INTRODUCTION:
Numerous studies made both in the wild and in captivity, lead us to believe that Corvidae are intelligent birds, with considerably larger brain than other bird species. They are able to adapt to different environments, only by viewing the landscapes while flying, thanks to their high capacity for memory and learning. They communicate through displays including visual and acoustic signals, and their vocal repertoire is quite complex.
DESCRIPTION OF THE BIRD:
The adult has entirely black plumage with greenish gloss on head and wings, and mostly purplish-red on rest of upperparts.
The underparts are black too, with faint scaling on breast, flanks and belly, whereas the lower underparts are dull black.
In worn plumage, the bird is dull black overall.
The stout bill is black. The eyes are dark brown. Legs and feet are black.
Both sexes are similar.
The juvenile has duller, sooty black plumage. The eyes are greyer and the gape may be pale or flesh-coloured until the autumn.
The chicks have sooty grey down, but the pink skin is visible.
Several individuals with whitish patches on wings can be seen, more often in urban environment where they feed on bread and refuse, whereas in the countryside, the food is more varied and rich. Lack of vitamins could be the cause of these white areas.
SUBSPECIES AND RANGE:
The Carrion Crow has two recognized subspecies.
C.c. corone (described and displayed) occurs in Britain, France, Spain and Portugal, E to Denmark, W Germany, Czech Republic, Slovakia, Austria, N Italy and Switzerland.
C.c. orientalis breeds in eastern Asia, from C Siberia and N Mongolia to N China, and E to Japan.
This race is larger than nominate and has larger, stouter bill. The bill size varies and increases from west to east.
The Carrion Crow may hybrids with Corvus cornix, giving black birds with scattered grey feathers on mantle and breast.
HABITAT:
The Carrion Crow frequents a wide range of habitat types, from city centres to open country with scattered trees, and from wooded areas to seacoasts.
It is usually seen in parks and gardens in urban areas, in cultivated fields and pastures, forest clearings, moorland and inshore islands. Along the coast, it frequents sea cliffs and estuarine mudflats.
The nominate race “corone” can be seen from sea-level up to 2000 metres of elevation, whereas the race “orientalis” can be seen up to 3600 metres in C Asia.
BEHAVIOUR IN THE WILD:
The Carrion Crow is omnivorous and well-known for its scavenging habits. The diet includes small vertebrates, eggs and nestlings of other bird species, molluscs, frogs and some plant matter such as vegetables and grains during winter.
The food items differ according to the habitats. The Carrion Crow feeds mainly on the ground, searching for invertebrates among seaweeds or stones. It may occasionally catch birds in flight such as the Common Starling, whereas Common Wood-Pigeon or Northern Lapwing can be taken on the ground, and killed by two or three crows hunting together.
It takes shellfish on the coast, dropping them from the air onto a hard surface to break open the shells. It feeds on carrion along the roads, and forages along the water, as well lakes as sea shores, where it can find dead or live food items.
But the Carrion Crow is very opportunist and is able to get food in several different ways. It pursues sometimes other birds in flight to force them to drop or regurgitate their food.
The Carrion Crow is usually found in pairs or family groups. They may form large flocks of 50-100 individuals at abundant food sources, usually tidal mudflats and rubbish dumps. They may roost in mixed flocks in large trees during winter.
During the breeding season, the Carrion Crow performs some courtship displays such as mutual preening and rapid head-bowing display by male, while the tail is fanned. The bird moves from side to side, raising and lowering its fanned tail. Aerial displays occur all year round, with fast flight, diving and calling.
The pair is monogamous with long-term pair-bonds. Both mates are territorial and defend the territory where they nest solitary. However, they may form loose colonies in extensive feeding areas, and colonial nesting has been reported in NE Germany. Helpers have been observed in Switzerland and N Spain.
Like numerous Corvidae, the Carrion Crow often mobs birds of prey in order to drive them away from the territory.
The Carrion Crow of nominate race is mainly resident, although numerous C European birds may travel S and W in winter. They can reach Corsica, Sardinia and SE Europe.
The race “orientalis” of the northern parts of the range migrate S to E and SE China, and S to NE Iran, Baluchistan and N Pakistan in winter.
The Carrion Crow has long wings and short, rounded tail, allowing it to make long, continuous, powerful flights with active wingbeats.
REPRODUCTION OF THIS SPECIES:
The breeding season usually starts in late March with peak of egg-laying in mid-April in W Europe. The eastern race “orientalis” breeds mostly between early April and late May/early June. Both races produce a single brood per season.
Both sexes build a large nest with sticks and twigs. Some mud is added at base to strengthen the structure. Some other materials such as rabbit bones, wire and heather twigs are added too. The deep cup receives a thick lining of wool, fur, feathers, grasses and paper.
The nest is usually built in the crown of a tall tree, but depending on the location, it can be placed on pylons or coastal cliff ledges, old buildings, reedbeds, or even on the ground among heather, or protected by stone wall or rocks.
The female lays 4-5 bluish-green eggs with dark speckles. The female incubates during 19-20 days. She is fed by the male on or near the nest during at least the first 9-10 days during this period.
During the first days of their life, the chicks, covered with grey down, are fed on regurgitated food by the female. Later, both parents feed them on worms and various types of meat, and they are growing fast.
They leave the nest about 26-34 days after hatching, but they still depend on adults for several weeks more. They will breed when 15-17 months old.
PROTECTION / THREATS / STATUS:
The Carrion Crow has large range where this species is abundant and even increasing its numbers after years of persecution by farmers and hunters. This species is often considered a pest as it can eat almost anything including gamebird eggs and chicks.
Creation of large parks and gardens in urban areas provided them suitable and safe habitat.
The race “orientalis” is common over most of its wide range.
Both populations are very large, and currently, the Carrion Crow is evaluated as Least Concern.
Sources :
HANDBOOK OF THE BIRDS OF THE WORLD Vol 14 by Josep del Hoyo-Andrew Elliot-David Christie – Lynx Edicions – ISBN: 9788496553507
ENCYCLOPEDIE DES OISEAUX DE FRANCE ET D’EUROPE – de Peter Hayman et Rob Hume – Flammarion – ISBN : 2082009920
THE COMPLETE BOOK OF BRITISH BIRDS – Written by “Royal Society for the Protection of Birds” experts – Préface de Magnus Magnusson – Michael Cady- Rob Hume Editors – ISBN: 0749509112
THE HANDBOOK OF BIRD IDENTIFICATION FOR EUROPE AND THE WESTERN PALEARCTIC by Mark Beaman, Steve Madge – C. Helm – ISBN: 0713639601
BirdLife International (BirdLife International)
Pájaros de España (JL Beamonte)
Wikipedia, the free encyclopaedia
