Vulture

For other uses, see Vulture (disambiguation).
Vulture
Griffon vulture or Eurasian griffon, Gyps fulvus, an Old World vulture
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Families

Accipitridae (Aegypiinae)
Cathartidae

Griffon vulture soaring
African hooded vulture (Necrosyrtes monachus), Kruger National Park
Head of a vulture, Mellat Park, Tehran
Some members of both the Old and New World vultures have an unfeathered neck and head, shown as radiating heat in this thermographic image.

Vulture is the name given to two groups of scavenging birds of prey: the New World vultures, including the Californian and Andean condors; and the Old World vultures, including the birds that are seen scavenging on carcasses of dead animals on African plains. Research has shown that some traditional Old World vultures (including the bearded vulture) are not closely related to the others, which is why the vultures are to be subdivided into three taxa rather than two. New World vultures are found in North and South America; Old World vultures are found in Europe, Africa and Asia, meaning that between the two groups, vultures are found on every continent except Australia and Antarctica.

A particular characteristic of many vultures is a bald head, devoid of normal feathers. Although it has been historically believed to help keep the head clean when feeding, research has shown that the bare skin may play an important role in thermoregulation.[1] Vultures have been observed to hunch their bodies and tuck in their heads in the cold, and open their wings and stretch their necks in the heat.

A group of vultures is called a wake, committee, venue, kettle, or volt. The term kettle refers to vultures in flight, while committee, volt, and venue refer to vultures resting in trees. Wake is reserved for a group of vultures that are feeding.[2][3] The word Geier (taken from the German language) does not have a precise meaning in ornithology; it is occasionally used to refer to a vulture in English, as in some poetry.

Classification

Vultures are classified into two groups: Old World vultures and New World vultures.

Old World vultures

Main article: Old World vulture

The Old World vultures found in Africa, Asia, and Europe belong to the family Accipitridae, which also includes eagles, kites, buzzards, and hawks. Old World vultures find carcasses exclusively by sight.

There are 16 species, the last three of which are distinct from the others:

New World vultures

Main article: New World vulture

The New World vultures and condors found in warm and temperate areas of the Americas are not closely related to the similar Accipitridae, but belong in the family Cathartidae, which was once considered to be related to the storks. However, recent DNA evidence suggests that they should be included among the Accipitriformes, along with other birds of prey. However, they are still not closely related to the other vultures. Several species have a good sense of smell, unusual for raptors, and are able to smell dead animals from great heights, up to a mile away.

There are seven species:

Feeding

Vultures rarely attack healthy animals, but may kill the wounded or sick. When a carcass has too thick a hide for its beak to open, it waits for a larger scavenger to eat first.[4] Vast numbers have been seen upon battlefields. They gorge themselves when prey is abundant, until their crop bulges, and sit, sleepy or half torpid, to digest their food. These birds do not carry food to their young in their claws, but disgorge it from the crop.

Vultures are of great value as scavengers, especially in hot regions. Vulture stomach acid is exceptionally corrosive, allowing them to safely digest putrid carcasses infected with Botulinum toxin, hog cholera, and anthrax bacteria that would be lethal to other scavengers.[5] New World vultures often vomit when threatened or approached. Contrary to some accounts, they do not "projectile vomit" on their attacker as a deliberate defense, but it does lighten their stomach load to make take-off easier, and the vomited meal residue may distract a predator, allowing the bird to escape.[6]

New World vultures also urinate straight down their legs; the uric acid kills bacteria accumulated from walking through carcasses, and also acts as evaporative cooling.[7]

Endangered

Main article: Indian vulture crisis

Vultures in south Asia, mainly in India and Nepal, have declined dramatically since the early 1990s.[8] It has been found that this decline was caused by residues of the veterinary drug Diclofenac in animal carcasses.[9] The government of India has taken very late cognizance of this fact and has banned the drug for animals.[10] However, it may take decades for vultures to come back to their earlier population level. The same problem is also seen in Nepal where government has taken some late steps to conserve remaining vultures.

See also

References

  1. ↑ Ward, J.; McCafferty, D.J.; Houston, D.C.; Ruxton, G.D. (April 2008). "Why do vultures have bald heads? The role of postural adjustment and bare skin areas in thermoregulation". Journal of Thermal Biology 33 (3): 168–173. doi:10.1016/j.jtherbio.2008.01.002.
  2. ↑ Lipton, James (1993). An Exaltation of Larks: The Ultimate Edition (third ed.). New York: Penguin Books. p. 275. ISBN 9780140170962. OCLC 29191881.
  3. ↑ Rodrigues, Ernie J. (May 6, 2007). "Groups to Animals". Saratoga, California: West Valley College. Archived from the original on September 21, 2009. Retrieved February 15, 2013.
  4. ↑ "Fast Vulture Facts". WebVulture.com. Archived from the original on July 18, 2011. Retrieved February 15, 2013.
  5. ↑ Caryl, Jim (September 7, 2000). "Re: How come that vultures can resist dangerous toxins when feeding on carcass". MadSci Network. Retrieved February 15, 2013.
  6. ↑ "Turkey Vulture Facts". Turkey Vulture Society. Retrieved 2012-12-01.
  7. ↑ Conger, Cristen. "Why is it a bad idea to scare a vulture?". HowStuffWorks. Retrieved February 15, 2013.
  8. ↑ Prakash, V.; Pain, D.J.; Cunningham, Arthur A.; Donald, P.F.; Prakash, N.; Verma, A.; Gargi, R.; S. Sivakumar, S. and Rahmani, A.R.; ‘Catastrophic collapse of Indian white-backed Gyps bengalensis and long-billed Gyps indicus vulture populations’; Biological Conservation, 109 (2003), pp. 381-390
  9. ↑ Oaks, J. Lindsay; Gilbert, Martin; Virani, Munir Z.; Watson, Richard T.; Meteyer, Carol U.; Rideout, Bruce A.; Shivaprasad, H. L.; Ahmed, Shakeel; Chaudhry, Muhammad Jamshed Iqbal; Arshad, Muhammad; Mahmood, Shahid; Ali, Ahmad; Khan, Aleem Ahmed (February 12, 2004). "Diclofenac residues as the cause of vulture population decline in Pakistan". Nature 427 (6975): 630–633. doi:10.1038/nature02317. PMID 14745453.
  10. ↑ Prakash, Vibhu; Bishwakarma, Mohan Chandra; Chaudhary, Anand; Cuthbert, Richard; Dave, Ruchi; Kulkarni, Mandar; Kumar, Sashi; Paudel, Khadananda; Ranade, Sachin; Shringarpure, Rohan; Green, Rhys E. (November 7, 2012). "The Population Decline of Gyps Vultures in India and Nepal Has Slowed since Veterinary Use of Diclofenac was Banned". PLOS ONE 7 (11). doi:10.1371/journal.pone.0049118. Retrieved February 15, 2013.
  • Hilty, Steven L. (2003). Birds of Venezuela. London: Christopher Helm Publishers. ISBN 9780713664188. OCLC 51031554. 

External links

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