Black-chested Buzzard-eagle
Encyclopedia
The Black-chested Buzzard-Eagle (Geranoaetus melanoleucus) is a bird of prey
of the hawk
and eagle
family
(Accipitridae
). It lives in open regions of South America
. This species
is also known as the Black Buzzard-eagle, Grey Buzzard-eagle or analogously with "eagle" or "eagle-buzzard" replacing "buzzard-eagle", or as the Chilean Blue Eagle. It is sometimes placed in the genus
Buteo
.
This is a huge eagle-like "buzzard
" ("hawk" in American terminology). It has a total length of 24-32 in (about 60–80 cm) and a wingspan of 58-79 in (149–200 cm). In the smaller G. m. australis subspecies, the weight is 3.7-7.1 lb. (1.7-3.2 kg), with no reported weights on the nominate subspecies. It is noted for its bulky, powerful-looking build. It is rather long- and broad-winged and the slightly tapering tail is short by comparison and colored black, with grey tips in fresh plumage. When perched, the wings cover the tail almost completely, giving the bird a unique near-tailess appearance when perched. The adult has a white underside, sometimes with fine blackish stripes; its upperparts are dark grey with a blackish, brownish or bluish hue. The feathers of the neck and the lowest dark feathers of the breast are somewhat elongated. Adults have an ash-grey-and-white zone on the wings, the silvery white seen clearly from afar. The female is distinguished by a reddish-cinnamon hue to the upper- and underwing secondaries and is considerably larger than the male.
The immature plumage
is reminiscent of that of the Great Black Hawk
(Buteogallus urubitinga). Its upperparts are deep brown, sometimes almost black, and it has no light wing patch. The underside is white or light buff
with heavy dark streaks on the breast and dark bars on the belly and thighs. It does not acquire the full adult plumage until 4–5 years old.
It is not very vocal, calling usually in flight and when close to the nest
. Some calls resemble a wild human laugh, others are a curlew
-like whistle. Occasionally flying birds give a high-pitched vocalization "kukukukuku".
The Black-chested Buzzard-Eagle is readily identified in flight by its short wedge-shaped tail scarcely protruding from its long, broad wings
. It is usually easy to make out the generally white underparts with the dark chest-band and tail if the birds are adult. Yet as this bird is usually encountered in the wild when it soars, you are less likely to see its grey upperparts.
is Latin
ized Ancient Greek
and means "black-and-white crane-eagle" or (if called Buteo melanoleucos) "black-and-white buzzard": Geranoaetus comes from Ancient Greek géranos (γέρανoς), "crane
" + aetós (ἆετός), "eagle". The "crane" reference is due to its grey upper wings and its loud cries. The alternative genus
name Buteo is simply the Latin term used for these hawks in Ancient Rome
, translating as "buzzard" (in the European sense). melanoleucus is from Ancient Greek mélan- (μέλαν-), "black-" + leukós (λευκός), "white". This refers to the contrasting coloration when seen from below.
When the Black-chested Buzzard-Eagle was first described by Louis Jean Pierre Vieillot
in 1819, it was placed in the genus
Spizaetus
, as Spizaetus melanoleucus. Today however, the monotypic genus Spizastur is merged in Spizaetus, and the Black-and-white Hawk-Eagle
, originally described as by Vieillot three years earlier as Buteo melanoleucus, is now known as Spizaetus melanoleucus. The earlier use of the specific epithet melanoleucus for the Black-and-white Hawk-Eagle technically precludes its use for the Black-chested Buzzard-Eagle, except when it is placed in Geranoaetus. In fact, in the mid-20th century Buteo fuscescens was the prevailing name for the Black-chested Buzzard-Eagle for some years, but it was eventually dismissed as erroneous. This specific name was established – as Spizaetus fuscescens – by Vieillot for the immature of the Black-chested Buzzard-Eagle at the very same time as he described the adult, because he could not believe that such differently-colored birds were conspecific
.
As the two birds are not placed in the same genus today, Article 59.3 of the ICZN
Code applies. According to this, a junior homonym replaced before 1961 is not rendered permanently invalid (as junior homonyms usually are) if "the substitute name is not in use" – which has been the case after Amadon's 1963 revision. Hence, in this case the scientific name Buteo melanoleucus can apply, even though the Black-and-white Hawk-Eagle was earlier described under exactly that name, while the senior homonym melanoleucus still applies to the latter species when placed in Spizaetus according to the usual ICZN rules. Consequently, the proper name to use for each bird has through a number of coincidences become the one the other species was described under.
:
The Black-chested Buzzard-Eagle is allied to the Buteo
hawks, and it is sometimes included with these. Other authors place it in the monotypic genus
Geranoaetus. Though the former seems to be more appropriate from a phylogenetic
standpoint, the latter is still used here, as much more research into phylogeny and hybridization has to take place before the correct taxonomy
of the buteonine
s can be resolved. It stands to note that the taxonomic and systematic dispute goes back to the early-mid 20th century already. However, it seems there is no real reason to suppose that the lineage of the Black-chested Buzzard-Eagle is North American in origin; fossil
s that might have been its ancestors at first sight differ in details and are more likely to belong to other buteonine lineages. Due to this species buteonine lineage, this species and the closely related Harpyhaliaetus
are not considered "true eagles", as are Aquila
eagles and "hawk-eagle
s", and are thus the largest extant type of the diverse buteonine lineage.
This species could be close to the White-tailed Hawk
(Buteo albicaudatus), and perhaps to the Grey-backed
(Leucopternis occidentalis), White
(L. albicollis), and Mantled Hawk
s (L. polionotus) which it resembles in habitus
except for being larger. Its closest living relatives may well be the Red-backed (B. polyosoma) and Puna Hawks (B. poecilochrous). Particularly some populations of the former look like small Black-chested Buzzard-Eagles. The Barred Hawk
(L. princeps) looks similar to the Black-chested Buzzard-Eagle in general color pattern, though the tail differs much in shape, size, and the bright white central band stands out.
The relationship of the Black-chested Buzzard-Eagle to the prehistoric
genera Titanohierax from the Caribbean
and the Pan-American Amplibuteo also warrant more study. The crab-hawks (Buteogallus
) and the solitary "eagles" (Harpyhaliaetus
) seem to be allied with the latter, to the extent that these three genera might be united in Buteogallus. That genus in the present restricted sense contains species also quite similar in habitus and size to the Black-chested Eagle-buzzard.
s have been placed in Geranoaetus, but those from North America
have since been moved elsewhere:
Bones indistinguishable from those of living Black-chested Buzzard-Eagles were found in a spring deposit at the Baños de Ciego Montero in Cienfuegos Province
, Cuba
. A partial left carpometacarpus
– Specimen AMNH
FR 6190 – as well as a fingerbone probably date from some time in the Pleistocene
, during the last ice age
. Its contemporary close relatives on Cuba, as far as it is known, consisted of the gigantic eagle-like buteonine
hawks which were clearly distinct by size alone, while the Pleistocene record of similar-sized birds from continental North America is from the far west.
with sparse vegetation, shrubland or (in the south of its range) Nothofagus
forest, where it spends a lot of time soaring
in thermal
s and vertical draft
s while looking for prey
. It requires large territories with suitable habitat
, the páramo
s at the north of its range, for example, while providing the latter, fail to provide the former, and thus it has only been recorded in the largest patches of such habitat, such as Páramo de Frontino. Most common between about 5000 feet (1,524 m) and 15000 feet (4,572 m) ASL
, it rarely ventures into the lowlands.
It is most conspicuous in the mid-morning and afternoon, when individuals will seek out places which provide the best soaring conditions, such as north and west facing slopes and ridges. Apparently, their main interest at these times is aerial play and display; they tend to ignore places where food is more plentiful or easily hunted in favor of simply soaring alone or in pairs in strong air currents.
The food of this carnivore
consists mainly of mid-sized mammal
s; the introduced European Rabbit
(Oryctolagus cuniculus) seems to have become a key prey item. The Black-chested Buzzard-Eagle is helpful to farmers by keeping down the numbers of the rabbits, which can be serious agricultural pests. Among the native fauna degus
(Octodon) and hog-nosed skunk
s (Conepatus) are important prey, but mammals as formidable as a Gray Fox
(Urocyon cinereoargenteus) – two to over three times as heavy as the birds and certainly not defenceless – are occasionally hunted and killed by this hawk. Its diet is rounded off with an occasional bird – including carnivorous species like the Burrowing Owl
(Athene cunicularia) and sizeable prey such as Penelope
guan
s or the Chilean Tinamou
(Nothoprocta perdicaria) –, large squamate
s, and if need be also arthropod
s and carrion
. While not aggressive under normal circumstances, the Black-chested Eagle-buzzard will fiercely attack humans if it considers itself or its offspring threatened. It is near the top of the avian food chain in its range, in part since it is the only Andean
eagle found outside forest habitats. It may compete for carrion with the much larger Andean Condor
.
It nests in high trees or on rocky cliffs, or if these are not available on high trees or even cacti
. If no appropriate high place is available this species will nest in bushes or even on the ground. In Ecuador
, nesting can be observed all year round; elsewhere it might have a more restricted breeding season but information is scant and somewhat contradictory. The nest is a huge mass of sticks about 85 centimetres (33.5 in) in diameter; the Black-chested Buzzard-Eagle is just as likely to reuse an existing nest as to build a new one, and several abandoned nests are often found in the vicinity of an active one. The male and female engage in courtship flights, and copulate over a prolonged time of several weeks as the pairs bond. Little is known of the actual nesting; the clutch
contains usually but sometimes 1 or 3 eggs, which are incubated for about a month. The nestlings presumably are covered in white down
like in its relatives.
Due to its wide overall range it is considered a Species of Least Concern
by the IUCN. While it is rare and declining in places – e.g. in Rio Grande do Sul
and Santa Catarina state
s in Brazil
, or in parts of Argentina
– its habitat
requirements mean that it will to some degree benefit from deforestation
and it has for example colonized regions of the former Mata Atlântica forest in Alagoas
. The declines in Argentina have been attributed to poisoning by strychnine
baits deployed by sheep farmers trying to eradicate pests.
Bird of prey
Birds of prey are birds that hunt for food primarily on the wing, using their keen senses, especially vision. They are defined as birds that primarily hunt vertebrates, including other birds. Their talons and beaks tend to be relatively large, powerful and adapted for tearing and/or piercing flesh....
of the hawk
Hawk
The term hawk can be used in several ways:* In strict usage in Australia and Africa, to mean any of the species in the subfamily Accipitrinae, which comprises the genera Accipiter, Micronisus, Melierax, Urotriorchis and Megatriorchis. The large and widespread Accipiter genus includes goshawks,...
and eagle
Eagle
Eagles are members of the bird family Accipitridae, and belong to several genera which are not necessarily closely related to each other. Most of the more than 60 species occur in Eurasia and Africa. Outside this area, just two species can be found in the United States and Canada, nine more in...
family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
(Accipitridae
Accipitridae
The Accipitridae, one of the two major families within the order Accipitriformes , are a family of small to large birds with strongly hooked bills and variable morphology based on diet. They feed on a range of prey items from insects to medium-sized mammals, with a number feeding on carrion and a...
). It lives in open regions of South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
. This species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
is also known as the Black Buzzard-eagle, Grey Buzzard-eagle or analogously with "eagle" or "eagle-buzzard" replacing "buzzard-eagle", or as the Chilean Blue Eagle. It is sometimes placed in the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Buteo
Buteo
Buteo is a genus of medium to fairly large, wide-ranging raptors with a robust body and broad wings. In the Old World, members of this genus are called "buzzards", but "hawk" is used in North America...
.
Description
Buzzard
A buzzard is one of several large birds, but there are a number of meanings as detailed below.-Old World:In the Old World Buzzard can mean:* One of several medium-sized, wide-ranging raptors with a robust body and broad wings....
" ("hawk" in American terminology). It has a total length of 24-32 in (about 60–80 cm) and a wingspan of 58-79 in (149–200 cm). In the smaller G. m. australis subspecies, the weight is 3.7-7.1 lb. (1.7-3.2 kg), with no reported weights on the nominate subspecies. It is noted for its bulky, powerful-looking build. It is rather long- and broad-winged and the slightly tapering tail is short by comparison and colored black, with grey tips in fresh plumage. When perched, the wings cover the tail almost completely, giving the bird a unique near-tailess appearance when perched. The adult has a white underside, sometimes with fine blackish stripes; its upperparts are dark grey with a blackish, brownish or bluish hue. The feathers of the neck and the lowest dark feathers of the breast are somewhat elongated. Adults have an ash-grey-and-white zone on the wings, the silvery white seen clearly from afar. The female is distinguished by a reddish-cinnamon hue to the upper- and underwing secondaries and is considerably larger than the male.
The immature plumage
Plumage
Plumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...
is reminiscent of that of the Great Black Hawk
Great Black Hawk
The Great Black Hawk, Buteogallus urubitinga, is a bird of prey in the family Accipitridae, which also includes the eagles, hawks and Old World vultures....
(Buteogallus urubitinga). Its upperparts are deep brown, sometimes almost black, and it has no light wing patch. The underside is white or light buff
Buff (colour)
Buff is a pale yellow-brown colour that got its name from the colour of buff leather.Displayed on the right is the colour buff.EtymologyAccording to the Oxford English Dictionary, buff as a descriptor of a colour was first used in the London Gazette of 1686, describing a uniform to be "A Red Coat...
with heavy dark streaks on the breast and dark bars on the belly and thighs. It does not acquire the full adult plumage until 4–5 years old.
It is not very vocal, calling usually in flight and when close to the nest
Nest
A nest is a place of refuge to hold an animal's eggs or provide a place to live or raise offspring. They are usually made of some organic material such as twigs, grass, and leaves; or may simply be a depression in the ground, or a hole in a tree, rock or building...
. Some calls resemble a wild human laugh, others are a curlew
Curlew
The curlews , genus Numenius, are a group of eight species of birds, characterised by long, slender, downcurved bills and mottled brown plumage. They are one of the most ancient lineages of scolopacid waders, together with the godwits which look similar but have straight bills...
-like whistle. Occasionally flying birds give a high-pitched vocalization "kukukukuku".
The Black-chested Buzzard-Eagle is readily identified in flight by its short wedge-shaped tail scarcely protruding from its long, broad wings
Bird flight
Flight is the main mode of locomotion used by most of the world's bird species. Flight assists birds while feeding, breeding and avoiding predators....
. It is usually easy to make out the generally white underparts with the dark chest-band and tail if the birds are adult. Yet as this bird is usually encountered in the wild when it soars, you are less likely to see its grey upperparts.
Taxonomy and systematics
Its scientific nameBinomial nomenclature
Binomial nomenclature is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages...
is Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
ized Ancient Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
and means "black-and-white crane-eagle" or (if called Buteo melanoleucos) "black-and-white buzzard": Geranoaetus comes from Ancient Greek géranos (γέρανoς), "crane
Crane (bird)
Cranes are a family, Gruidae, of large, long-legged and long-necked birds in the order Gruiformes. There are fifteen species of crane in four genera. Unlike the similar-looking but unrelated herons, cranes fly with necks outstretched, not pulled back...
" + aetós (ἆετός), "eagle". The "crane" reference is due to its grey upper wings and its loud cries. The alternative genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
name Buteo is simply the Latin term used for these hawks in Ancient Rome
Ancient Rome
Ancient Rome was a thriving civilization that grew on the Italian Peninsula as early as the 8th century BC. Located along the Mediterranean Sea and centered on the city of Rome, it expanded to one of the largest empires in the ancient world....
, translating as "buzzard" (in the European sense). melanoleucus is from Ancient Greek mélan- (μέλαν-), "black-" + leukós (λευκός), "white". This refers to the contrasting coloration when seen from below.
When the Black-chested Buzzard-Eagle was first described by Louis Jean Pierre Vieillot
Louis Jean Pierre Vieillot
Louis Jean Pierre Vieillot was a French ornithologist.Vieillot described a large number of birds for the first time, especially those he encountered during the time he spent in the West Indies and North America, and 26 genera established by him are still in use...
in 1819, it was placed in the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Spizaetus
Spizaetus
Spizaetus is the typical hawk-eagle birds of prey genus found in the tropics of the Americas. It was however used to indicate a group of tropical eagles that included species occurring in southern and southeastern Asia and one representative of this genus in the rainforests of West Africa. The Old...
, as Spizaetus melanoleucus. Today however, the monotypic genus Spizastur is merged in Spizaetus, and the Black-and-white Hawk-Eagle
Black-and-white Hawk-eagle
The Black-and-white Hawk-Eagle is a bird of prey species in the eagle and hawk family...
, originally described as by Vieillot three years earlier as Buteo melanoleucus, is now known as Spizaetus melanoleucus. The earlier use of the specific epithet melanoleucus for the Black-and-white Hawk-Eagle technically precludes its use for the Black-chested Buzzard-Eagle, except when it is placed in Geranoaetus. In fact, in the mid-20th century Buteo fuscescens was the prevailing name for the Black-chested Buzzard-Eagle for some years, but it was eventually dismissed as erroneous. This specific name was established – as Spizaetus fuscescens – by Vieillot for the immature of the Black-chested Buzzard-Eagle at the very same time as he described the adult, because he could not believe that such differently-colored birds were conspecific
Conspecificity
Conspecificity is a concept in biology. Two or more individual organisms, populations, or taxa are conspecific if they belong to the same species....
.
As the two birds are not placed in the same genus today, Article 59.3 of the ICZN
International Commission on Zoological Nomenclature
The International Commission on Zoological Nomenclature is an organization dedicated to "achieving stability and sense in the scientific naming of animals". Founded in 1895, it currently comprises 28 members from 20 countries, mainly practicing zoological taxonomists...
Code applies. According to this, a junior homonym replaced before 1961 is not rendered permanently invalid (as junior homonyms usually are) if "the substitute name is not in use" – which has been the case after Amadon's 1963 revision. Hence, in this case the scientific name Buteo melanoleucus can apply, even though the Black-and-white Hawk-Eagle was earlier described under exactly that name, while the senior homonym melanoleucus still applies to the latter species when placed in Spizaetus according to the usual ICZN rules. Consequently, the proper name to use for each bird has through a number of coincidences become the one the other species was described under.
Systematics
There are two subspeciesSubspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
:
- Eastern Black-chested Buzzard-Eagle, Geranoaetus melanoleucus melanoleucos (Vieillot, 1819) – SE South America from S and E BrazilBrazilBrazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
(AlagoasAlagoasAlagoas is one of the 27 federative units of Brazil and is situated in the eastern part of the Northeast Region. It borders: Pernambuco ; Sergipe ; Bahia ; and the Atlantic Ocean . It occupies an area of 27,767 km², being slightly larger than Haiti...
, Rio de JaneiroRio de Janeiro (state)Rio de Janeiro is one of the 27 states of Brazil.Rio de Janeiro has the second largest economy of Brazil behind only São Paulo state.The state of Rio de Janeiro is located within the Brazilian geopolitical region classified as the Southeast...
, and São Paulo stateSão Paulo (state)São Paulo is a state in Brazil. It is the major industrial and economic powerhouse of the Brazilian economy. Named after Saint Paul, São Paulo has the largest population, industrial complex, and economic production in the country. It is the richest state in Brazil...
s) through ParaguayParaguayParaguay , officially the Republic of Paraguay , is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to the east and northeast, and Bolivia to the northwest. Paraguay lies on both banks of the Paraguay River, which runs through the center of the...
, UruguayUruguayUruguay ,officially the Oriental Republic of Uruguay,sometimes the Eastern Republic of Uruguay; ) is a country in the southeastern part of South America. It is home to some 3.5 million people, of whom 1.8 million live in the capital Montevideo and its metropolitan area...
, and NE ArgentinaArgentinaArgentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
- Larger, Plain white below.
- Western Black-chested Buzzard-Eagle, Geranoaetus melanoleucus australis Swann, 1922 – AndesAndesThe Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...
from NW VenezuelaVenezuelaVenezuela , officially called the Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It borders Colombia to the west, Guyana to the east, and Brazil to the south...
(MéridaMérida (state)Mérida State is one of the 23 states of Venezuela. The state capital is Mérida.Mérida State covers a total surface area of 11,300 km² and, in 2007, had an estimated population of 843,800.- Climate and Vegetation :...
) through ColombiaColombiaColombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
(Cordillera CentralCordillera Central, ColombiaThe Cordillera Central range is one of the three branches of ridges in the Andes Mountains that split in southern Colombia towards the north up to the Montes de Maria....
, occasionally ranging into the Cordillera Occidental), EcuadorEcuadorEcuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...
, PeruPeruPeru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
, BoliviaBoliviaBolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...
, ChileChileChile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
, and W Argentina to Tierra del FuegoTierra del FuegoTierra del Fuego is an archipelago off the southernmost tip of the South American mainland, across the Strait of Magellan. The archipelago consists of a main island Isla Grande de Tierra del Fuego divided between Chile and Argentina with an area of , and a group of smaller islands including Cape...
- Western Black-chested Buzzard-Eagle, Geranoaetus melanoleucus australis Swann, 1922 – Andes
- Smaller. White with fine dark barring below.
The Black-chested Buzzard-Eagle is allied to the Buteo
Buteo
Buteo is a genus of medium to fairly large, wide-ranging raptors with a robust body and broad wings. In the Old World, members of this genus are called "buzzards", but "hawk" is used in North America...
hawks, and it is sometimes included with these. Other authors place it in the monotypic genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Geranoaetus. Though the former seems to be more appropriate from a phylogenetic
Phylogenetics
In biology, phylogenetics is the study of evolutionary relatedness among groups of organisms , which is discovered through molecular sequencing data and morphological data matrices...
standpoint, the latter is still used here, as much more research into phylogeny and hybridization has to take place before the correct taxonomy
Taxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
of the buteonine
Buteoninae
Buteoninae is a bird of prey subfamily which consists of medium to large broad-winged species.They have large powerful hooked beaks for tearing flesh from their prey, strong legs and powerful talons...
s can be resolved. It stands to note that the taxonomic and systematic dispute goes back to the early-mid 20th century already. However, it seems there is no real reason to suppose that the lineage of the Black-chested Buzzard-Eagle is North American in origin; fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s that might have been its ancestors at first sight differ in details and are more likely to belong to other buteonine lineages. Due to this species buteonine lineage, this species and the closely related Harpyhaliaetus
Harpyhaliaetus
Harpyhaliaetus is a genus of eagles. Recent studies have shown that the Solitary Eagle is closely related to the black-hawks, in particular the Savanna Hawk which is smaller and browner but otherwise very similar to "Harpyhaliaetus"...
are not considered "true eagles", as are Aquila
Aquila
Aquila is the Latin and Romance language word for eagle and may also refer to:-Signs and symbols:* Aquila , a Roman military standard* Latin name for the Eagle -Places:...
eagles and "hawk-eagle
Spizaetus
Spizaetus is the typical hawk-eagle birds of prey genus found in the tropics of the Americas. It was however used to indicate a group of tropical eagles that included species occurring in southern and southeastern Asia and one representative of this genus in the rainforests of West Africa. The Old...
s", and are thus the largest extant type of the diverse buteonine lineage.
This species could be close to the White-tailed Hawk
White-tailed Hawk
The White-tailed Hawk is a large bird of prey species found in tropical or subtropical environments across the Americas.-Description:...
(Buteo albicaudatus), and perhaps to the Grey-backed
Grey-backed Hawk
The Grey-backed Hawk is a species of bird of prey in the Accipitridae family.It is found in Ecuador and Peru.Its natural habitats are subtropical or tropical dry forests and subtropical or tropical moist lowland forests....
(Leucopternis occidentalis), White
White Hawk
The White Hawk , a bird of prey breeding in the tropical New World, belongs to the family Accipitridae of the Falconiformes; it is sometimes separated in the Accipitriformes with the other hawks and their relatives...
(L. albicollis), and Mantled Hawk
Mantled Hawk
The Mantled Hawk is a species of bird of prey in the Accipitridae family.It is found in Brazil, Paraguay, and Uruguay. Its natural habitat is subtropical or tropical moist lowland forests. It is becoming rare due to habitat loss.-References:* BirdLife International 2004. . Downloaded on 24...
s (L. polionotus) which it resembles in habitus
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
except for being larger. Its closest living relatives may well be the Red-backed (B. polyosoma) and Puna Hawks (B. poecilochrous). Particularly some populations of the former look like small Black-chested Buzzard-Eagles. The Barred Hawk
Barred Hawk
The Barred Hawk is a species of bird of prey in the Accipitridae family. It has also been known as the Black-chested Hawk....
(L. princeps) looks similar to the Black-chested Buzzard-Eagle in general color pattern, though the tail differs much in shape, size, and the bright white central band stands out.
The relationship of the Black-chested Buzzard-Eagle to the prehistoric
Prehistory
Prehistory is the span of time before recorded history. Prehistory can refer to the period of human existence before the availability of those written records with which recorded history begins. More broadly, it refers to all the time preceding human existence and the invention of writing...
genera Titanohierax from the Caribbean
Caribbean
The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...
and the Pan-American Amplibuteo also warrant more study. The crab-hawks (Buteogallus
Buteogallus
Buteogallus is a genus of bird of prey in the family Accipitridae. All members of this genus are essentially Neotropical, but the distribution of a single species extends slightly into extreme southern USA. Most are known as black-hawks or mangrove-hawks...
) and the solitary "eagles" (Harpyhaliaetus
Harpyhaliaetus
Harpyhaliaetus is a genus of eagles. Recent studies have shown that the Solitary Eagle is closely related to the black-hawks, in particular the Savanna Hawk which is smaller and browner but otherwise very similar to "Harpyhaliaetus"...
) seem to be allied with the latter, to the extent that these three genera might be united in Buteogallus. That genus in the present restricted sense contains species also quite similar in habitus and size to the Black-chested Eagle-buzzard.
Fossil record
Some fossilFossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s have been placed in Geranoaetus, but those from North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
have since been moved elsewhere:
- "Geranoaetus" ales, "G." contortus and "G." conterminus are now in Buteo.
- "Geranoaetus" fragilis (Fragile "Eagle") and "G." milleri (Miller's "Eagle") are now in Buteogallus. The type specimenBiological typeIn biology, a type is one particular specimen of an organism to which the scientific name of that organism is formally attached...
s of the latter were at first erroneously believed to be of the Black-chested Eagle-buzzard. - "Geranoaetus" grinnelli (Grinnell's "Eagle") is now in SpizaetusSpizaetusSpizaetus is the typical hawk-eagle birds of prey genus found in the tropics of the Americas. It was however used to indicate a group of tropical eagles that included species occurring in southern and southeastern Asia and one representative of this genus in the rainforests of West Africa. The Old...
. - "Geranoaetus" dananus, originally described as "Aquila" danana, is of rather unclear affiliations but probably belongs to the same lineage as the above.
Bones indistinguishable from those of living Black-chested Buzzard-Eagles were found in a spring deposit at the Baños de Ciego Montero in Cienfuegos Province
Cienfuegos Province
Cienfuegos is one of the provinces of Cuba. The capital city of the province is also called Cienfuegos and was founded by French settlers in 1819....
, Cuba
Cuba
The Republic of Cuba is an island nation in the Caribbean. The nation of Cuba consists of the main island of Cuba, the Isla de la Juventud, and several archipelagos. Havana is the largest city in Cuba and the country's capital. Santiago de Cuba is the second largest city...
. A partial left carpometacarpus
Carpometacarpus
The carpometacarpus is the fusion of the carpal and metacarpal bone, essentially a single fused bone between the wrist and the knuckles. It is a smallish bone in most birds, generally flattened and with a large hole in the middle. In flightless birds, however, its shape may be slightly different,...
– Specimen AMNH
American Museum of Natural History
The American Museum of Natural History , located on the Upper West Side of Manhattan in New York City, United States, is one of the largest and most celebrated museums in the world...
FR 6190 – as well as a fingerbone probably date from some time in the Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
, during the last ice age
Quaternary glaciation
Quaternary glaciation, also known as the Pleistocene glaciation, the current ice age or simply the ice age, refers to the period of the last few million years in which permanent ice sheets were established in Antarctica and perhaps Greenland, and fluctuating ice sheets have occurred elsewhere...
. Its contemporary close relatives on Cuba, as far as it is known, consisted of the gigantic eagle-like buteonine
Buteoninae
Buteoninae is a bird of prey subfamily which consists of medium to large broad-winged species.They have large powerful hooked beaks for tearing flesh from their prey, strong legs and powerful talons...
hawks which were clearly distinct by size alone, while the Pleistocene record of similar-sized birds from continental North America is from the far west.
Ecology
The Black-chested Buzzard-Eagle is found in mountainous or hilly terrainTerrain
Terrain, or land relief, is the vertical and horizontal dimension of land surface. When relief is described underwater, the term bathymetry is used...
with sparse vegetation, shrubland or (in the south of its range) Nothofagus
Nothofagus
Nothofagus, also known as the southern beeches, is a genus of 35 species of trees and shrubs native to the temperate oceanic to tropical Southern Hemisphere in southern South America and Australasia...
forest, where it spends a lot of time soaring
Bird flight
Flight is the main mode of locomotion used by most of the world's bird species. Flight assists birds while feeding, breeding and avoiding predators....
in thermal
Thermal
A thermal column is a column of rising air in the lower altitudes of the Earth's atmosphere. Thermals are created by the uneven heating of the Earth's surface from solar radiation, and are an example of convection. The sun warms the ground, which in turn warms the air directly above it...
s and vertical draft
Vertical draft
An updraft or downdraft is the vertical movement of air as a weather related phenomenon. One of two forces causes the air to move. Localized regions of warm or cool air will exhibit vertical movement. A mass of warm air will typically be less dense than the surrounding region, and so will rise...
s while looking for prey
Predation
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...
. It requires large territories with suitable habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
, the páramo
Páramo
The term páramo can refer to a variety of ecosystems. Some ecologists describe the páramo broadly as “all high, tropical, montane vegetation above the continuous timberline”. A more narrow term classifies the páramo according to its regional placement - specifically located in “the northern Andes...
s at the north of its range, for example, while providing the latter, fail to provide the former, and thus it has only been recorded in the largest patches of such habitat, such as Páramo de Frontino. Most common between about 5000 feet (1,524 m) and 15000 feet (4,572 m) ASL
Above mean sea level
The term above mean sea level refers to the elevation or altitude of any object, relative to the average sea level datum. AMSL is used extensively in radio by engineers to determine the coverage area a station will be able to reach...
, it rarely ventures into the lowlands.
It is most conspicuous in the mid-morning and afternoon, when individuals will seek out places which provide the best soaring conditions, such as north and west facing slopes and ridges. Apparently, their main interest at these times is aerial play and display; they tend to ignore places where food is more plentiful or easily hunted in favor of simply soaring alone or in pairs in strong air currents.
The food of this carnivore
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...
consists mainly of mid-sized mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s; the introduced European Rabbit
European Rabbit
The European Rabbit or Common Rabbit is a species of rabbit native to south west Europe and north west Africa . It has been widely introduced elsewhere often with devastating effects on local biodiversity...
(Oryctolagus cuniculus) seems to have become a key prey item. The Black-chested Buzzard-Eagle is helpful to farmers by keeping down the numbers of the rabbits, which can be serious agricultural pests. Among the native fauna degus
Octodon
Octodon is a genus of octodontid rodents, of which the best-known member is the degu O. degus. The full list of species is:* O. bridgesi, Bridge's Degu, found in Argentina and Chile...
(Octodon) and hog-nosed skunk
Hog-nosed skunk
The hog-nosed skunks belong to the genus Conepatus and are members of the family Mephitidae . They are native to the Americas. They have white backs and tails and black underparts...
s (Conepatus) are important prey, but mammals as formidable as a Gray Fox
Gray Fox
The gray fox is a mammal of the order Carnivora ranging throughout most of the southern half of North America from southern Canada to the northern part of South America...
(Urocyon cinereoargenteus) – two to over three times as heavy as the birds and certainly not defenceless – are occasionally hunted and killed by this hawk. Its diet is rounded off with an occasional bird – including carnivorous species like the Burrowing Owl
Burrowing Owl
The Burrowing Owl is a tiny but long-legged owl found throughout open landscapes of North and South America. Burrowing Owls can be found in grasslands, rangelands, agricultural areas, deserts, or any other open dry area with low vegetation. They nest and roost in burrows, such as those excavated...
(Athene cunicularia) and sizeable prey such as Penelope
Penelope (genus)
Penelope is a bird genus in the Cracidae family consisting of a number of large turkey-like arboreal species, the typical guans. The range of these species is in forests from southern Mexico to tropical South America. These largish birds have predominately brown plumage and have relatively small...
guan
Guan (bird)
The guans are a number of bird genera which make up the largest group in the family Cracidae. They are found mainly in northern South America, southern Central America, and a few adjacent Caribbean islands...
s or the Chilean Tinamou
Chilean Tinamou
The Chilean Tinamou, Nothoprocta perdicaria, is a type of tinamou commonly found in high altitude shrubland in subtropical regions of central Chile.-Etymology:...
(Nothoprocta perdicaria) –, large squamate
Squamata
Squamata, or the scaled reptiles, is the largest recent order of reptiles, including lizards and snakes. Members of the order are distinguished by their skins, which bear horny scales or shields. They also possess movable quadrate bones, making it possible to move the upper jaw relative to the...
s, and if need be also arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
s and carrion
Carrion
Carrion refers to the carcass of a dead animal. Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters include vultures, hawks, eagles, hyenas, Virginia Opossum, Tasmanian Devils, coyotes, Komodo dragons, and burying beetles...
. While not aggressive under normal circumstances, the Black-chested Eagle-buzzard will fiercely attack humans if it considers itself or its offspring threatened. It is near the top of the avian food chain in its range, in part since it is the only Andean
Andes
The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...
eagle found outside forest habitats. It may compete for carrion with the much larger Andean Condor
Andean Condor
The Andean Condor is a species of South American bird in the New World vulture family Cathartidae and is the only member of the genus Vultur...
.
It nests in high trees or on rocky cliffs, or if these are not available on high trees or even cacti
Cactus
A cactus is a member of the plant family Cactaceae. Their distinctive appearance is a result of adaptations to conserve water in dry and/or hot environments. In most species, the stem has evolved to become photosynthetic and succulent, while the leaves have evolved into spines...
. If no appropriate high place is available this species will nest in bushes or even on the ground. In Ecuador
Ecuador
Ecuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...
, nesting can be observed all year round; elsewhere it might have a more restricted breeding season but information is scant and somewhat contradictory. The nest is a huge mass of sticks about 85 centimetres (33.5 in) in diameter; the Black-chested Buzzard-Eagle is just as likely to reuse an existing nest as to build a new one, and several abandoned nests are often found in the vicinity of an active one. The male and female engage in courtship flights, and copulate over a prolonged time of several weeks as the pairs bond. Little is known of the actual nesting; the clutch
Clutch (eggs)
A clutch of eggs refers to all the eggs produced by birds or reptiles, often at a single time, particularly those laid in a nest.In birds, destruction of a clutch by predators, , results in double-clutching...
contains usually but sometimes 1 or 3 eggs, which are incubated for about a month. The nestlings presumably are covered in white down
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 and padding, used in goods such as jackets, bedding,...
like in its relatives.
Due to its wide overall range it is considered a Species of Least Concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
by the IUCN. While it is rare and declining in places – e.g. in Rio Grande do Sul
Rio Grande do Sul
Rio Grande do Sul is the southernmost state in Brazil, and the state with the fifth highest Human Development Index in the country. In this state is located the southernmost city in the country, Chuí, on the border with Uruguay. In the region of Bento Gonçalves and Caxias do Sul, the largest wine...
and Santa Catarina state
Santa Catarina (state)
Santa Catarina is a state in southern Brazil with one of the highest standards of living in Latin America. Its capital is Florianópolis, which mostly lies on the Santa Catarina Island. Neighbouring states are Rio Grande do Sul to the south and Paraná to the north. It is bounded on the east by...
s in Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
, or in parts of Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
– its habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
requirements mean that it will to some degree benefit from deforestation
Deforestation
Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use....
and it has for example colonized regions of the former Mata Atlântica forest in Alagoas
Alagoas
Alagoas is one of the 27 federative units of Brazil and is situated in the eastern part of the Northeast Region. It borders: Pernambuco ; Sergipe ; Bahia ; and the Atlantic Ocean . It occupies an area of 27,767 km², being slightly larger than Haiti...
. The declines in Argentina have been attributed to poisoning by strychnine
Strychnine
Strychnine is a highly toxic , colorless crystalline alkaloid used as a pesticide, particularly for killing small vertebrates such as birds and rodents. Strychnine causes muscular convulsions and eventually death through asphyxia or sheer exhaustion...
baits deployed by sheep farmers trying to eradicate pests.