The Alpine chough () 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 eastwards through southern Europe and North Africa to Central Asia and Nepal, 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 beak, 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. 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.
The genus name is derived from Greek , "flame-coloured", and , "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.
The Alpine chough has two extant subspecies. P. g. graculus, the nominate subspecies in Europe, north Africa, Turkey, the Caucasus and northern Iran. P. g. digitatus, described by the German naturalists Wilhelm Hemprich and Christian Gottfried Ehrenberg as P. alpinus var. digitatus in 1833, is larger and has stronger feet than the nominate race. It breeds in the rest of the depicted Asian range, mainly in the Himalayas. 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.
The Australian white-winged chough, Corcorax melanorhamphos, despite its similar bill shape and black plumage, is only distantly related to the true choughs.
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. It is slightly smaller than red-billed chough, at length with a tail and a wingspan, but has a proportionally longer tail and shorter wings than its relative. 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.
The subspecies P. g. digitatus averages slightly larger than the nominate form, weighing against 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, 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.