Alpine chough

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Alpine chough
Alpine chough (Pyrrhocorax graculus) above the pulpit in Switzerland

Alpine chough ( Pyrrhocorax graculus ) above the pulpit in Switzerland

Systematics
Order : Passerines (Passeriformes)
Subordination : Songbirds (passeri)
Superfamily : Corvoidea
Family : Corvids (Corvidae)
Genre : Mountain Crows ( Pyrrhocorax )
Type : Alpine chough
Scientific name
Pyrrhocorax graculus
( Linnaeus , 1766)

The Alpendohle ( Pyrrhocorax graculus ) is a bird art from the family of corvids (Corvidae). The 34 to 38 cm tall bird is a medium-sized member of its family and is characterized by black plumage, red legs and a yellow beak. In the field, the species can also be recognized by its acrobatic soaring flight and its whistling calls. Its patchy range includes the high mountains of the southern Palearctic , where it inhabits montane high altitudes with exposed rocks. The animals' diet consists largely of berries and invertebrates , but on occasion they also eat small vertebrates, bird eggs or human waste. Alpine choughs are very sociable, they move in swarms and occasionally breed in colonies. They build their nests in rock niches between April and June.

The Alpine chough was first described as Corvus graculus by Carl von Linné in 1766 and placed in the genus of mountain crows ( Pyrrhocorax ) by Marmaduke Tunstall . Together with its sister species , the Chough ( Pyrrhocorax pyrrhocorax ), it forms an early development line of corvids that is closely related to South Asian magpies. The species is divided into two to three subspecies, the delimitation of which is not clear. With an estimated six to seven-digit number of animals, the global population of the Alpine chough is considered stable and not endangered.

features

Build and color

Alpine chough sitting on a railing
Alpine chough on a seat guard. The species has proportionally shorter legs and a smaller head than the closely related Chough ( P. pyrrhocorax ); their tail, however, is relatively long.

The Alpendohle located with 34-38 cm of length, a span of 75-85 cm and a weight of 160-277 g in the middle of adult crows . They are characterized by a curved beak, which is significantly shorter and narrower than that of the Alpine crow ( P. pyrrhocorax ). Its base is covered with a short, dense tuft of nasal bristles . The legs and toes of the species are strong and, as is typical of mountain crows , splinted instead of paneled. They are proportionally shorter than those of the Chough. There is a clear sexual dimorphism between males and females : males are on average larger and heavier than females, but both sexes overlap in terms of their dimensions. Adult males weigh 188–280 g and reach a wing length of 270–284 mm. Their tail measures 161–179 mm, their barrel bone 45–49 mm. The male beak measures between 33 and 37 mm from the tip to the skull. In contrast, the wing length of adult females is only 251–267 mm, their weight 160–265 g. The tail of female Alpine choughs is 157–165 mm long, their beak 32–36 mm. The run of females measures 43-47 mm. It is believed that the average size of Alpine choughs increases from west to east. However, measurements paint a differentiated picture here. Chinese alpine choughs, for example, are on average larger than European ones, but have shorter legs and beaks.

Portrait of an alpine chough
Head study of an alpine chough. The birds are characterized by a relatively slender beak and very short nasal bristles .

The plumage of the species is uniformly black and, unlike that of the Alpine crow, shows only a weak sheen. It is particularly evident on the head as a bluish shimmer of metal, the contour feathers and the small arm covers . The rest of the plumage is rather matte black. The longer the feathers are exposed to the sun, the paler they become. Towards the end of the breeding season, shortly before the moult , the gray feather bases of the mantle often shine through on the breast, belly and mantle. The birds then look rather dark, slate gray. The color of the legs varies between light and orange-red, occasionally they are also deep red or light yellow. The beak of adult individuals is yellow on the outside and black on the inside. Their irises are dark brown or dark gray-brown. Males and females cannot be distinguished in terms of color. Juvenile Alpine choughs are distinguished from adult birds by their pink throats, their rather horn-colored beak and initially blackish, slightly paneled legs. In addition, their plumage is duller, lighter and looser than that of adult individuals and their irises are lighter brown.

Flight image and locomotion

Alpine choughs in flight on the Bürglen, 2165 m above sea level. M., Switzerland, Bernese Oberland

Alpine choughs spend a large part of the day fielding on the ground or sailing in the air. On the ground, the birds move about by hopping, striding or running. In the branches of trees or bushes they also reach thin outer branches with flapping wings. They are happy to sit on high seat control rooms such as rooftops, antennas or power lines. The flight of the species is characterized by great maneuverability and skillful use of updrafts . On warm days, the birds often soar effortlessly to great heights with just a few flaps of their wings. In flight, individual animals and flocks often follow the contours of the landscape, such as slopes and steep walls, on which they slide along at a short distance. It is not uncommon for them to be observed as they tumble into the depths, only to catch themselves later. In cross-country flight, the species reaches speeds of 70-80 km / h, in direct dive flight around 200 km / h. In the evening, the animals prefer to fly to their sleeping quarters in circling soaring, taking advantage of the thermals. Only in strong winds or lack of thermals do they lapse into active cross-country flight. In the air it differs from the Chough by its rounded tail, its curved, narrower wings and the tips of the wings that are less fingered.

Vocalizations

The calls of the alpine chough are characterized by their chirping, bright character. They sound more melodious and softer than those of the Alpine crow or other raven bird species and usually consist of short syllables. Rough, croaking sounds are also used, but they are significantly less common than in the rest of the family. Studies on aviary birds differentiate between two basic vocal sounds : on the one hand griig , which is interpreted as "Come here!", And on the other hand Zijag , which is translated by the authors as "go away!" These messages can be strengthened or weakened by changing the volume and emphasis, or they can be given a completely different meaning through rapid repetition or a different pitch. No special meaning can be assigned to the “ subsong ” of the species. It can be heard mainly in spring and consists mainly of series of varying griig syllables. The vocabulary of the alpine chough is highly situation-specific and more versatile than that of the alpine rook.

distribution

Eurasia map with distribution marked in green
The recent distribution area of ​​the alpine chough stretches gaps over the high mountains of the southern Palearctic . In the Plio and Pleistocene it reached far into the mammoth steppes to the north and also included the Canary Islands .

The range of the Alpine chough today comprises a relatively narrow band that stretches across the mountains of the southern Palearctic . It has its easternmost point in the southwest of the Tibetan Plateau . From there it probably extends northwest over the entire highlands to the Takla Makan and the Lop Nor . In the south, the Himalayan mountain range forms the boundary of the Artarea. Further west it extends over the Tian Shan and its foothills as well as over the Hindu Kush . It is unclear whether these populations are connected to those in the Iranian Zāgros and Elburs ; there is probably a distribution gap between the Iranian highlands and the Hindu Kush. The distribution area of ​​the Alpine chough extends from Iran over the Caucasus and the southern mountain ranges of Asia Minor . Further south there are smaller, dispersed populations in Lebanon and on the Hermon . The European area of ​​the species includes Crete , the west of the Rhodope and the Balkan Mountains and the Dinarides . From there the distribution area extends over the entire Alps and the northern and central Apennines . In the western Mediterranean only Sardinia is populated. On the Iberian Peninsula , the deposits include the Pyrenees , the Cantabrian Mountains and the Sierra de Guadarrama . In Morocco there is an occurrence in the western Atlas .

During the Plio and Pleistocene , the Alpine chough belonged to the main species of the mammoth steppe, along with the then rarer Alpine crow . Since it found a habitat similar to that in the high mountains, it was able to penetrate far north and south. Both species were probably originally restricted to the Tibetan highlands and the Himalayas, before they first spread over the Alpid mountains in the Pliocene and, as a result of climate change in the Pleistocene, also colonized the lowlands and the islands of the Mediterranean. After the end of the cold ages, the Artareal shrank back to the Palearctic high mountains. The Alpine chough is a resident bird and remains fully grown at the nesting site all year round. Only young birds and immature animals pass between individual breeding areas in autumn.

habitat

Photo of an alpine chough on the edge of a glacier valley
Alpine chough over a glacier in the French Alps. The species is dependent on open areas as a feeding habitat and rock walls as a breeding ground, but both do not have to be in close proximity to each other.

The preferred habitat of the Alpine chough is extensive, free areas in montane and alpine surroundings. It uses mountain meadows, mown pastures or scree fields as a feeding habitat, which it often shares with the Alpine crow. The range of inaccessible rock niches that act as breeding habitats only bind the Alpine chough to a limited extent. The birds often cover several kilometers from their sleeping and breeding grounds to the feeding grounds every day and also overcome obstacles such as mountain ridges or forests. The birds also colonize grazed karst areas (e.g. on the western Balkan peninsula ). In parts of its range, especially in the Alps, the species can also be found in urban habitats, where it mainly draws rich sources of food. Snow-covered areas are largely avoided and given up in winter. The species usually stays away from forests or larger tree populations.

Basically, the Alpine chough can be found above the tree line , but occurs sporadically and especially in winter at lower altitudes. Few bird species breed at similarly high altitudes: The breeding areas in the Swiss Alps reach up to 3800 m, in the Atlas up to 3900 m. In Kashmir, the occurrences in the summer range between 3500 and 5000 m. An exception in this regard is the Balkans, where the birds breed between 500 and 1400 m in many places. Alpine choughs have been observed looking for food on Mount Everest at over 8200 m. Reports of sightings at altitudes above 9500 m also come from Everest expeditions.

Way of life

food

Alpine choughs on the railing of a mountain hiking trail
In contrast to the Chough , the Alpine chough prefer to eat human food and seek proximity to settlements and tourist facilities such as hiking trails
Alpine choughs on the Zugspitze

The alpine chough is omnivorous . Like the Chough, it primarily eats invertebrates and fruit, but shows greater nutritional opportunism and is also more willing to eat other types of food. Arthropods and their larvae, snails and earthworms dominate the food spectrum of the species in spring and summer, while stone fruits , berries and pome fruit gain in importance towards autumn , provided they exist in sufficient quantities. Even then, locusts that appear in large numbers make up a large part of the diet. In winter, berries and conifer seeds usually form the food base of the Alpine chough. Wherever it ends up with human waste, it becomes the main source of food in winter. In addition, the Alpine chough also eats bird eggs, carrion or small vertebrates all year round , provided it can get hold of them. It regularly eats grit and often ingests snow in winter.

The Alpine chough takes a large part of its food in open areas with short or sparse vegetation. If possible, she avoids forests and semi-open forms of vegetation as well as tall grass and snow. Preferred foraging habitats are freshly mown meadows, mountain pastures and similar areas. There the alpine chough looks for food in groups in the fields . The bandages usually move in one direction and only comb through a small area of ​​the available area. The birds tend to pick up food superficially from stalks and from the ground. They poke less often in the upper layers of the earth than Alpine crows, for example, which is why they rarely get in each other's way when sharing their habitat. Alpine choughs search specifically for food under stones, dried dung patties or in pieces of wood and knock them over with their beak for this purpose. In addition to open areas, the outer branches of bushes and fruit trees are frequented by swarms of alpine choughs, where the birds harvest fruit intensively, only to fly off again shortly afterwards. Even in flight, they capture a considerable part of their food. The animals fly against the wind at low altitude to catch grasshoppers and other insects from the air. Especially in winter, the species is often found in mountain villages, at ski stations and in mountain stations, where it is drawn by the supply of human food residues. The alpine chough regularly hides such food in order to retrieve and eat it later. Most of the food pieces are deposited in rock crevices, between gravel or under roof tiles and are often covered with stones, lichen or pieces of wood.

Social and territorial behavior

A flock of alpine choughs on the Simplon Pass

Alpine choughs are sociable birds that usually live in larger groups all year round. Only occasionally do they move in pairs or in small family groups. Within the flocks there are both breeding partners, who can be recognized by their short individual distance, as well as unmated young birds. The size of swarms of alpine choughs fluctuates over the year. In spring it is lowest due to the absence of breeding pairs, while it reaches its maximum in late autumn and winter, when the young birds that have flown out arrive. The largest of these swarms in the Alps contain up to 1000 animals. Larger groups come together primarily when searching for food and can then come from individuals from different sleeping places.

Within the swarm, communication is primarily carried out via vocal touch sounds, body posture and waving of wings, and coherence is ensured, although cohesion is rather loose, especially when working in the fields. Couples also communicate by stroking each other. When foraging, individual individuals dominate over others. Several factors play a role for dominance, including body size, age, mating or a male gender. From time to time, Alpine choughs negotiate the priority of one animal over another in fights. These can range from beak and wing threats to violent clashes. Often the opponents are surrounded by other swarm members who shout loudly or attack the fighting in appearance. In the flying swarm there is no obvious hierarchy, at the breeding site females usually dominate over males.

Reproduction and breeding

Photo of an egg with a millimeter scale
Egg of an alpine chough, Museum Wiesbaden collection

The alpine chough mates all year round, but especially in the winter months. The courtship takes place in groups and has the swarm as the scene. It is initiated by a single bird, to which a second answers, whereupon more Alpine choughs gradually become courtiers. They let their wings hang down, spread their tails down to the ground and stretch their heads straight up. The up to 20 individuals large courtship groups finally walk stiff-legged in a closed formation. Usually the group moves up the slope to an exposed point. The courtship is characterized by numerous gestures of expression, but never turns into violence. Females are courted by males with food gifts and are both fed and guarded in fixed pairs. The couples are monogamous and usually last until one partner dies.

Alpine choughs can become sexually mature at an early age in captivity, but usually the first brood does not take place until the age of three. The breeding season begins, depending on the region, in April and extends into July in some parts of the distribution area. They are not typical rock breeders , but prefer inaccessible niches as breeding grounds, which also offer a certain protection from wind and weather. In addition to crevices and niches in the rock, human structures can also be used. At the breeding site, the birds build a spreading nest structure made of sticks, stalks and roots with a central hollow. It is lined with fine blades of grass, feathers, hair and small twigs. The clutch usually consists of three to five eggs, which the female lays every day. The young hatch after 17-21 days and then remain in the nest for around 30-40 days before they fly out. The breeding success is relatively low; Usually only one or two young fly out per brood.

Systematics and taxonomy

The Alpine chough was first described by Carl von Linné in the 12th edition of the Systema naturae as Corvus graculus in 1766 . The specific epithet graculus is an old Latin name for the jackdaw , which in Europe was not clearly distinguished from the alpine chough until the early modern period. In 1771 Marmaduke Tunstall placed them together with the Alpine crow in the newly created genus Pyrrhocorax . Both species are closely enough related to produce fertile hybrids . These hybrids have the sound inventory of both species and are morphologically intermediate forms.

The Alpine chough is classically divided into two to three recent and one extinct subspecies: P. g. graculus for the western, P. g. digitatus for the middle and P. g. forsythi for the eastern Palearctic. However, since no author has so far been able to identify clear differences, this distinction has been questioned or modified by many authors. Usually the subspecies digitatus was seen as closer to forsythi and was associated with it under the older name digitatus , with a wing length of more than 280 mm being considered diagnostic for this subspecies. In the same way, Middle Eastern birds could also be more closely related to graculus , with which the remaining eastern populations would have to be gathered under forsythi . Morphometric studies of the subspecies graculus and digitatus showed that the variation within these subspecies is greater than between them. This result casts doubt on the current separation of populations. Combined morphometric and acoustic measurements identified birds from East Asia as basal in the cluster analysis . As a sister branch, they face North African-Iberian populations and Central European Alpine choughs. The on average smaller alpine choughs of the European Pleistocene are divided into a separate Chronosubspecies P. g. vetus .

Subspecies of the Alpine chough
subspecies author Dimensions distribution annotation
P. g. digitatus Hemprich & Ehrenberg , 1833 Blades: ♀ 266–273 mm, ♂ 283–288 mm;
Tail: 165-178 mm, 174-193 mm;
Beak: ♀ 39–41 mm, ♂ 41–43 mm;
Tarsus: 39–41 mm, ♂ 49–51 mm 		Anatolia and the Middle East to the Caucasus and southwestern Iran If the birds from the type locality of Lebanon are closer to P. g. graculus should be related, the remaining populations would have to be P. g. forsythi to be slammed.
P. g. forsythi Stoliczka , 1874 Blades: ♀ 262–273 mm, ♂ 274–296 mm;
Tail: 165-178 mm, 174-193 mm;
Beak: ♀ 32–36 mm, ♂ 34–38 mm;
Tarsus: 41–46 mm, ♂ 42–48 mm;
Weight: ♀ 203–213 g, ♂ 223–244 g 		Afghanistan to East Asia Named after Thomas Douglas Forsyth . If the differences between East and West Asian birds turn out to be significantly smaller than between West Asian and European birds, this subspecies should be listed under P. g. digitatus .
P. g. graculus ( Linnaeus , 1766) Blades: ♀ 251–267 mm, ♂ 270–284 mm;
Tail: 157-165 mm, ♂ 161-179 mm;
Beak: 32–36 mm, ♂ 33–37 mm;
Tarsus: 43–47 mm, ♂ 45–49 mm;
Weight: ♀ 180–265 g, ♂ 195–265 g 		North Africa and Europe Nominate form
P. g. vetus † Kretzoi , 1962 Tarsus: 41–48 mm Europe of the Plio and Pleistocene Chronosubspecies ; " Vetus " Latin for "old", "old"

status

Alpine chough ( Pyrrhocorax graculus ) on a mountain in Austria .

No estimates or projections are available for the global population of the Alpine chough. The inventory is difficult because the occurrences fluctuate strongly with the seasons and follow the changing food supply. The stocks are only recorded more precisely for individual European countries. Around half of the European population of 48,000 to 96,000 breeding pairs can be found in the Alps. Another 10,000 breeding pairs live in Spain . The rest of the European breeding pairs are concentrated in the Balkans . The occurrences in the Middle East are hardly recorded, only the southern Turkish breeding population of around 10,000 pairs has been researched as well as the European one. The occurrences in the Caucasus and the Eastern Palearctic Mountains are considered to be relatively thin and limited to high altitudes, but are considered stable. In the last two centuries the species only disappeared locally at some breeding sites where it was already rare before, but it also partially repopulated, as in Lebanon . In Europe, neither persecution nor major changes in their habitat have led to their decline in the long term. Since the birds are coping much better with the structural change in the Alps than the Alpine crow , for example , they are not protected in any European country. BirdLife International lists the species as globally safe ( least concern ).

swell

literature

  • Salím Ali Ali, S. Dillon Riplay: Handbook of the Birds of India and Pakistan. 2nd Edition. Volume 5: Larks to the Gray Hypocolius . Oxford University Press, London 1972.
  • Hans-Günther Bauer, Einhard Bezzel , Wolfgang Fiedler : The compendium of birds in Central Europe . tape 2 : Passeriformes . Aula-Verlag, Wiebelsheim 2005, ISBN 3-89104-648-0 .
  • Stanley Cramp , Christopher M. Perrins : Handbook of the Birds of Europe, the Middle East and North Africa: The Birds of the Western Palearctic . Volume 8: Crows to Finches. Oxford University Press, Oxford 1994, ISBN 0-19-854679-3 .
  • Urs N. Glutz von Blotzheim, KM Bauer : Handbook of the birds of Central Europe . tape 13 / III: Passeriformes (4th part). Aula-Verlag Wiebelsheim, Wiesbaden 1993, ISBN 3-89104-460-7 .
  • Friedrich Wilhelm Hemprich, Christian Gottfried Ehrenberg: Symbolae Physicae seu Icones et Descriptiones corporum Naturalium Novorum aut Minus Cognitorum quae ex itineribus per Libyam Aegyptium Nubiam, Dongalam, Syriam, Arabiam et Haberssiniam publicio instituto sumptu Friderici Guilelbergmi Medicinae Ehrenchirurg et Christiani Godofredi studio annis MDCCCXX-MDCCCXXV redierunt, fol. az, aa-gg. . Berlin 1833.
  • Josep del Hoyo , Andrew Elliott, Jordi Sargatal, José Cabot: Handbook of the Birds of the World . Volume 14: Bush-shrikes to Old World Sparrows . Lynx Edicions, Barcelona 2009, ISBN 978-84-96553-50-7 .
  • Miklós Kretzoi: Bird remains from the old Pleistocene fauna of Betfia . In: Aquila . tape 62/63 , 1962, pp. 167–174 ( full text [PDF; 3.5 MB ]).
  • Paola Laiolo, Antonio Rolando: Ecogeographic Correlates of Morphometric Variation in the Red-billed Chough Pyrrhocorax pyrrhocorax and the Alpine Chough Pyrrhocorax graculus . In: Ibis . tape 143 , no. 3 , June 28, 2008, p. 602-616 , doi : 10.1111 / j.1474-919X.2001.tb04888.x .
  • Paola Laiolo, Antonio Rolando, Anne Delestrade, Augusto De Sanctis: Vocalizations and Morphology: Interpreting the Divergence among Populations of Chough Pyrrhocorax pyrrhocorax and Alpine Chough P. graculus . In: Bird Study . tape 51 , no. 3 , 2004, p. 248-255 , doi : 10.1080 / 00063650409461360 .
  • Carl von Linné: Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio duodecima, reformata . Lars Salvi, Stockholm 1766 ( (full text) ).
  • Rodolphe Meyer de Schauensee: The Birds of China . Smithsonian Institution Press, Washington, DC 1984, ISBN 0-87474-362-1 .
  • Cécile Mourer-Chauviré: Les oiseaux du Pléistocène moyen et supérieur de France. Première part . In: Documents des Laboratoires de Géologie de la Faculté des Sciences de Lyon . tape 64 , no. 1 , 1975, p. 1-264 .
  • Ferdinand Stoliczka: Letters to the Editor . In: Stray Feathers . tape 2 , no. 4 , 1874, p. 461-465 .
  • Marmaduke Tunstall: Ornithologia Britannica: seu Avium omnium Britannicarum tam terrestrium, quam aquaticarum catalogus. Sermons Latino, Anglico et Gallico redditus. . The Willughby Society, London 1771, doi : 10.5962 / bhl.title.14122 .
  • Narit Sitasuwan, Ellen Thaler: Sound inventory and communication with Alpine crow (Pyrrhocorax pyrrhocorax), Alpine chough (Pyrrhocorax graculus) and their hybrids . In: Journal of Ornithology . tape 126 , no. 2 , April 1985, pp. 181-193 , doi : 10.1007 / BF01642887 .
  • Charles Vaurie: Systematic Notes on Palearctic Birds. No. 4. The Choughs ('' Pyrrhocorax '') . In: American Museum Novitates . tape 1648 , 1954, pp. 1–7 ( full text [PDF]).

Web links

Commons : Alpine chough  - Collection of images, videos and audio files
Wiktionary: Alpendohle  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ↑ a b von Linné 1766, p. 158.
  2. ↑ a b Bauer et al. 2005, p. 49.
  3. ↑ a b c del Hoyo et al. 2009, p. 615.
  4. ↑ Laiolo et al. 2004, p. 255.
  5. ↑ a b Cramp & Perrins 1994, p. 105.
  6. ↑ Cramp & Perrins 1994, p. 104.
  7. ↑ Glutz von Blotzheim & Bauer 1993, pp. 1596–1597.
  8. ↑ Cramp & Perrins 1994, pp. 95-96.
  9. ↑ Sitasuwan & Thaler 1985, pp. 184-190.
  10. ↑ Meyer de Schauensee 1984, p. 549.
  11. ↑ Glutz von Blotzheim & Bauer 1993, pp. 1571–1573.
  12. ↑ Glutz von Blotzheim & Bauer 1993, p. 1629.
  13. ↑ Finlayson 2011, p. 41.
  14. ↑ Glutz von Blotzheim & Bauer 1993, p. 1585.
  15. ↑ Glutz von Blotzheim & Bauer 1993, p. 1589.
  16. ↑ Glutz von Blotzheim & Bauer 1993, pp. 1580–1589.
  17. ↑ David Holyoak: Behavior and Ecology of the Chough and the Alpine Chough. In: Bird Study Volume 19, Number 4, pp. 215-227. DOI: 10.1080 / 00063657209476345
  18. ↑ Glutz von Blotzheim & Bauer 1993, pp. 1612-1513.
  19. ↑ Cramp & Perrins 1994, p. 98.
  20. ↑ Glutz von Blotzheim & Bauer 1993, pp. 1598–1600.
  21. ↑ Cramp & Perrins 1994, p. 99.
  22. ↑ Glutz von Blotzheim & Bauer 1993, pp. 1602-1608.
  23. ↑ Glutz von Blotzheim & Bauer 1993, pp. 1604-1606.
  24. ↑ Glutz von Blotzheim & Bauer 1993, pp. 1590–1593.
  25. ↑ Tunstall 1771, p. 2.
  26. ↑ Glutz von Blotzheim & Bauer 1993, p. 1571.
  27. ↑ Laiolo & Rolando 2001, p. 613.
  28. ↑ Laiolo et al. 2004, pp. 252-253.
  29. ↑ Mourer-Chauviré 1975, p. 224.
  30. ↑ Hemprich & Ehrenberg 1833, sig. z.
  31. ↑ Vaurie 1954, p. 4.
  32. ↑ Stoliczka 1874, p. 462.
  33. ^ Ali & Ripley 1973, p. 238.
  34. ↑ Glutz von Blotzheim & Bauer 1993, pp. 1575–1576.
  35. ↑ Kretzoi 1962, p. 173.
  36. ↑ Mourer-Chauviré 1975, p. 225.
  37. ↑ Bauer et al. 2005, p. 50.
  38. ^ Butchart & Ekstrom 2013. Accessed February 10, 2013.