Gracchio corallino

Identificazione

The adult of the "nominate" subspecies of the red-billed chough, P. p. pyrrhocorax, is 39–40 centimetres (15–16 inches) in length, has a 73–90 centimetres (29–35 inches) wingspan, and weighs an average 310 grammes (10.9 oz). 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) but the juvenile has an orange bill and pink legs until its first autumn, and less glossy plumage.<p>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.<p>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. 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.

Tassonomia

The red-billed chough was first described by Carl Linnaeus in his 1758 10th edition of Systema Naturae as Upupa pyrrhocorax. It was moved to its current genus, Pyrrhocorax, by Marmaduke Tunstall in his 1771 Ornithologia Britannica. The genus name is derived from Greek πυρρός (pyrrhos), "flame-coloured", and κόραξ (korax), "raven". The only other member of the genus is the Alpine chough, Pyrrhocorax graculus. The closest relatives of the choughs are the typical crows, Corvus, especially the jackdaws in the subgenus Coloeus.<p>"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. 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.<p>There are eight extant subspecies, although differences between them are slight.<p>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.<p>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.

Nome scientifico

Pyrrhocorax pyrrhocorax

Autorità

(Linnaeus, 1758)

Ordine

Passeriformi

Famiglia

Corvidi

Genere

Pyrrhocorax

Areale e 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.<p>Its main habitat is high mountains; it is found between 2,000 and 2,500 metres (6,600 and 8,200 ft) in North Africa, and mainly between 2,400 and 3,000 metres (7,900 and 9,800 ft) in the Himalayas. In that mountain range it reaches 6,000 metres (20,000 feet) in the summer, and has been recorded at 7,950 metres (26,080 feet) altitude on Mount Everest. In the British Isles 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. It tends to breed at a lower elevation than the Alpine chough, that species having a diet better adapted to high altitudes.

Migrazione

Specie stanziale

Comportamento

Comportamento migratorio: Specie stanziale.

Conservazione

Tendenza della popolazione: in diminuzione.

Tendenza della popolazione

in diminuzione