Chocard à bec jaune

Identification

The adult of the nominate subspecies of the Alpine chough has glossy black plumage, a short yellow bill, dark brown irises, and red legs. It is slightly smaller than the red-billed chough, at 37–39 centimetres (15–15 inches) 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. It has a similar buoyant and easy flight. 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. 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.<p>The subspecies P. g. digitatus averages slightly larger than the nominate form, weighing 191–244 g (6.7–8.6 oz) against 188–252 g (6.6–8.9 oz) for P. g. graculus, and it has stronger feet. 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, are longer in warmer areas, in line with Allen's rule. Temperature seems to be the most important cause of body variation in the Alpine chough.<p>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 the red-billed chough by its less rectangular wings, and longer, less square-ended tail.<p>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. 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.

Taxonomie

The Alpine chough was first described as Corvus graculus by Linnaeus in the Systema Naturae in 1766. It was moved to its current genus, Pyrrhocorax, by English ornithologist Marmaduke Tunstall in his 1771 Ornithologia Britannica, along with the only other member of the genus, the red-billed chough, P. pyrrhocorax. The closest relatives of the choughs were formerly thought to be the typical crows, Corvus, especially the jackdaws in the subgenus Coloeus, 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.<p>The genus name is derived from Greek πύρρος (purrhos), "flame-coloured", and κόραξ (korax), "raven". The species epithet graculus is Latin for a jackdaw. The current binomial name of the Alpine chough was formerly sometimes applied to the red-billed chough. 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.<p>The Alpine chough has two extant subspecies.<p>Moravian palaeontologist Ferdinand Stoliczka separated the Himalayan population as a third subspecies, P. g. forsythi, but this has not been widely accepted and is usually treated as synonymous with digitatus. A Pleistocene form from Europe was similar to the extant subspecies, and is sometimes categorised as P. g. vetus.<p>The Australian white-winged chough, Corcorax melanorhamphos, despite its similar bill shape and black plumage, is only distantly related to the true choughs.

Nom scientifique

Pyrrhocorax graculus

Autorité

(Linnaeus, 1766)

Ordre

Passériformes

Famille

Corvidés

Genre

Pyrrhocorax

Répartition et 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.<p>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 (11,500–16,400 ft) in the Himalayas. It has nested at 6,500 m (21,300 ft), higher than any other bird species, surpassing even the red-billed chough, which has a diet less well adapted to the highest altitudes. It has been observed following mountaineers ascending Mount Everest at an altitude of 8,200 m (26,900 ft). It usually nests in cavities and fissures on inaccessible rock faces, although locally it will use holes between rocks in fields, 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. Its penchant for waiting by hotel windows for food is popular with tourists, but less so with hotel owners.

Migration

Espèce sédentaire

Comportement

Mode de migration: Espèce sédentaire.

Conservation

Tendance de la population: stable.

Tendance de la population

stable