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Black vulture

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American Black Vulture
Coragyps atratus brasiliensis in Panama
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Aves
Order:
Ciconiiformes (disputed)
Family:
Cathartidae
Genus:
Coragyps

Species:
C. atratus
Binomial name
Coragyps atratus
Subspecies
  • C. a. atratus Bechstein, 1793
    North American Black Vulture
  • C. a. foetens Lichtenstein, 1817
    Andean Black Vulture
  • C. a. brasiliensis Bonaparte, 1850
    Southern American Black Vulture
Approximate range/distribution map of the American Black Vulture. Red indicates presence.
Synonyms

Cathartidarum Winge, 1888

The American Black Vulture, Coragyps atratus, also known as the Black Vulture, is a bird in the New World vulture family which lives from the southeastern United States to South America. Although a common and widespread species, it has a somewhat more restricted distribution than its compatriot, the Turkey Vulture, which breeds well into Canada and south to Tierra del Fuego. Despite the similar name and appearance, this species is unrelated to the Eurasian Black Vulture. The latter species is an Old World vulture in the family Accipitridae (which includes eagles, hawks, kites and harriers), whereas the American species is a New World vulture. It is the only extant member of the genus Coragyps, which is in the family Cathartidae. It inhabits relatively open areas which provide scattered forests or shrublands.[1] With a wingspan of 1.5 m (5 ft) the American Black Vulture is a large bird but is relatively small for a vulture. It has black plumage, a featherless, grayish-black head and neck, and a short, hooked beak.

The American Black Vulture is a scavenger and feeds on carrion, but will also eat eggs or kill new born animals. In areas populated by humans, it also feeds at garbage dumps. It finds its meals using either its keen eyesight or by following other vultures which possess a sense of smell. Lacking a syrinx—the vocal organ of birds—its only vocalizations are grunts or low hisses.[2] It lays its eggs in caves, hollow trees, or on the bare ground and generally raises two chicks each year, which it feeds by regurgitation. In the United States of America, the vulture receives legal protection under the Migratory Bird Treaty Act of 1918.[3] This vulture also appeared in Mayan codices.

Taxonomy

The common name "vulture" is derived from the Latin word vulturus, which means "tearer" and is a reference to its feeding habits.[4] The species name, atratus, means "clothed in black,"[5] from the Latin ater 'black'.[6] The genus name, Coragyps means "raven-vulture",[7] from a contraction of the Greek corax/κοραξ and gyps/γυψ for the respective birds. The family name, Cathartidae means "purifier" and is also derived from the Greek kathartēs/καθαρτης.[8][7]

The exact taxonomic placement of the American Black Vulture and the remaining six species of New World Vultures remains unclear.[9] Though both are similar in appearance and have similar ecological roles, the New World and Old World Vultures evolved from different ancestors in different parts of the world. Just how different the two are is currently under debate, with some earlier authorities suggesting that the New World vultures are more closely related to storks.[10] More recent authorities maintain their overall position in the order Falconiformes along with the Old World Vultures[11] or place them in their own order, Cathartiformes.[12] The South American Classification Committee has removed the New World Vultures from Ciconiiformes and instead placed them in Incertae sedis, but notes that a move to Falconiformes or Cathartiformes is possible.[9]

There are three subspecies of American Black Vulture:

  • C. a. atratus, named by the German ornithologist Johann Matthäus Bechstein in 1793, is known as the North American Black Vulture. It is the nominate subspecies. It is approximately the same size as C. a. foetens, but its plumage is not as dark. Its range stretches from northern Mexico through Texas and the southern United States north to the Carolinas.[13]
  • C. a. brasiliensis named by Charles Lucien Jules Laurent Bonaparte in 1850, is known as the Southern American Black Vulture. It is smaller than C. a. atratus and C. a. foetens. The light markings on the undersides of the primaries are whiter and broader than those of the other subspecies, and the underwing coverts are lighter than those of C. a. foetens.[13] It is found in Central America and northern South America. To the south, the range extends to the coastal regions of Peru on the west and the lowlands of Bolivia on the east. To the north, it stretches to Sonora in western Mexico and San Luis Potosí in eastern Mexico. It is not found in high-altitude regions.[13]
  • C. a. foetens, named by Martin Lichtenstein in 1817, is known as the Andean Black Vulture. It is approximately the same size as C. a. atratus.[13] The markings on the undersides of the primaries are smaller than those of the other subspecies, and the underwing coverts are darker. It is found in the Andes range, from northern Ecuador through Peru, northern Bolivia, Paraguay, Uruguay, and the lowlands of Chile.[13]

Evolutionary history of Coragyps

From the Early to the Late Pleistocene, a prehistoric species of Black Vulture, Coragyps occidentalis, known as the Pleistocene Black Vulture or, somewhat in error, the "Western Black Vulture", occurred across the present species' range. This bird did not differ much from the American Black Vulture of today except in size; it was some 10-15% larger, and had a relatively flatter and wider bill.[14] It filled the same ecological niche as the living form,[15] and indeed seems to have evolved into it by decreasing in size during the last ice age.[16][17] Well documented from fossil bones, the genus Coragyps gives a rare glimpse in the evolutionary dynamics of two chronospecies. The final stages of this evolutionary transformation must have been witnessed by humans: a subfossil bone of the extinct species was found in an Paleo Indian to Early Archaic (9000-8000 years BCE) midden at Five Mile Rapids near The Dalles, Oregon.[18]

Fossil (or subfossil) Black Vultures cannot necessarily be attributed to the Pleistocene or the recent species without further information: the same size variation found in the living bird was also present in its larger prehistoric relative. Thus, in 1968, Hildegarde Howard separated the Mexican birds as Coragyps occidentalis mexicanus as opposed to the birds from locations farther north (such as Rancho La Brea) which constituted the nominate subspecies C. o. occidentalis.[19] The southern birds were of the same size as present-day North American Black Vultures and can only be distinguished by their somewhat stouter tarsometatarsus and the flatter and wider bills, and even then only with any certainty if the location where the fossils were found is known.[20] As the Pleistocene and current American Black Vultures form an evolutionary continuum rather than splitting into two or more lineages, some include the Pleistocene taxa in C. atratus.[17]

Description

Coragyps atratus brasiliensis

The American Black Vulture is a very large bird of prey, measuring 65 centimeters (25.5 in) in length, with a 1.5 meter (5 ft) wingspan and a weight of 2-2.75 kilograms (4.5-6 lb). Its plumage is mainly glossy black. The head and neck are featherless and the skin is dark gray and wrinkled.[21] The iris of the eye is brown and has a single incomplete row of eyelashes on the upper lid and two rows on the lower lid.[22] The legs are grayish white,[23] while the two front toes of the foot are long and have small webs at their bases.[2] The feet are flat, relatively weak, and are poorly adapted to grasping; the talons are also not designed for grasping, as they are relatively blunt.[24]

The nostrils are not divided by a septum, but rather are perforate; from the side one can see through the beak.[25] The wings are broad but relatively short. The bases of the primary feathers are white, producing a white patch on the underside of the wing's edge, which is visible in flight. The tail is short and square, barely reaching past the edge of the folded wings.[21] The subspecies differ in size according to Bergmann's Rule and the amount of white underwing coloration also varies. As it probably forms a cline over its entire range, the species is often considered monotypic.

A leucistic Coragyps atratus brasiliensis was observed in Piñas, Ecuador in 2005. It had white plumage overall, with only the tarsus and tail as well as some undertail feathers being black. It was not an albino as its skin seemed to have had the normal, dark color and it was part of a flock of some twenty normally-plumaged individuals.[26]

Distribution and habitat

The American Black Vulture has a Nearctic and Neotropic distribution.[27] Its range includes the southeastern United States, Mexico, Central America and South America. It is usually a permanent resident throughout its range, although birds at the extreme north of its range may migrate short distances, and others across their range may undergo local movements in unfavourable conditions.[28] In South America, its range stretches to central Chile and Argentina.[29] It also is found on the islands of the Caribbean.[1] It prefers open land interspersed with areas of woods or brush.[30] It is also found in moist lowland forests, shrublands and grasslands, wetlands and swamps, pastures, and heavily degraded former forests.[1] Preferring lowlands, it is rarely seen in mountainous areas. It is usually seen soaring or perched on fence posts or dead trees.[23]

Ecology and behavior

An group of American Black Vultures perching on a fence

It soars high while searching for food, holding its wings horizontally when gliding. It flaps in short bursts which are followed by short periods of gliding.[31] Its flight is less efficient than that of other vultures, as the wings are not as long, forming a smaller sail surface.[32] In comparison with the Turkey Vulture, the American Black Vulture flaps its wings more frequently during flight. It is known to regurgitate when approached or disturbed, which assists in predator deterrence and taking flight by decreasing its takeoff weight. Like all New World Vultures, the American Black Vulture often defecates on its own legs, using the evaporation of the water in the feces and/or urine to cool itself, a process known as urohydrosis.[2] It cools the blood vessels in the unfeathered tarsi and feet, and causes white uric acid to streak the legs. Because it lacks a syrinx, the American Black Vulture, like other New World Vultures, has very few vocalization capabilities.[2] It is generally silent, but can make soft hisses and grunts. The American Black Vulture is gregarious, and roosts in large groups.[33] In areas where their ranges overlap, the American Black Vulture will roost on the bare branches of dead trees with groups of Turkey Vultures.[32] The American Black Vulture generally forages in groups; a flock of Black Vultures can easily drive a Turkey Vulture, which is generally solitary while foraging, from a carcass.[33]

Like the Turkey Vulture, this vulture is often seen standing in a spread-winged stance.[21] The stance is believed to serve multiple functions: drying the wings, warming the body, and baking off bacteria. This same behavior is displayed by other New World vultures, Old World vultures, and storks.[34]

Diet

An American Black Vulture at a garbage dump

In natural settings, the American Black Vulture eats mainly carrion.[35] In areas populated by humans, it may scavenge at garbage dumps, but also takes eggs and decomposing plant material and can kill or injure new-born or incapacitated mammals. Like other vultures, it plays an important role in the ecosystem by disposing of carrion which would otherwise be a breeding ground for disease.[36] The American Black Vulture locates food either by sight or by following New World Vultures of the genus Cathartes to carcasses. These vultures—the Turkey Vulture, the Lesser Yellow-headed Vulture, and the Greater Yellow-headed Vulture— forage by smell, an ability which is uncommon in the avian world. They fly low to the ground to pick up the scent of ethyl mercaptan, a gas produced by the beginnings of decay in dead animals.[37] Their heightened ability to detect odors allows them to search for carrion below the forest canopy.[34] King Vultures and American Black Vultures, which lack the ability to smell carrion, follow them to carcasses.[36] It is aggressive when feeding, and may chase the slightly larger Turkey Vulture from carcasses.[35]

The American Black Vulture also occasionally feeds on livestock or deer. It is the only species of New World vulture which preys on cattle. It occasionally harasses cows which are giving birth, but primarily preys on new-born calves. In its first few weeks, a calf will allow vultures approach it. The vultures swarm the calf in a group, then peck at the calf's eyes, or at the nose or the tongue. The calf then goes into shock and is killed by the vultures.[38]

Reproduction

The timing of American Black Vultures' breeding season varies with the latitude at which they live. In the United States, birds in Florida begin breeding as early as January, for example, while those in Ohio generally do not start before March.[39] In South America, Argentinian and Chilean birds begin egg-laying as early as September, while those further north on the continent typically wait until October. Some in South America breed even later than that—American Black Vultures in Trinidad typically do not start until November, for example, and those in Ecuador may wait until February.[39] Pairs are formed following a courtship ritual which is performed on the ground: several males circle a female with their wings partially open as they strut and bob their heads.[21] They sometimes perform courtship flights, diving or chasing each other over their chosen nest site.[39]

The American Black Vulture lays its eggs on the ground in a wooded area, a hollow log, or some other cavity, seldom more than 3 meters (10 ft) above the ground.[21] While it generally does not use any nesting materials, it may decorate the area around the nest with bits of brightly-colored plastic, shards of glass, or metal items such as bottle caps.[30] Clutch size is generally two eggs, though this can vary from one to three. The egg is oval and on average measures 7.56 by 5.09 centimeters (3 by 2 in). The smooth, gray-green, bluish, or white shell is variably blotched or spotted with lavender or pale brown around the larger end.[30] Both parents incubate the eggs, which hatch after 28 to 41 days.[30] Upon hatching, the young are covered with white down.[35] Both parents feed the nestlings, regurgitating food at the nest site. The young remain in the nest for two months, and after 75 to 80 days they are able to fly skillfully.[32]

Relationship with humans

A flock of American Black Vultures on a cow carcass

The American Black Vulture is considered a threat by cattle ranchers due to its predation on newborn cattle. The droppings produced by American Black Vultures and other vultures can harm or kill trees and other vegetation.[40] The American Black Vulture can be held in captivity, though the Migratory Bird Treaty Act only allows this in the case of animals which are injured or unable to return to the wild.[41] It receives special legal protections under the Migratory Bird Treaty Act of 1918 in the United States,[3] by the Convention for the Protection of Migratory Birds in Canada,[42] and by the Convention for the Protection of Migratory Birds and Game Mammals in Mexico.[42] In the United States it is illegal to take, kill, or possess American Black Vultures and violation of the law is punishable by a fine of up to 15,000 US dollars and imprisonment of up to six months.[41] It is listed as a species of Least Concern by the IUCN Red List. Populations appear to remain stable, and it has not reached the threshold of inclusion as a threatened species, which requires a decline of more than 30 percent in ten years or three generations.[1]

The American Black Vulture appears in a variety of Maya hieroglyphics in Mayan codices. It is normally connected with either death or as a bird of prey. The vulture’s glyph is often shown attacking humans. This species lacks the religious connections that the King Vulture has. While some of the glyphs clearly show the American Black Vulture’s open nostril and hooked beak, some are assumed to be this species because they are vulture-like but lack the King Vulture’s knob and are painted black.[43]

This vulture has appeared on two stamps, that of Guyana in 1990 and Nicaragua in 1994.[44]

Footnotes

  1. ^ a b c d e "Coragyps atratus". 2007 IUCN Red List. BirdLife International. Retrieved 2007-11-03.
  2. ^ a b c d Feduccia, J. Alan (1999). The Origin and Evolution of Birds. Yale University Press. p. 116. ISBN 0226056414.
  3. ^ a b "Birds Protected by the Migratory Bird Treaty Act". US Fish & Wildlife Service. Retrieved 2007-10-14.
  4. ^ Holloway, Joel Ellis (2003). Dictionary of Birds of the United States: Scientific and Common Names. Timber Press. p. 59. ISBN 0881926000.
  5. ^ Whitaker, William. "Words by William Whitaker". Retrieved 2007-11-05.
  6. ^ Simpson, D.P. (1979). Cassell's Latin Dictionary (5 ed.). London: Cassell Ltd. p. 883. ISBN 0-304-52257-0.
  7. ^ a b Ietaka, Taro. "Moving Beyond Common Names". Retrieved 2007-11-05.
  8. ^ Liddell, Henry George (1980). Greek-English Lexicon, Abridged Edition. Oxford: Oxford University Press. ISBN 0-19-910207-4. {{cite book}}: Unknown parameter |coauthor= ignored (|author= suggested) (help)
  9. ^ a b Remsen, J. V., Jr.; C. D. Cadena; A. Jaramillo; M. Nores; J. F. Pacheco; M. B. Robbins; T. S. Schulenberg; F. G. Stiles; D. F. Stotz & K. J. Zimmer. 2007. A classification of the bird species of South America. South American Classification Committee. Retrieved on 2007-10-15
  10. ^ Sibley, Charles G. and Burt L. Monroe. 1990. Distribution and Taxonomy of the Birds of the World. Yale University Press. ISBN 0-300-04969-2. Accessed 2007-04-11.
  11. ^ Sibley, Charles G., and Jon E. Ahlquist. 1991. Phylogeny and Classification of Birds: A Study in Molecular Evolution. Yale University Press. ISBN 0-300-04085-7. Accessed 2007-04-11.
  12. ^ Ericson, Per G. P.; Anderson, Cajsa L.; Britton, Tom; Elżanowski, Andrzej; Johansson, Ulf S.; Kallersjö, Mari; Ohlson, Jan I.; Parsons, Thomas J.; Zuccon, Dario & Mayr, Gerald (2006): Diversification of Neoaves: integration of molecular sequence data and fossils. Biology Letters online: 1-5. doi:10.1098/rsbl.2006.0523 PDF preprint Electronic Supplementary Material (PDF)
  13. ^ a b c d e Blake, Emmet Reid (1953). Birds of Mexico: A Guide for Field Identification. University of Chicago Press. p. 267. {{cite book}}: Unknown parameter |ibsn= ignored (help)
  14. ^ Fisher, Harvey L (1944). "The skulls of the Cathartid vultures" (PDF). Condor. 46 (6): 272–296. Retrieved 2007-11-03. {{cite journal}}: Cite has empty unknown parameter: |coauthors= (help)
  15. ^ Hertel, Fritz (1995). "Ecomorphological indicators of feeding behavior in Recent and fossil raptors" (PDF). Auk. 12 (4): 890–903. Retrieved 2007-11-03. {{cite journal}}: Cite has empty unknown parameter: |coauthors= (help)
  16. ^ Howard, Hildegarde (1962). "Bird Remains from a Prehistoric Cave Deposit in Grant County, New Mexico" (PDF). Condor. 64 (3): 241–242. Retrieved 2007-11-03.
  17. ^ a b Steadman, David W (1994). "New Information on the Late Pleistocene Birds from San Josecito Cave, Nuevo Leon, Mexico" (PDF). Condor. 96 (3): 577–589. Retrieved 2007-11-03. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  18. ^ Miller, Loye (1957). "Bird Remains from a Prehistoric Cave Deposit in Grant County, New Mexico" (PDF). Condor. 59 (1): 59–63. Retrieved 2007-11-03.
  19. ^ Howard, Hildegarde (1968). "Limb measurements of the extinct vulture, Coragyps occidentalis". Papers of the Archaeological Society of New Mexico. 1: 115–127.
  20. ^ Arroyo-Cabrales, Joaquin (2003). "Catálogo de los ejemplares tipo procedentes de la Cueva de San Josecito, Nuevo León, México ("Catalogue of the type specimens from San Josecito Cave, Nuevo León, Mexico")" (PDF). Revista Mexicana de Ciencias Geológicas. 20 (1): 79–93. Retrieved 2007-11-03. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  21. ^ a b c d e Terres, J. K. (1980). The Audubon Society Encyclopedia of North American Birds. New York, NY: Knopf. p. 959. ISBN 0394466519.
  22. ^ Fisher, Harvey I. (February), "The Pterylosis of the Andean Condor", Condor, 44 (1): 30–32 {{citation}}: Check date values in: |date= and |year= / |date= mismatch (help)
  23. ^ a b Peterson, Roger Tory (2001). A Field Guide to Western Birds. Houghton Mifflin Field Guides. p. 182. ISBN 061813218X.
  24. ^ "2007". Britannica Concise Encyclopedia. Encyclopædia Britannica. Retrieved 2007-10-14.
  25. ^ Allaby, Michael (1992). The Concise Oxford Dictionary of Zoology. Oxford, UK: Oxford University Press. p. 348. ISBN ISBN 0192860933. {{cite book}}: Check |isbn= value: invalid character (help)
  26. ^ Hosner, Peter A (2006). "Observations of plumage pigment aberrations of birds in Ecuador, including Ramphastidae" (PDF). Boletín de la Sociedad Antioqueña de Ornitología. 16 (1): 30–42. Retrieved 2007-11-03. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  27. ^ Bull, John L (1998). Bull's Birds of New York State. Cornell University Press. p. 138. ISBN 0801434041. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  28. ^ Buckley, N. J. (1999). Black Vulture (Coragyps atratus). In The Birds of North America, No. 411 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.
  29. ^ Hilty, Stephen L. (1977). A Guide to the Birds of Colombia. Princeton University Press. p. 88. ISBN 069108372X.
  30. ^ a b c d Harrison, Hal H. (1979). A Field Guide to Western Birds' Nests. Houghton Mifflin Field. p. 33. {{cite book}}: Unknown parameter |ibsn= ignored (help)
  31. ^ Robbins, C S. (2001). Birds of North America: A Guide to Field Identification. St. Martin's Press. p. 66. ISBN 1582380902. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  32. ^ a b c Fergus, Charles (2003). Wildlife of Virginia and Maryland Washington D.C. Stackpole Books. p. 172. ISBN 0811728218.
  33. ^ a b "All About Birds: Black Vulture". Cornell Lab of Ornithology. 2003. Retrieved 2007-11-04.
  34. ^ a b Snyder, Noel F. R. and Helen Snyder (2006). Raptors of North America: Natural History and Conservation. Voyageur Press. p. 45. ISBN 0760325820.
  35. ^ a b c Reader's Digest Editors (2005). Book Of North American Birds. Reader's Digest. p. 11. ISBN 0895773511. {{cite book}}: |last= has generic name (help)
  36. ^ a b Gomez, LG; Houston, DC; Cotton, P; Tye, A (1994). "The role of greater yellow-headed vultures Cathartes melambrotus as scavengers in neotropical forest". Ibis. 136 (2): 193–196. Retrieved 2007-10-03.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  37. ^ Muller-Schwarze, Dietland (2006). Chemical Ecology of Vertebrates. Cambridge University Press. p. 350. ISBN 0521363772.
  38. ^ Paulik, Laurie (2007-08-06). "Vultures and Livestock". AgNIC Wildlife Damage Management Web. Retrieved 2007-10-15.
  39. ^ a b c Ferguson-Lees, James (2001). Raptors of the World. London: Christopher Helm. p. 306. ISBN 0-7136-8026-1. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  40. ^ Paulik, Laurie (2007-08-06). "Vultures". AgNIC Wildlife Damage Management Web. Retrieved 2007-10-15.
  41. ^ a b "Migratory Bird Treaty Act". US Code Collection. Cornell Law School. Retrieved 2007-10-14.
  42. ^ a b "Game and Wild Birds: Preservation". US Code Collection. Cornell Law School. Retrieved 2007-10-29.
  43. ^ Tozzer, Alfred Marston (1910). Animal Figures in the Maya Codices. Harvard University. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  44. ^ "Black Vulture". Bird Stamps. Retrieved 2007-11-07.

External links

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