Yellow-billed chough
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.
The Alpine chough is a unique member of the crow family that may nest at a higher altitude than any other bird. The males and the females of this species are identical in appearance although the male averages slightly larger than the female. Young birds are duller than adults with a dull yellow bill and brownish legs. The flight of Alpine choughs is swift and acrobatic with loose deep wing beats. Their high maneuverability is accomplished by fanning the tail, folding their wings, and soaring in the updraughts at cliff faces.
Alpine choughs breed 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. These birds are resident throughout their range only performing local altitudinal movements, although Moroccan birds have established a small colony near Málaga in southern Spain, and wanderers have reached Czechoslovakia, Gibraltar, Hungary, and Cyprus. Alpine choughs usually nest in cavities and fissures on inaccessible rock faces and may use holes between rocks in fields. They forage 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.
Alpine choughs are social birds that always forage in groups; these groups are larger in winter than in summer and have a constant composition in each season. Where food resources are restricted, adults dominate young birds, and males outrank females. Foraging areas change altitudinally through the year, depending on climatic factors, food availability, and food quality. During the breeding season, birds remain above the tree line, although they may use food provided by tourists at refuges and picnic areas. The movement to lower levels begins after the first snowfall. Alpine choughs feed by the day mainly in or near valley bottoms when the snow cover deepens and then return to the mountains to roost. In March and April, they frequent villages at valley tops or forage in snow-free patches prior to their return to the high meadows. Such feeding trips may cover 20 km (12 mi) distance and 1,600 m (5,200 ft) in altitude. The common call of Alpine choughs is the rippling ‘preep’ and whistled ‘sweeeooo’. They also have a rolling ‘churr’ alarm call, and a variety of quiet warbles and squeaks given by resting or feeding birds.
Alpine choughs are omnivores. During summer, they eat mainly invertebrates collected from pasture, such as beetles, snails, grasshoppers, caterpillars, and fly larvae. The diet in autumn, winter, and early spring becomes mainly fruit, including berries, rose hips, and domesticated crops such as apples, grapes, and pears where available. Alpine choughs may also eat flowers, including the pistils, perhaps as a source of carotenoids, and will readily supplement their winter diet with food provided by tourist activities in mountain regions, including ski resorts, refuse dumps, and picnic areas.
Alpine choughs are monogamous, showing high partner fidelity in summer, winter, and year to year. Pairs begin to nest in early May. Their nests are bulky and composed of roots, sticks, and plant stems lined with grass, fine twiglets, or hair. The nests may be constructed on ledges, in a cave or similar fissure in a cliff face, or in an abandoned building. The clutch is 3-5 glossy whitish eggs, which are tinged with buff, cream, or light green and marked with small brown blotches; the female incubates them for 14-21 days before hatching. The chicks hatch with a dense covering of natal down and fledge in a further 29-31 days from hatching. They are fed by both parents, and may also be fed by other adults when they have fledged and joined the flock.
Alpine choughs are not threatened at present, however, these birds can be locally threatened by the accumulation of pesticides and heavy metals in the mountain soils, heavy rain, shooting, and other human disturbances. A longer-term threat comes from global warming, which would cause the species' preferred Alpine climate zone to shift to higher, more restricted areas, or locally to disappear entirely.
According to IUCN Red List, the total population size of the Alpine chough is 1,075,000-2,535,000 mature individuals. In Europe, the breeding consists of 108,000-253,000 pairs, which equates to 215,000-507,000 mature individuals. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today are stable.
