The lesser yellow-headed vulture (''Cathartes burrovianus'') also known as the savannah vulture, is a species of
bird
Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...
in the
New World vulture
The New World vulture or condor family, Cathartidae, contains seven extant species in five genera. It includes five extant vultures and two extant condors found in warm and temperate areas of the Americas. The "New World" vultures were widesprea ...
family Cathartidae. It was considered to be the same species as the
greater yellow-headed vulture
The greater yellow-headed vulture (''Cathartes melambrotus''), also known as the forest vulture, is a species of bird in the New World vulture family Cathartidae. It was considered to be the same species as the lesser yellow-headed vulture until ...
until they were split in 1964. It is found in Mexico, Central America, and South America in seasonally wet or flooded lowland
grassland
A grassland is an area where the vegetation is dominated by grasses ( Poaceae). However, sedge ( Cyperaceae) and rush ( Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur na ...
, swamps, and heavily degraded former forest. It is a large bird, with a wingspan of . 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
bird
Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...
s. It is dependent on larger vultures, such as the
king vulture
The king vulture (''Sarcoramphus papa'') is a large bird found in Central and South America. It is a member of the New World vulture family Cathartidae. This vulture lives predominantly in tropical lowland forests stretching from southern Mexic ...
, 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
thermal
A thermal column (or thermal) is a rising mass of buoyant air, a convective current in the atmosphere, that transfers heat energy vertically. Thermals are created by the uneven heating of Earth's surface from solar radiation, and are an example ...
s to stay aloft with minimal effort. It lays its
eggs
Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...
on flat surfaces, such as the floors of
cave
A cave or cavern is a natural void in the ground, specifically a space large enough for a human to enter. Caves often form by the weathering of rock and often extend deep underground. The word ''cave'' can refer to smaller openings such as sea ...
s, 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
John Cassin (September 6, 1813 – January 10, 1869) was an American ornithologist from Pennsylvania. He worked as curator and Vice President at the Philadelphia Academy of Natural Sciences and focused on the systemic classification of the Acad ...
. It is sometimes recognized as having two subspecies. The first, ''Cathartes burrovianus urubitinga'', described by Austrian ornithologist
August von Pelzeln
August von Pelzeln (10 May 1825, Prague – 2 September 1891 in Oberdöbling) was an Austrian ornithologist. He was a grandson to novelist Karoline Pichler (1769-1843). The lesser yellow-headed vulture's
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
, ''Cathartes'', means "purifier" and is from the
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
ized form of the
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
''kathartēs''/καθαρτης. The common name, vulture, is derived from the
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
word ''vulturus'', which means "tearer" and is a reference to its feeding habits.
The exact taxonomic placement of the lesser yellow-headed vulture and the remaining six species of
New World vulture
The New World vulture or condor family, Cathartidae, contains seven extant species in five genera. It includes five extant vultures and two extant condors found in warm and temperate areas of the Americas. The "New World" vultures were widesprea ...
s remains unclear. Although both are similar in appearance and have similar ecological roles, the New World and
Old World vultures
Old World vultures are vultures that are found in the Old World, i.e. the continents of Europe, Asia and Africa, and which belong to the family Accipitridae, which also includes eagles, buzzards, kites, and hawks.
Old World vultures are not clo ...
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
Storks are large, long-legged, long-necked wading birds with long, stout bills. They belong to the family called Ciconiidae, and make up the order Ciconiiformes . Ciconiiformes previously included a number of other families, such as herons an ...
. More recent authorities maintain their overall position in the order
Falconiformes
The order Falconiformes () is represented by the extant family Falconidae (falcons and caracaras) and a handful of enigmatic Paleogene species. Traditionally, the other bird of prey families Cathartidae (New World vultures and condors), Sagitt ...
along with the Old World vultures or place them in their own order, Cathartiformes. The
South American Classification Committee
The American Ornithological Society (AOS) is an ornithological organization based in the United States. The society was formed in October 2016 by the merger of the American Ornithologists' Union (AOU) and the Cooper Ornithological Society. Its ...
has removed the New World vultures from
Ciconiiformes
Storks are large, long-legged, long-necked wading birds with long, stout bills. They belong to the family called Ciconiidae, and make up the order Ciconiiformes . Ciconiiformes previously included a number of other families, such as herons a ...
and instead placed them in ''
Incertae sedis
' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertain ...
'', 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 ''A classification of the bird species of South America.'' South American Classification Committee. Retrieved on 2007-10-15 Like other New World vultures, the lesser yellow-headed vulture has a diploid chromosome number of 80.
Description
This is the lightest and smallest of the extant New World vultures despite sometimes measuring at least as long and longer winged than black vultures. The lesser yellow-headed vulture is in length, with a wingspan of and a tail length of . Its weight ranges from . 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
eyelash
An eyelash (also called lash) (Latin: ''Cilia'') is one of the hairs that grows at the edge of the eyelids. It grows in one layer on the edge of the upper and lower eyelids. Eyelashes protect the eye from debris, dust, and small particles and p ...
es on the upper lid and two rows on the lower lid.
The tail is rounded and relatively short for a vulture; the tip of the closed wing extends beyond the tail. Immature lesser yellow-headed vultures have browner plumage, a dusky head, and a white nape.
The beak is thick, rounded, and hooked at the tip.
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.
It differs in appearance from the similar
greater yellow-headed vulture
The greater yellow-headed vulture (''Cathartes melambrotus''), also known as the forest vulture, is a species of bird in the New World vulture family Cathartidae. It was considered to be the same species as the lesser yellow-headed vulture until ...
in several ways. It is smaller and is less heavily built 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-tinged than the more yellow head 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, as opposed to the preferred forest habitat of the greater yellow-headed vulture.
Besides the greater yellow-headed vulture, it is similar to the
turkey vulture
The turkey vulture (''Cathartes aura'') is the most widespread of the New World vultures. One of three species in the genus '' Cathartes'' of the family Cathartidae, the turkey vulture ranges from southern Canada to the southernmost tip of Sout ...
.
Distribution and habitat
It is found in Argentina,
Belize
Belize (; bzj, Bileez) is a Caribbean and Central American country on the northeastern coast of Central America. It is bordered by Mexico to the north, the Caribbean Sea to the east, and Guatemala to the west and south. It also shares a wate ...
Chile
Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...
Ecuador
Ecuador ( ; ; Quechua: ''Ikwayur''; Shuar: ''Ecuador'' or ''Ekuatur''), officially the Republic of Ecuador ( es, República del Ecuador, which literally translates as "Republic of the Equator"; Quechua: ''Ikwadur Ripuwlika''; Shuar: ' ...
French Guiana
French Guiana ( or ; french: link=no, Guyane ; gcr, label=French Guianese Creole, Lagwiyann ) is an overseas department/region and single territorial collectivity of France on the northern Atlantic coast of South America in the Guianas. ...
Mexico
Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...
,
Nicaragua
Nicaragua (; ), officially the Republic of Nicaragua (), is the largest country in Central America, bordered by Honduras to the north, the Caribbean to the east, Costa Rica to the south, and the Pacific Ocean to the west. Managua is the countr ...
,
Panama
Panama ( , ; es, link=no, Panamá ), officially the Republic of Panama ( es, República de Panamá), is a transcontinental country spanning the southern part of North America and the northern part of South America. It is bordered by Co ...
,
Paraguay
Paraguay (; ), officially the Republic of Paraguay ( es, República del Paraguay, links=no; gn, Tavakuairetã Paraguái, links=si), is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to th ...
,
Peru
, image_flag = Flag of Peru.svg
, image_coat = Escudo nacional del Perú.svg
, other_symbol = Great Seal of the State
, other_symbol_type = National seal
, national_motto = "Firm and Happy f ...
Uruguay
Uruguay (; ), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; while bordering ...
, and
Venezuela
Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...
.
Its natural
habitat
In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...
s are subtropical or tropical seasonally wet or flooded lowland
grassland
A grassland is an area where the vegetation is dominated by grasses ( Poaceae). However, sedge ( Cyperaceae) and rush ( Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur na ...
mangrove
A mangrove is a shrub or tree that grows in coastal saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evolution in severa ...
s, and heavily degraded former forest. It may wander over dry fields and clearings. It is not generally found in high-altitude regions.
This bird with its somehow crow-like aspect gave foot to the naming of the
Quebrada de los Cuervos
The Quebrada de los Cuervos (Spanish for ''Crows Ravine'') is an important landform in Treinta y Tres Department, Uruguay.
Crossed by the Yerbal Chico creek, it constitutes a natural protected area. This Important Bird Area (IBA) is inhabited by ...
(Crows Ravine) in
Uruguay
Uruguay (; ), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; while bordering ...
, where they dwell together with the
black vulture
The black vulture (''Coragyps atratus''), also known as the American black vulture, Mexican vulture, zopilote, urubu, or gallinazo, is a bird in the New World vulture family whose range extends from the northeastern United States to Peru, Cen ...
and the
turkey vulture
The turkey vulture (''Cathartes aura'') is the most widespread of the New World vultures. One of three species in the genus '' Cathartes'' of the family Cathartidae, the turkey vulture ranges from southern Canada to the southernmost tip of Sout ...
.
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
A thermal column (or thermal) is a rising mass of buoyant air, a convective current in the atmosphere, that transfers heat energy vertically. Thermals are created by the uneven heating of Earth's surface from solar radiation, and are an example ...
to maintain altitude without the need to flap its wings. This vulture rarely soars high in the air, preferring low altitudes. 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 vulture
The New World vulture or condor family, Cathartidae, contains seven extant species in five genera. It includes five extant vultures and two extant condors found in warm and temperate areas of the Americas. The "New World" vultures were widesprea ...
s, has the unusual habit of
urohidrosis
Urohidrosis (sometimes misspelled "urohydrosis") is the habit in some birds of defecating onto the scaly portions of the legs as a cooling mechanism, using evaporative cooling of the fluids. Several species of storks and New World vultures exhibi ...
, in which it urinates or defecates on its legs to cool them by evaporation.
Breeding
Lesser yellow-headed vultures do not build nests, but rather lay
eggs
Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...
on the ground, cliff ledges, the floors of caves, or in the hollow of a tree. Eggs are cream colored and heavily blotched with brown and gray spots, particularly around the larger end. Two eggs are generally laid. The chicks are
altricial
In biology, altricial species are those in which the young are underdeveloped at the time of birth, but with the aid of their parents mature after birth. Precocial species are those in which the young are relatively mature and mobile from the mome ...
—they are blind, naked and relatively immobile upon hatching. The chicks do not grow their
down feather
The down of birds is a layer of fine feathers found under the tougher exterior feathers. Very young birds are clad only in down. Powder down is a specialized type of down found only in a few groups of birds. Down is a fine thermal insulator an ...
s until later. The parents feed their young by regurgitating pre-digested food into their
beak
The beak, bill, or rostrum is an external anatomical structure found mostly in birds, but also in turtles, non-avian dinosaurs and a few mammals. A beak is used for eating, preening, manipulating objects, killing prey, fighting, probing for foo ...
, where the chicks then drink it. The young fledge after two to three months.
Feeding
The lesser yellow-headed vulture is a scavenger and subsists almost entirely on carrion. 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
An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...
by disposing of carrion which would otherwise be a breeding ground for disease.
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
Ethanethiol, commonly known as ethyl mercaptan, is an organosulfur compound with the formula CH3CH2SH. is a colorless liquid with a distinct odor. Abbreviated EtSH, it consists of an ethyl group (Et), CH3CH2, attached to a thiol group, SH. Its s ...
, a gas produced by the beginnings of decay in dead animals.
The olfactory lobe of its
brain
A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a ve ...
responsible for processing smells is particularly large compared to other animals. 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.
King vulture
The king vulture (''Sarcoramphus papa'') is a large bird found in Central and South America. It is a member of the New World vulture family Cathartidae. This vulture lives predominantly in tropical lowland forests stretching from southern Mexic ...
s, 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
Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...
between species. It is generally displaced from carcasses by both
turkey vulture
The turkey vulture (''Cathartes aura'') is the most widespread of the New World vultures. One of three species in the genus '' Cathartes'' of the family Cathartidae, the turkey vulture ranges from southern Canada to the southernmost tip of Sout ...
s and
king vulture
The king vulture (''Sarcoramphus papa'') is a large bird found in Central and South America. It is a member of the New World vulture family Cathartidae. This vulture lives predominantly in tropical lowland forests stretching from southern Mexic ...
s, due to their larger size.
Conservation
The lesser yellow-headed vulture is a bird of
Least Concern
A least-concern species is a species that has been categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. T ...
range
Range may refer to:
Geography
* Range (geographic), a chain of hills or mountains; a somewhat linear, complex mountainous or hilly area (cordillera, sierra)
** Mountain range, a group of mountains bordered by lowlands
* Range, a term used to i ...
lesser yellow-headed vulture
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 unt ...
lesser yellow-headed vulture
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 unt ...