Lesser Yellow-headed Vulture

Taxobox
name = Lesser Yellow-headed Vulture

---

image_caption = Sketch of underside view in flight
status = LC
status_system = iucn3.1
status_ref =
regnum = Animalia
phylum = Chordata
classis = Aves
ordo = Falconiformes (disputed)
familia = Cathartidae
genus = "Cathartes"
species = "C. burrovianus"
binomial = "Cathartes burrovianus"
binomial_authority = Cassin, 1845
synonyms =
range_

range_map_width=200px
range_map_caption = Breeding range (yellow).

The Lesser Yellow-headed Vulture, "Cathartes burrovianus", also known as the Savannah Vulture, is a species of bird in the New World Vulture family Cathartidae. It was considered to be the same species as the Greater Yellow-headed Vulture until they were split in 1964. It is found in Mexico, Central America, and South America in seasonally wet or flooded lowland grassland, swamps, and heavily degraded former forest. It is a large bird, with a wingspan of 150-165 centimeters (59-65 in). The body plumage is black, and the head and neck, which are featherless, are pale orange with red or blue areas. It lacks a syrinx, so therefore its vocalizations are limited to grunts or low hisses.

The Lesser Yellow-headed Vulture feeds on carrion and locates carcasses by sight and by smell, an ability which is rare in birds. It is dependent on larger vultures, such as the King Vulture, to open the hides of larger animal carcasses as its bill is not strong enough to do this. Like other New World Vultures, the Lesser Yellow-headed Vulture utilizes thermals to stay aloft with minimal effort. It lays its eggs on flat surfaces, such as the floors of caves, or in the hollows of stumps. It feeds its young by regurgitation.

Taxonomy

The Lesser Yellow-headed Vulture was first described in 1845 by John Cassin.cite journal|last= Cassin |first= John |coauthors= |month= |year= |title= [untitled] |journal= Proceedings of the Academy of Natural Science of Philadelphia |volume= 2|issue=8 |pages=212 | quote = Near Veracruz, Mexico.] It is sometimes recognized as having two subspecies. The first, "Cathartes burrovianus urubitinga", described by Austrian ornithologist August von Pelzeln in 1851, is the larger of the two and is found from Argentina north to Colombia, while the nominate subspecies, "Cathartes burrovianus burrovianus", is smaller and found from northwestern South America through Central America to Mexico.Citation| last = Amadon| first = Dean| title = Notes on the Taxonomy of Vultures| journal = Condor| volume = 79 | issue =4| pages = 413-416| year = 1977 | url = http://elibrary.unm.edu/sora/Condor/files/issues/v079n04/p0413-p0416.pdf ] The Lesser Yellow-headed Vulture's genus, "Cathartes", means "purifier" and is from the Latinized form of the Greek "kathartēs"/καθαρτης. [ cite book|last=Liddell| first=Henry George|coauthor=Robert Scott|year=1980|title=Greek-English Lexicon, Abridged Edition |publisher=Oxford University Press|location= Oxford|isbn= 0-19-910207-4] The common name, vulture, is derived from the Latin word "vulturus", which means "tearer" and is a reference to its feeding habits.cite book
last =Holloway
first =Joel Ellis
title =Dictionary of Birds of the United States: Scientific and Common Names
publisher =Timber Press
date =2003
pages =59
url = http://books.google.com/books?id=41knpiVqnKYC&pg=PA59&dq=Cathartes+aura+subject:%22Nature+/+Birds+%26+Birdwatching%22&as_brr=3&sig=YS_oepqlw59T9RxDny5KFtPliSQ
isbn =0881926000]

The exact taxonomic placement of the Lesser Yellow-headed Vulture and the remaining six species of New World Vultures remains unclear. 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. [Sibley, Charles G. and Burt L. Monroe. 1990. " [http://books.google.com/books?vid=ISBN0300049692 Distribution and Taxonomy of the Birds of the World] ". Yale University Press. ISBN 0-300-04969-2. Accessed 2007-04-11.] More recent authorities maintain their overall position in the order Falconiformes along with the Old World Vultures [Sibley, Charles G., and Jon E. Ahlquist. 1991. " [http://books.google.com/books?vid=ISBN0300040857 Phylogeny and Classification of Birds: A Study in Molecular Evolution] ". Yale University Press. ISBN 0-300-04085-7. Accessed 2007-04-11.] or place them in their own order, Cathartiformes. [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 [http://www.systbot.uu.se/staff/c_anderson/pdf/neoaves.pdf PDF preprint] [http://royalsociety.metapress.com/media/public/contributionsupplementalmaterials/0/5/8/3/058352377848735w/archive1.pdf Electronic Supplementary Material] (PDF)] 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.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. [http://www.museum.lsu.edu/~Remsen/SACCBaseline.html "A classification of the bird species of South America."] South American Classification Committee. Retrieved on 2007-10-15]

Description

The Lesser Yellow-headed Vulture is 53-65 centimeters (21-25.5 in) in length, with a wingspan of 150-165 centimeters (59-65 in) and a tail length of 19-24 centimeters (7.5-9.5 in).cite book
last =Ferguson-Lees
first =James
coauthors =David A. Christie
title =Raptors of the World
publisher =Houghton Mifflin Field Guides
date =2001
pages =86
url = http://books.google.com/books?id=hlIztc05HTQC&pg=PA86&dq=Cathartes+aura+subject:%22Nature+/+Birds+%26+Birdwatching%22&as_brr=3&sig=PXtI2FVjA_oKlMWeYoD7-msqZI0#PPA86,M1 | isbn =0618127623 ] Its plumage is black with a green sheen. The throat and the sides of the head are featherless. The head and neck are bare of feathers, and the skin is yellow, with a reddish forehead and nape and a gray-blue crown. The irises of its eyes are red, its legs are white, and its beak is flesh-colored. The eye has a single incomplete row of eyelashes on the upper lid and two rows on the lower lid.Citation| last = Fisher| first = Harvey I.| title = The Pterylosis of the Andean Condor | journal = Condor| volume = 44 | issue = 1| pages = 30-32| date = February| year = 1942| url = http://links.jstor.org/sici?sici=0010-5422%28194201%2F02%2944%3A1%3C30%3ATPOTAC%3E2.0.CO%3B2-1&size=LARGE&origin=JSTOR-enlargePage] The tail is rounded and relatively short for a vulture; the tip of the closed wing extends beyond the tail.cite book
last =Blake
first =Emmett Reid
title =Manual of Neotropical Birds
publisher =University of Chicago Press
date =1977
pages =262
url =http://books.google.com/books?id=YP0AX3LW8jYC&pg=RA2-PA262&dq=Cathartes+melambrotus+%2B+black&ie=ISO-8859-1&sig=h4ARGewxVhakCgLiJQcZwCF_iho
isbn =0226056414 ] Immature Lesser Yellow-headed Vultures have browner plumage, a dusky head, and a white nape.cite book
last =Hilty
first =Stephen L.
title =A Guide to the Birds of Colombia
publisher =Princeton University Press
date =1977
pages =88
url =http://books.google.com/books?id=1k5fV_hQqE8C&pg=PA88&dq=Cathartes+melambrotus&as_brr=0&sig=tFHSOoZQy1Tc2nFxnoV3f8lj2Cs
isbn =069108372X ]

The beak is thick, rounded, and hooked at the tip.cite book| last =Terres| first =J. K.| authorlink =John Kenneth Terres| title =The Audubon Society Encyclopedia of North American Birds| publisher =Knopf| date =1980| location =New York, NY| pages = 957| isbn = 0394466519 ] The front toes are long with small webs at their bases and are not adapted to grasping. The opening of the nostril is longitudinal, and the nostrils lack a septum. Like all New World Vultures, the Lesser Yellow-headed Vulture lacks a syrinx, and is therefore unable to make any sound other than a low hiss. [cite book
last =Feduccia
first =J. Alan
title =The Origin and Evolution of Birds
publisher =Yale University Press
date =1999
pages =300
url = http://books.google.com/books?id=8QRKV7eSqmIC&pg=PA300&dq=Cathartes+melambrotus+%2B+black&as_brr=0&ie=ISO-8859-1&sig=BjxPgGtWEdfcd3N3O9WBACwOiDk#PPA300,M1
isbn =0226056414 ]

It differs in appearance from the similar Greater Yellow-headed Vulture in several ways. It is smaller than the Greater Yellow-headed Vulture and has a shorter, thinner tail. The plumage is browner than the Greater Yellow-headed Vulture's dark, glossy black plumage. Its legs are lighter in color and its head is more orange and less yellow than that of the Greater Yellow-headed Vulture. Its flight is also less steady than that of the Greater Yellow-headed Vulture. The Lesser Yellow-headed Vulture also prefers to live in savannas instead of the Greater Yellow-headed Vulture's forests and it is less heavily built.Citation| last = Amadon| first = Dean| title = Notes on the Taxonomy of Vultures| journal = Condor| volume = 79 | issue =4| pages = 413-416| year = 1977 | url = elibrary.unm.edu/sora/Condor/files/issues/v079n04/p0413-p0416.pdf ]

Distribution and habitat

It is found in Argentina, Belize, Bolivia, Brazil, Chile, Colombia, Costa Rica, Ecuador, El Salvador, French Guiana, Guatemala, Guyana, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, Suriname, Uruguay, and Venezuela.Its natural habitats are subtropical or tropical seasonally wet or flooded lowland grassland, swamps, mangroves, and heavily degraded former forest.cite web
author =BirdLife International
title =Cathartes burrovianus
publisher =IUCN Red List of Threatened Species
date= 2004
url =http://www.iucnredlist.org/search/details.php/49649/all
accessdate = 2007-10-02 ] It may wander over dry fields and clearings. It is not generally found in high-altitude regions.

Ecology and behavior

The Lesser Yellow-headed Vulture flies solitarily, with wings held in a dihedral position. It glides at a low altitude over wetlands while locating food, and perches on fence posts or on other low perches. When flying, it travels alone and is rarely found in groups. The flight of the lesser Yellow-Headed is an example of static soaring flight, which uses thermals to maintain altitude without the need to flap its wings. This vulture rarely soars high in the air, preferring low altitudes.Citation| last =Howell| first = Steve N.G.| last2 = Webb| first2 = Sophie| title = A Guide to the Birds of Mexico and Northern Central America| place= New York| publisher = Oxford University Press| year = 1995|pages = 175|isbn = 0-19-854012-4 ] This bird is believed to be somewhat migratory in response to the changes in water level where it lives. The Lesser Yellow-headed Vulture, like other New World Vultures, has the unusual habit of urohydrosis, in which it urinates or defecates on its legs to cool them by evaporation. [cite book
last =Sibley, Charles G. and Jon E. Ahlquist
title =Phylogeny and Classification of Birds: A Study in Molecular Evolution
publisher =Yale University Press
date =1991
url= http://books.google.com/books?vid=ISBN0300040857
isbn = 0-300-04085-7]

Diet

The Lesser Yellow-headed Vulture is a scavenger and subsists almost entirely on carrion.cite web
last =Channing
first =Keith
title =Lesser Yellow-headed Vulture
publisher =The Hawk Conservancy
url =http://www.hawk-conservancy.org/priors/yellowheadedvulture.shtml
accessdate = 2007-10-25 ] It will eat roadkill or the carcass of any animal, but is also known to hunt for food, especially small aquatic animals in marshes. It prefers fresh meat, but often cannot make the first cut into the carcass of a larger animal because its beak is not strong enough to tear into the tough hide. The Lesser Yellow-headed Vulture will no longer feed on a piece of carrion once the meat is in a state of extreme decay, as it becomes contaminated with microbial toxins. Like other vultures, it plays an important role in its ecosystem by disposing of carrion which would otherwise be a breeding ground for disease.cite journal
last =Gomez, LG; Houston, DC; Cotton, P; Tye, A
title = The role of greater yellow-headed vultures Cathartes melambrotus as scavengers in neotropical forest
journal = Ibis
volume =136
issue =2
pages =193–196
publisher =
location =
date =1994
url =http://md1.csa.com/partners/viewrecord.php?requester=gs&collection=ENV&recid=3646491&q=Cathartes+melambrotus&uid=791396595&setcookie=yes
accessdate = 2007-10-03
doi = 10.1111/j.1474-919X.1994.tb01084.x ]

The Lesser Yellow-headed Vulture forages using its keen eyesight to locate carrion on the ground, but also uses its sense of smell, an ability which is uncommon in the avian world. It locates carrion by detecting the scent of ethyl mercaptan, a gas produced by the beginnings of decay in dead animals.The olfactory lobe of its brain responsible for processing smells is particularly large compared to other animals.cite book
last = Snyder, Noel F. R. and Helen Snyder
title =Raptors of North America: Natural History and Conservation
publisher =Voyageur Press
page=40
date =2006
url= http://books.google.com/books?id=g6aOgkIbEwEC&pg=PA40&dq=Cathartes+aura&as_brr=3&sig=Zc-vwBBgjWSMDx56CatOgteVOtI#PPA40,M1
isbn = 0760325820] This characteristic of New World Vultures has been used by humans: ethyl mercaptan is injected into pipelines, and engineers looking for leaks then follow the foraging vultures. [cite web
title =Avian Olfaction
publisher =Cornell University
url =http://instruct1.cit.cornell.edu/courses/psych396/student2002/hcs7/
accessdate = 2007-10-25 ]

King Vultures, which lack the ability to smell carrion, follow the Lesser Yellow-headed Vultures to carcasses, where the King Vulture tears open the skin of the dead animal. This allows the smaller Lesser Yellow-headed Vulture access to food, as it does not have a bill strong enough to tear the hide of larger animals. This is an example of mutual dependence between species. [cite book
last =Muller-Schwarze
first =Dietland
title =Chemical Ecology of Vertebrates
publisher =Cambridge University Press
page=350
date =2006
url= Chemical Ecology of Vertebrates
isbn = 0521363772] It is generally displaced from carcasses by both Turkey Vultures and King Vultures, due to their larger size.

Reproduction

Lesser Yellow-headed Vultures do not build nests, but rather lay eggs on the ground, cliff ledges, the floors of caves, or in the hollow of a tree. Eggs cream colored and heavily blotched with brown and gray spots, particularly around the larger end. Two eggs are generally laid. The chicks are altricial—they are blind, naked and relatively immobile upon hatching. The chicks do not grow their down feathers until later. The parents feed their young by regurgitating pre-digested food into their beak, where the chicks then drink it. Young fledge after two to three months.

Conservation

The Lesser Yellow-headed Vulture is a bird of Least Concern according to the IUCN, with an estimated global range of 7,800,000 square kilometers and a population of between 100,000 and 1,000,000 individuals. [BirdLife International (2007) Species factsheet: Cathartes burrovianus. Downloaded from http://www.birdlife.org on 6/10/2007 ] There is evidence that suggests a decline in the species' population, but it is not significant enough to warrant an upgrade in conservation status.

References

External links

* [http://www.arthurgrosset.com/sabirds/lesser%20yellow-headed%20vulture.html Lesser Yellow-headed Vulture photos and information]
* [http://vireo.acnatsci.org/search.html?Form=Search&SEARCHBY=Common&KEYWORDS=lesser+yellow-headed+vulture&showwhat=images&AGE=All&SEX=All&ACT=All&Search=Search&VIEW=All&ORIENTATION=All&RESULTS=24 Lesser Yellow-headed Vulture photo gallery] VIREO
* [http://home.scarlet.be/~tse98017/feb0615.jpgPhoto-Medium Res] ; [http://home.scarlet.be/~tse98017/2006feb.htm Article] home.scarlet.be
* [http://chandra.as.utexas.edu/~kormendy/brazilss/LessYelloheadVulture-1886ss.jpgPhoto-High Res] ; [http://chandra.as.utexas.edu/~kormendy/brazilbirds.html Article] chandra.as.utexas.edu