- Eastern Eurasian jackdaw (Coloeus monedula soemmerringii)
- Eastern jungle crow (Corvus levaillantii)
- Fan-tailed raven (Corvus rhipidurus)
- Fish crow (Corvus ossifragus)
- Flores crow (Corvus florensis)
- Forest raven (Corvus tasmanicus)
- Grey crow (Corvus tristis)
- Hawaiian crow (Corvus hawaiiensis)
- Hooded crow (Corvus cornix)
- House crow (Corvus splendens)
- Indian jungle crow (Corvus culminatus)
- Jamaican crow (Corvus jamaicensis)
- Large-billed crow (Corvus macrorhynchos)
- Little crow (Corvus bennetti)
- Little raven (Corvus mellori)
- Long-billed crow (Corvus validus)
- Mariana crow (Corvus kubaryi)
- Mesopotamian crow (Corvus cornix capellanus)
- New Caledonian crow (Corvus moneduloides)
- Nordic jackdaw (Coloeus monedula monedula)
- Northwestern crow (Corvus brachyrhynchos caurinus)
- Palawan crow (Corvus pusillus)
- Palm crow (Corvus palmarum)
- Pied crow (Corvus albus)
- Piping crow (Corvus typicus)
- Relict raven (Corvus tasmanicus boreus)
- Rook (Corvus frugilegus)
- Sinaloa crow (Corvus sinaloae)
- Slender-billed crow (Corvus enca)
- Somali crow (Corvus edithae)
- Thick-billed raven (Corvus crassirostris)
- Tamaulipas crow (Corvus imparatus)
- Torresian crow (Corvus orru)
- Western carrion crow (Corvus corone)
- Western Eurasian jackdaw (Coloeus monedula spermologus)
- Western Jackdaw (Coloeus monedula)
- White-billed crow (Corvus woodfordi)
- White-necked crow (Corvus leucognaphalus)
- White-necked raven (Corvus albicollis)
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Jays
There are ten genera of jays with about 50 species. Jays are not a monophyletic group without a shared ancestor. They are a varied group of birds, and jays can be highly colourful, often boasting blue or green feathers.
The green jay is perhaps one of the most beautiful of American species. Typical jays are represented by the common Eurasian jay and the Eurasian black-throated jay of the Himalayas, and Lidth’s jay of the Ryukyu islands. The Canada jay is also known as the grey jay or commonly as the whiskeyjack.
Like other members of the family, they are notable hoarders and are particularly fond of hiding away acorns for the harsh winter ahead. It is thought that jays contributed greatly to the oak forests spreading northwards following the last Ice Age due to their acorn planting.
Jays are colourful, woodland birds with rounded wings and longer tails. They are widely distributed and can be found from North and South America, Europe, and north-west Africa to the Indian subcontinent and down into Southeast Asia. Jays are the only members of the family to have spread as far as South America.
There are four species of ground jay found in the semi-arid plateaus of central Asia, belonging to the genus Podoces. They are known as ground jays because of their terrestrial habits, preferring to run on the ground rather than fly. Ground jays can fly but prefer running, although they can be seen perching on trees and bushes.
Platylophus
- Crested jay (Platylophus galericulatus)
Garrulus
- Eurasian jay (Garrulus glandarius)
- Lanceolated jay (Garrulus lanceolatus)
- Lidth’s jay (Garrulus lidthi)
Ground jays – Podoces
- Biddulph’s ground jay (Podoces biddulphi)
- Grey ground jay (Podoces panderi)
- Henderson’s ground jay (Podoces hendersoni)
- Pleskee’s ground jay (Podoces pleskei)
Ptilostomus
- Piapiac (Ptilostomus afer)
Grey jays – Perisoreus
- Canada jay (Perisoreus canadensis)
- Siberian jay (Perisoreus infaustus)
- Sichuan jay (Perisoreus internigrans)
Scrub jays – Aphelocoma
- California scrub-jay (Aphelocoma californica)
- Florida scrub-jay (Aphelocoma coerulsecens)
- Island scrub-jay (Aphelocoma insularis)
- Mexican jay (Aphelocoma wollweberi)
- Transvolcanic jay (Aphelocoma ultramarina)
- Unicolored jay (Aphelocoma unicolor)
- Woodhouse’s scrub-jay (Aphelocoma woodhouseii)
Gymnorhinus
- Pinyon jay (Gymnorhinus cyanocephalus)
Cyanocitta
- Blue jay (Cyanocitta cristata)
- Steller’s jay (Cyanocitta stelleri)
Magpie-jays – Calocitta
- Black-throated magpie-jay (Calocitta colliei)
- White-throated magpie-jay (Calocitta formosa)
Cyanocorax
- Azure jay (Cyanocorax caeruleus)
- Azure-naped jay (Cyanocorax heilprini)
- Black-chested jay (Cyanocorax affinis)
- Brown jay (Cyanocorax morio)
- Bushy-crested jay (Cyanocorax melanocyaneus)
- Cayenne jay (Cyanocorax cayanus)
- Curl-crested jay (Cyanocorax cristatellus)
- Green jay (Cyanocorax ynca)
- Plush-crested jay (Cyanocorax chrysops)
- Purplish-backed jay (Cyanocorax beecheii)
- Purplish jay (Cyanocorax cyanomelas)
- San Blas jay (Cyanocorax sanblasianus)
- Tufted jay (Cyanocorax dickeyi)
- Violaceous jay (Cyanocorax violaceous)
- White-naped jay (Cyanocorax cyanopogon)
- White-tailed jay (Cyanocorax mystacalis)
- Yucatan jay (Cyanocorax yucatanius)
Cyanolyca
- Azure-hooded jay (Cyanolyca cucullata)
- Beautiful jay (Cyanolyca pulchra)
- Black-collared jay (Cyanolyca armillata)
- Black-throated jay (Cyanolyca pumilo)
- Dwarf jay (Cyanolyca nana)
- Silvery-throated jay (Cyanolyca argentigula)
- Turquoise jay (Cyanolyca turcosa)
- White-collared jay (Cyanolyca viridicyana)
- White-throated jay (Cyanolyca mirabilis)
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Magpie
The generic term magpie is used for a group of corvids typified by the magpie. Many brilliantly coloured species come from southeast Asia: for example, the yellow-billed blue magpie, the green magpie, and the azure-winged magpie. This last species is interesting in that it occurs discontinuously as two localized populations at either extreme of the Eurasian region, one population present in Spain and Portugal and the other in China and Japan. The reasons for this apparent isolation are unclear but may well be related to the climatic factors of the glacial and post-glacial eras.
The magpie also occurs in North America, as does the yellow-billed magpie. These two species are virtually identical except for the colouration of the bill.
The magpies include the familiar piebald magpie of Europe, Asia, and North America and several more brightly coloured species from southern Asia, such as the green magpie and red-billed blue magpie.
They all have short, strong bills and very long graduated tails. The dividing line between the Asian magpies and jays relies mainly on the length of the tail, but the American jays include both short-tailed and rather long-tailed forms.
Among the American jays, there is a large proportion of species of a rather small size, some of them no bigger than large thrushes, and also a large proportion with blue in the plumage.
The magpie is one of the few species that occur both in Europe and North America. Its pied plumage gives it its name, but this has been freely applied to many other species that similarly boast long tails, devoid of black and white.
The magpie is a solitary bird of woodland that builds a large, domed nest among dense vegetation.
Black and white (Holarctic) magpies – Pica
- Asir magpie (Pica asirensis)
- Black-billed magpie (Pica hudsonaia)
- Black-rumped magpie (Pica bottenensis)
- Eurasian magpie (Pica Pica)
- Korean magpie (Pica sericea)
- Maghreb magpie (Pica mauritanica)
- Yellow-billed magpie (Pica nuttalli)
Blue and green (Oriental) magpies – Urocissa
- Red-billed blue magpie (Urocissa erythrorhyncha)
- Sri Lanka blue magpie (Urocissa ornata)
- Taiwan blue magpie (Urocissa caerulea)
- Yellow-billed blue mahpie (Urocissa flavirostris)
- White-winged magpie (Urocissa whitehadi)
Cissa
- Bornean green magpie (Cissa jefferyi)
- Common green magpie (Cissa chinensis)
- Indochinese green magpie (Cissa hypoleuca)
- Javan green magpie (Cissa thalassina)
Azure-winged magpies – Cyanopica
- Azure-winged magpie (Cyanopica cyanus)
- Iberian magpie (Cyanopica cooki)
Chough
The alpine chough and red-billed chough resemble crows in their plumage which is glossy black. However, they have more slender downcurved bills coloured red or yellow. They are mainly mountain birds but also occur near rocky sea cliffs in some regions.
The two choughs are alpine birds, extending to elevations of nearly 9,000m (27,000ft) in the Himalayas, where climbers report them around their camps. They generally appear in tightly knit flocks. They are excellent fliers and soar and dive in the air, high against the steep cliffs where they nest. While the red-billed chough is found around sea cliffs as well as in mountainous areas, the alpine chough is confined to high mountain altitudes.
- Alpine chough (Pyrrhocorax graculus)
- Red-billed chough (Pyrrhocorax pyrrhocorax)
Nutcracker
Three species of nutcracker inhabit Eurasia and North America. The European nutcracker is mainly chestnut with white streaks, whereas the American Clark’s nutcracker is mainly grey. Both feed largely on seeds of nuts and rely on hidden supplies during the winter.
The nutcrackers are among the more specialized members of the Corvidae. They live in coniferous forests and are largely dependent on the seeds of pines for their existence. The boldly spotted nutcracker is replaced in western North America by the grey Clark’s nutcracker.
- Clark’s nutcracker (Nucifraga columbiana)
- Kashmir nutcracker (Nucifraga multipunctata)
- Spotted nutcracker (Nucifraga caryocatactes)
Treepies
Crypsirina
- Hooded treepie (Crypsirina cucullata)
- Racket-tailed treepie (Crypsirina temia)
Dendrocitta
- Andaman treepie (Dendrocitta bayleyi)
- Bornean treepie (Dendrocitta cinerascens)
- Collared treepie (Dendrocitta frontallis)
- Grey treepie (Dendrocitta formosae)
- Rufous treepie (Dendrocitta vagabunda)
- Sumatran treepie (Dendrocitta occipitalis)
- White-bellied treepie (Dendrocitta leucogastra)
Platysmurus
- Bornean black magpie (Platysmurus aterrimus)
- Malayan black magpie (Platysmurus leucopterus)
Temnurus
- Ratchet-tailed treepie (Temnurus temnurus)
Piapiac
The piapiac is found in western Africa and as far east as Uganda. It is smaller than a magpie, but with an equally long and graduated tail, glossy black plumage tinged brown on tail and wings and a reddish bill in juveniles, black in the adult. It is a confiding species and roams through villages, often among flocks of sheep and goats.
Ptilostomus
- Piapiac (Ptilostomus afer)
Stresemann’s bushcrow
Zavattariornis
- Stresemann’s bushcrow (Zavattariornis stresemanni)
Found in southern Ethiopia, the Stresemann’s bush-crow is a small corvid, with grey upperparts, bluish-black wings and tail, white underparts and a patch of bare blue skin around the eye. Its habits are still not well known, but anatomical observations indicate that it belongs to the family Corvidae.
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