Bearded vulture

"Ossifrage" redirects here. For the ship, see SS Ossifrage.
Bearded vulture
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Accipitriformes
Family: Accipitridae
Subfamily: Gypaetinae
Genus: Gypaetus
Storr, 1784
Species: G. barbatus
Binomial name
Gypaetus barbatus
(Linnaeus, 1758)
Distribution of Gypaetus barbatus

The bearded vulture (Gypaetus barbatus), also known as the lammergeier[lower-alpha 1] or ossifrage, is a bird of prey and the only member of the genus Gypaetus. Traditionally considered an Old World vulture, it actually forms a minor lineage of Accipitridae together with the Egyptian vulture (Neophron percnopterus), its closest living relative. It is not much more closely related to the Old World vultures proper than to, for example, hawks, and differs from the former by its feathered neck. Although dissimilar, the Egyptian and bearded vulture each have a lozenge-shaped tail — unusual among birds of prey. In July 2014, the IUCN Red List has reassesed this species to be near threatened. Before July 2014, it was actually classed as Least Concern. Their population trend is decreasing.

The bearded vulture is the only known animal whose diet is almost exclusively bone (70-90%)[2] and lives and breeds on crags in high mountains in southern Europe, the Caucasus,[3][4][5] Africa,[6] the Indian subcontinent, and Tibet, laying one or two eggs in mid-winter that hatch at the beginning of spring. Populations are resident.

Distribution and habitat

The bearded vulture is sparsely distributed across a considerable range. It may be found in mountainous regions from Europe through much of Asia and Africa. In Eurasia, it is found in the Pyrenees, the Alps, the Caucasus region, the Zagros Mountains, the Alborzs, the Altai Mountains, the Himalayas, Ladakh in north India, western and central China, Israel (although the bird has been declared extinct in Israel for the past few decades, unconfirmed sightings have been reported in 2000 as well as 2004) and the Arabian Peninsula. In Africa, it is found in the Atlas Mountains, the Ethiopian Highlands and down from Sudan to northeastern Democratic Republic of the Congo, central Kenya and northern Tanzania. An isolated population inhabits the Drakensberg of South Africa.[7]

This species is almost entirely associated with mountains and inselbergs with plentiful cliffs, crags, precipices, canyons and gorges. They are often found near alpine pastures and meadows, montane grassland and heath, steep-sided, rocky wadis, high steppe and are occasional around forests. They seem to prefer desolate, lightly-populated areas where predators who provide many bones, such as wolves and golden eagles, have healthy populations. In Ethiopia, they are now common at refuse tips on the outskirts of small villages and towns. Although they occasionally descend to 300–600 m (980–1,970 ft), bearded vultures are rare below an elevation of 1,000 m (3,300 ft) and normally reside above 2,000 m (6,600 ft) in some parts of their range. They are typically found around or above the tree line which are often near the tops of the mountains, at up to 2,000 m (6,600 ft) in Europe, 4,500 m (14,800 ft) in Africa and 5,000 m (16,000 ft) in central Asia. They even have been observed living at altitudes of 7,500 m (24,600 ft) on Mount Everest and been observed flying at a height of 24,000 ft (7,300 m).[3][4][5][7][8]

Description

A Lammergeier in Puga valley in east of Ladakh.

This bird is 94–125 cm (37–49 in) long with a wingspan of 2.31–2.83 m (7.6–9.3 ft).[7] It weighs 4.5–7.8 kg (9.9–17.2 lb), with the nominate race averaging 6.21 kg (13.7 lb) and G. b. meridionalis of Africa averaging 5.7 kg (13 lb).[7] In Eurasia, vultures found around the Himalayas tend to be slightly larger than those from other mountain ranges.[7] Females are slightly larger than males.[7][9] It is essentially unmistakable with other vultures or indeed other birds in flight due to its long, narrow wings, with the wing chord measuring 71.5–91 cm (28.1–35.8 in), and long, wedge-shaped tail, which measures 42.7–52 cm (16.8–20.5 in) in length. The tarsus is relatively small for the bird's size, at 8.8–10 cm (3.5–3.9 in). The proportions of the species have been compared to a falcon, scaled to an enormous size.[7]

Unlike most vultures, the bearded vulture does not have a bald head. This species is relatively small headed, although its neck is powerful and thick. It has a generally elongated, slender shape, sometimes appearing bulkier due to the often hunched back of these birds. The gait on the ground is waddling and the feet are large and powerful. The adult is mostly dark gray, rusty and whitish in color. It is grey-blue to grey-black above. The creamy-coloured forehead contrasts against a black band across the eyes and lores and bristles under the chin, which form a black beard that give the species its English name. Bearded vultures are variably orange or rust on their head, breast and leg feathers but this is actually cosmetic. This colouration may come from dust-bathing, rubbing mud on its body or from drinking in mineral-rich waters. The tail feathers and wings are gray. The juvenile bird is dark black-brown over most of the body, with a buff-brown breast and takes five years to reach full maturity. The bearded vulture is silent, apart from shrill whistles in their breeding displays and a falcon-like cheek-acheek call made around the nest.[7]

Behavior

Boy with live bearded vulture, Kabul

Like other vultures it is a scavenger, feeding mostly on the remains of dead animals. It usually disdains the actual meat, however, and lives on a diet that is typically 85–90% bone marrow. This is the only living bird species that specializes in feeding on marrow.[7] The bearded vulture can swallow whole or bite through brittle bones up to the size of a lamb's femur[10] and its powerful digestive system quickly dissolves even large pieces. The bearded vulture has learned to crack bones too large to be swallowed by carrying them in flight to a height of 50–150 m (160–490 ft) above the ground and then dropping them onto rocks below, which smashes them into smaller pieces and exposes the nutritious marrow.[7] They can fly with bones up to 10 cm (3.9 in) in diameter and weighing over 4 kg (8.8 lb), or nearly equal to their own weight.[7] After dropping the large bones, the bearded vulture spirals or glides down to inspect them and may repeat the act if the bone is not sufficiently cracked.[7] This learned skill requires extensive practice by immature birds and takes up to seven years to master.[11] Its old name of ossifrage ("bone breaker") relates to this habit. More seldom, these birds have been observed to try to break bones (usually of a medium size) by hammering them with their bill directly into rocks while perched.[7] During the breeding season they feed mainly on carrion. They prefer limbs of sheep and other small mammals and they carry the food to the nest unlike other vultures which feed their young by regurgitation.[12]

Live prey is sometimes attacked by the bearded vulture, with perhaps greater regularity than any other vulture.[7] Among these, tortoises seem to be especially favored depending on their local abundance. Tortoises preyed on may be nearly as heavy as the preying vulture. When killing tortoise, bearded vultures also fly to some height and drop them to crack open the bulky reptiles' hard shells. Golden eagles have been observed to kill tortoises in the same way.[7] Other live animals, up to nearly their own size, have been observed to be predaceously seized and dropped in flight. Among these are rock hyraxes, hares, marmots and, in one case, a 62 cm (24 in) long monitor lizard.[7][10] Larger animals have been known to be attacked by bearded vultures, including ibex, Capra goats, Chamois and Steenbok.[7] These animals have been killed by being surprised by the large birds and battered with wings until they fall off precipitous rocky edges to their deaths; although in some cases these may be accidental killings when both the vulture and the mammal surprise each other.[7] Many large animals killed by bearded vultures are unsteady young, or have appeared sickly or obviously injured.[7] Humans have been anecdotally reported to have been killed in the same way. However, this is unconfirmed and, if it does happen, most biologists who have studied the birds generally agreed it would be accidental on the part of the vulture.[7] Occasionally smaller ground-dwelling birds, such as partridges and pigeons, have been reported eaten, possibly either as fresh carrion (which is usually ignored by these birds) or killed with beating wings by the vulture.[7] While foraging for bones or live prey while in flight, bearded vultures fly fairly low over the rocky ground, staying around 2 to 4 m (6.6 to 13.1 ft) high.[7] Occasionally, breeding pairs may forage and hunt together.[7] In the Ethiopian Highlands, bearded vultures have adapted to living largely off human refuse.[7]

Physiology

The acid concentration of the bearded vulture stomach has been estimated to be of pH about 1 and large bones will be digested in about 24 hours, aided by slow mixing/churning of the stomach content. The high fat content of bone marrow makes the net energy value of bone almost as good as that of muscle, even if bone is less completely digested. A skeleton left on a mountain will dehydrate and become protected from bacterial degradation and the bearded vulture can return to consume the remainder of a carcass even months after the soft parts have been consumed by other animals, larvae and bacteria.[13]

Life history

The bearded vulture occupies an enormous territory year-around. It may forage over two square kilometers each day. The breeding period is variable, being December through September in Eurasia, November to June in the Indian subcontinent, October to May in Ethiopia, throughout the year in eastern Africa and May to January in southern Africa.[7] Although generally solitary, the bond between a breeding pair is often considerably close. In a few cases, polyandry has been recorded in the species.[7] The territorial and breeding display between bearded vultures is often spectacular, involving the showing of talons, tumbling and spiralling while in solo flight. The large birds also regularly lock feet with each other and fall some distance through the sky with each other.[7] The nest is a massive pile of sticks, that goes from around 1 m (3.3 ft) across and 69 cm (27 in) deep when first constructed up to 2.5 m (8.2 ft) across and 1 m (3.3 ft) deep, with a covering of various animal matter from food, after repeated uses. The female usually lay a clutch of 1 to 2 eggs, though 3 have been recorded on rare occasions.[7] which are incubated for 53 to 60 days. After hatching the young spend 100 to 130 days in the nest before fledging. The young may be dependent on the parents for up to 2 years, forcing the parents to nest in alternate years on a regular basis.[7] Typically, the bearded vulture nests in caves and on ledges and rock outcrops or caves on steep rock walls, so are very difficult for nest-predating mammals to access.[10] Wild bearded vultures have a mean lifespan of 21.4 years,[14] but have been observed to live for up to at least 45 years in captivity.[15]

Conservation status

Bearded vulture on the rocks in Gran Paradiso National Park.

The bearded vulture is locally threatened. It naturally occurs at low densities, with anywhere from a dozen to 500 pairs now being found in each mountain range in Eurasia where the species breeds. The species is most common in Ethiopia, where an estimated 1,400 to 2,200 are believed to breed.[7] Relatively large, healthy numbers seem to occur in some parts of the Himalayas as well. It was largely wiped out in Europe by the beginning of the 20th century, but has been locally reintroduced and is beginning to re-establish itself in protected areas. The bearded vulture has been successfully reintroduced to the Pyrenees of Spain (spreading into Portugal), and the Swiss and Italian Alps (with both populations spreading into France).[7] They have also declined somewhat in parts of Asia and Africa, though less severely than in Europe.[7] Declines today are usually due to poisons left out for carnivores, habitat degradation, the disturbances of nests, reduced food supplies and collisions with power lines.[7] It was formerly persecuted in significant numbers because people feared (without justification) that it regularly carried off children and domestic animals; the bird was also hunted as a trophy.[16] Despite the declines, the species clearly occupies a large range and, as such, it is listed as Near threatened on the IUCN Red List since the 24th of July 2014 .[1] Probably fewer than 10,000 pairs exist in the wild worldwide.[7]

Etymology

This species was first described by Linnaeus in his Systema naturae in 1758 as Vultur barbatus.[17] The present scientific name means "bearded vulture-eagle".

The name lammergeyer originates from German Lämmergeier, which means "lamb-vulture" or "lamb-hawk". The name stems from the belief that it attacked lambs.[18]

In culture

Bearded vulture is considered a threatened species in Iran. Iranian mythology considers the rare bearded vulture (Persian: هما, 'Homa') the symbol of luck and happiness. It was believed that if the shadow of a Homa fell on one, he would rise to sovereignty[19] and anyone shooting the bird would die in forty days. The habit of eating bones and apparently not killing living animals was noted by Sa'di in Gulistan published in 1258 and Emperor Jahangir had the crop examined in 1625 to find that it was filled with bones.[20]

The ancient Greeks used Augurs to guide their political decisions. Ossifragae were one of the few species of birds that could yield valid signs to these soothsayers.

The Greek playwright Aeschylus was said to have been killed in 456 or 455 BC by a tortoise dropped by an eagle who mistook his bald head for a stone – if this incident did occur, the bearded vulture is a likely candidate for the "eagle".

In the Bible/Torah, the bearded vulture, as the ossifrage, is among the birds forbidden to be eaten (Leviticus 11:13).

More recently, in 1945, it is said that Shimon Peres (called Shimon Persky at the time) and David Ben-Gurion found a nest of bearded vultures in the Negev desert. The bird is called peres in Hebrew, and Shimon Persky liked it so much he adopted it as his surname.[21]

References

  1. ↑ Alternative spelling: lammergeyer.
  1. 1 2 BirdLife International (2013). "Gypaetus barbatus". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
  2. ↑ http://wwf.panda.org/about_our_earth/species/profiles/birds/bearded_vulture/
  3. 1 2 Gavashelishvili, A.; McGrady, M. J. (2006). "Breeding site selection by bearded vulture (Gypaetus barbatus) and Eurasian griffon (Gyps fulvus) in the Caucasus". Animal Conservation. 9 (2): 159–170. doi:10.1111/j.1469-1795.2005.00017.x.
  4. 1 2 Gavashelishvili, A.; McGrady, M. J. (2006). "Geographic information system-based modelling of vulture response to carcass appearance in the Caucasus". Journal of Zoology. 269 (3): 365–372. doi:10.1111/j.1469-7998.2006.00062.x.
  5. 1 2 Gavashelishvili, A.; McGrady, M. J. (2007). "Radio-satellite telemetry of a territorial Bearded Vulture Gypaetus barbatus in the Caucasus". Vulture News. 56: 4–13.
  6. ↑ Krüger, Sonja (2010-04-19). "Conservation of the Bearded Vulture Gypaetus barbatus meridionalis". Africanraptors.org. Retrieved 2012-08-08.
  7. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 Ferguson-Lees, James; Christie, David A. (2001). Raptors of the World. Illustrated by Kim Franklin, David Mead, and Philip Burton. Houghton Mifflin. p. 417. ISBN 978-0-618-12762-7. Retrieved 2011-05-29.
  8. ↑ Bruce, Charles Granville (1923). The assault on Mount Everest 1922. London: Longmans, Green and Co.
  9. ↑ Beaman, Mark; Madge, Steve (1999). The Handbook of Bird Identification for Europe and the Western Palearctic. Princeton University Press. ISBN 978-0-691-02726-5.
  10. 1 2 3 "Lammergeier Vulture". The Living Edens — Bhutan. PBS. Retrieved 2011-05-30.
  11. ↑ "Lammergeier (video, facts and news)". Wildlife Finder. BBC. Retrieved 2011-05-29.
  12. ↑ Margalida, Antoni; Bertra, Joan; Heredia, Rafael (2009). "Diet and food preferences of the endangered Bearded Vulture Gypaetus barbatus: a basis for their conservation". Ibis. 151: 235–243.
  13. ↑ Houston, D.C.; Copsey, J.A. (1994). "Bone Digestion and Intestinal Morphology of the Bearded Vulture" (PDF). J. Raptor Res. Raptor Research Foundation. 28 (2): 73–78. Retrieved 2011-07-24.
  14. ↑ Brown, C.J. (March 1997). "Population dynamics of the bearded vulture Gypaetus barbatus in southern Africa". African Journal of Ecology. 35 (1): 53–63. doi:10.1111/j.1365-2028.1997.048-89048.x.
  15. ↑ Antor, R.J. (2007). "First breeding age in captive and wild Bearded Vultures Gypaetus barbatus". Acta Ornithologica. 42 (1): 114–118. doi:10.3161/068.042.0106.
  16. ↑ "Lammergeier". howstuffworks.com. Discovery Communications. 2008-04-22. Archived from the original on 12 July 2011. Retrieved 2011-05-29.
  17. ↑ Linnaeus, Carolus (1758). Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata (in Latin). Holmiae. (Laurentii Salvii). p. 87. V. albidus, dorso fusco, jugulo barbato, rostro incarnato, capite linea nigra cincto.
  18. ↑ Everett, Mike (2008). "Lammergeiers and lambs". British Birds. 101 (4): 215.
  19. ↑ Pollard, J.R.T. (1947). "The Lammergeyer: Comparative Descriptions in Aristotle and Pliny". Greece & Rome. 16 (46): 23–28. doi:10.1017/s0017383500009311. ISSN 1477-4550.
  20. ↑ Phillot, D.C. (1906). "Note on the Huma or Lammergeyer". Journal of the Asiatic Society of Bengal. 2 (10): 532–533.
  21. ↑ Marche, Stephen (2008-06-13). "Flight of Fancy". The New Republic. Retrieved 2011-05-31.

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