Darwin's Rhea
Encyclopedia
Darwin's Rhea, Rhea pennata, also known as the Lesser Rhea, is a large flightless bird
, but the smaller of the two extant species of rheas
. It is found in the Altiplano
and Patagonia
in South America
.
s, enabling it to run particularly well. It can reach speeds of 60 km/h (37 mph), enabling it to outrun predators. The sharp claws on the toes are effective weapons. Their plumage is spotted brown and white, and the upper part of their tarsus
is feathered.
, a Greek goddess, and pennata means winged. The specific name was bestowed in 1834 by Darwin
's contemporary and rival Alcide d'Orbigny
who first described the bird to Europeans, from a specimen from the lower Río Negro south of Buenos Aires
, Argentina
. As late as 2008 it was classified in the monotypic
genus Pterocnemia. This word is formed from two Greek words pteron meaning feathers, and knēmē meaning the leg between the knee and the ankle, hence feather-legged, alluding to their feathers that cover the top part of the leg. In 2008 the SACC
subsumed Pterocnemia into the genus Rhea
.
:
It has been suggested that the two northern taxa R. p. tarapacensis and R. p. garleppi should be considered a separate species, the Puna Rhea (R. tarapacensis, with garleppi as a subspecies). Both garleppi and tarapacensis were described by Charles Chubb in 1913. It is possible garleppi should be considered a junior synonym of tarapacensis.
plateau (the Altiplano
), through the countries of Argentina
, Bolivia
, Chile
, and Peru
. It is known locally by various names, depending on the location: For example suri, choique, ñandú petiso, or ñandú del norte. The name 'ñandú' comes from the bird's name in Guaraní
ñandú guazu, meaning big spider, posibly in relation to their habit of opening and lowering alternatively wings when they run. All subspecies prefer grasslands, brushlands and marshland. However the nominate subspecies prefers elevations less than 1500 m (4,921.3 ft), where the other subspecies typically range from 3000 to 4500 m (9,842.5 to 14,763.8 ft), but locally down to 1500 m (4,921.3 ft) in the south.
During the second voyage of HMS Beagle, the young naturalist Charles Darwin
made many trips on land, and around August 1833 heard from gaucho
s in the Río Negro area of Northern Patagonia about the existence of a smaller Rhea, "a very rare bird which they called the Avestruz Petise". He continued searching fruitlessly for this bird, and the Beagle sailed south, putting in at Port Desire
in southern Patagonia on 23 December. On the following day Darwin shot a guanaco which provided them with a Christmas meal, and in the first days of January, the artist Conrad Martens
shot a rhea which they enjoyed eating before Darwin realised that this was the elusive smaller rhea rather than a juvenile, and preserved the head, neck, legs, one wing, and many of the larger feathers. As with his other collections, these were sent to John Stevens Henslow
in Cambridge. On 26 January they entered the Straits of Magellan and at St. Gregory's Bay Darwin met Patagonians he described as "excellent practical naturalists". A half Indian who had been born in the Northern Provinces told him that the smaller rheas were the only species this far south, while the larger rheas kept to the north. On an expedition up the Santa Cruz River
they saw several of the smaller rheas, but they were too wary to be approached closely or caught.
In 1837 the Darwin's Rhea was described as Rhea darwinii (later synomized
with R. pennata) by the ornithologist John Gould
in a presentation to the Zoological Society of London
in which he was followed by Darwin reading a paper on the eggs and distribution of the two species of rheas.
When Gould classified the Darwin's Rhea and the Greater Rhea as separate species, he confirmed a serious problem for Darwin. These birds mainly live in different parts of Patagonia, but there is also an overlapping zone where the two species coexist. As every living being had been created in a fixed form, as accepted by the science of his time, they could only change their appearance by a perfect adaptation to their way of life, but would still be the same species. But now he had to deal with two different species. This started to form his idea that species were not fixed at all, but that another mechanism might be at work.
, with the primary threats being hunting, egg-collecting, and fragmentation of its habitat due to conversion to farmland or pastures for cattle-grazing. The total range is estimated at 1100000 km² (424,712.4 sq mi). The southern nominate subspecies remains relatively widespread and locally fairly common, but the situation for the two northern subspecies is more worrying, with their combined population estimated as being in the hundreds.
Flightless bird
Flightless birds are birds which lack the ability to fly, relying instead on their ability to run or swim. They are thought to have evolved from flying ancestors. There are about forty species in existence today, the best known being the ostrich, emu, cassowary, rhea, kiwi, and penguin...
, but the smaller of the two extant species of rheas
Rhea (bird)
The rheas are ratites in the genus Rhea, native to South America. There are two existing species: the Greater or American Rhea and the Lesser or Darwin's Rhea. The genus name was given in 1752 by Paul Möhring and adopted as the English common name. Möhring's reason for choosing this name, from the...
. It is found in the Altiplano
Altiplano
The Altiplano , in west-central South America, where the Andes are at their widest, is the most extensive area of high plateau on Earth outside of Tibet...
and Patagonia
Patagonia
Patagonia is a region located in Argentina and Chile, integrating the southernmost section of the Andes mountains to the southwest towards the Pacific ocean and from the east of the cordillera to the valleys it follows south through Colorado River towards Carmen de Patagones in the Atlantic Ocean...
in 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...
.
Description
It stands at 90 to 100 cm (35.4 to 39.4 in) tall and weighs 15 to 25 kg (33.1 to 55.1 lb), and has larger wings than other ratiteRatite
A ratite is any of a diverse group of large, flightless birds of Gondwanan origin, most of them now extinct. Unlike other flightless birds, the ratites have no keel on their sternum—hence the name from the Latin ratis...
s, enabling it to run particularly well. It can reach speeds of 60 km/h (37 mph), enabling it to outrun predators. The sharp claws on the toes are effective weapons. Their plumage is spotted brown and white, and the upper part of their tarsus
Tarsus (skeleton)
In tetrapods, the tarsus is a cluster of articulating bones in each foot situated between the lower end of tibia and fibula of the lower leg and the metatarsus. In the foot the tarsus articulates with the bones of the metatarsus, which in turn articulate with the bones of the individual toes...
is feathered.
Etymology
Darwin's Rhea gets its scientific name from RheaRhea (mythology)
Rhea was the Titaness daughter of Uranus, the sky, and Gaia, the earth, in Greek mythology. She was known as "the mother of gods". In earlier traditions, she was strongly associated with Gaia and Cybele, the Great Goddess, and was later seen by the classical Greeks as the mother of the Olympian...
, a Greek goddess, and pennata means winged. The specific name was bestowed in 1834 by Darwin
Charles Darwin
Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...
's contemporary and rival Alcide d'Orbigny
Alcide d'Orbigny
Alcide Charles Victor Marie Dessalines d'Orbigny was a French naturalist who made major contributions in many areas, including zoology , palaeontology, geology, archaeology and anthropology....
who first described the bird to Europeans, from a specimen from the lower Río Negro south of Buenos Aires
Buenos Aires Province
The Province of Buenos Aires is the largest and most populous province of Argentina. It takes the name from the city of Buenos Aires, which used to be the provincial capital until it was federalized in 1880...
, 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...
. As late as 2008 it was classified in the monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
genus Pterocnemia. This word is formed from two Greek words pteron meaning feathers, and knēmē meaning the leg between the knee and the ankle, hence feather-legged, alluding to their feathers that cover the top part of the leg. In 2008 the SACC
American Ornithologists' Union
The American Ornithologists' Union is an ornithological organization in the USA. Unlike the National Audubon Society, its members are primarily professional ornithologists rather than amateur birders...
subsumed Pterocnemia into the genus Rhea
Rhea (bird)
The rheas are ratites in the genus Rhea, native to South America. There are two existing species: the Greater or American Rhea and the Lesser or Darwin's Rhea. The genus name was given in 1752 by Paul Möhring and adopted as the English common name. Möhring's reason for choosing this name, from the...
.
Taxonomy
There are three 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...
:
- R. p. garleppi is found in the punaPuna grasslandThe Puna grassland ecoregion, of the montane grasslands and shrublands biome, is found in the central Andes Mountains of South America. It is considered one of the eight Natural Regions in Peru, but extends south as far as northern Argentina and Chile....
of southeastern 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....
, southwestern BoliviaBoliviaBolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...
, and northwestern 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...
. - R. p. tarapacensis is found in the puna of northern 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...
from the region of Arica and Parinacota to AntofagastaAntofagasta RegionThe II Antofagasta Region is one of Chile's fifteen first-order administrative divisions. It comprises three provinces, Antofagasta, El Loa and Tocopilla...
. - R. p. pennata is found in the Patagonian steppes of Argentina and Chile.
It has been suggested that the two northern taxa R. p. tarapacensis and R. p. garleppi should be considered a separate species, the Puna Rhea (R. tarapacensis, with garleppi as a subspecies). Both garleppi and tarapacensis were described by Charles Chubb in 1913. It is possible garleppi should be considered a junior synonym of tarapacensis.
Behavior
The males of this species become aggressive once they are incubating eggs. The females thus lay the later eggs near the nest, rather than in it. Most of the eggs are moved into the nest by the male, but some remain outside, where they rot and attract flies. The male, and later the chicks, eat these flies. The incubation period is 30–44 days, and the clutch size is from 5–55 eggs. The eggs are 87 to 126 mm (3.4 to 5 in) and are greenish yellow. Outside the breeding season, Darwin's Rhea is quite sociable: it lives in groups of from 5 to 30 birds, of both sexes and a variety of ages.Distribution and habitat
Darwin's Rhea lives in areas of open scrub in the grasslands of Patagonia and on the AndeanAndes
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...
plateau (the Altiplano
Altiplano
The Altiplano , in west-central South America, where the Andes are at their widest, is the most extensive area of high plateau on Earth outside of Tibet...
), through the countries 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...
, Bolivia
Bolivia
Bolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...
, Chile
Chile
Chile ,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 Peru
Peru
Peru , 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....
. It is known locally by various names, depending on the location: For example suri, choique, ñandú petiso, or ñandú del norte. The name 'ñandú' comes from the bird's name in Guaraní
Guaraní language
Guaraní, specifically the primary variety known as Paraguayan Guaraní , is an indigenous language of South America that belongs to the Tupí–Guaraní subfamily of the Tupian languages. It is one of the official languages of Paraguay , where it is spoken by the majority of the population, and half of...
ñandú guazu, meaning big spider, posibly in relation to their habit of opening and lowering alternatively wings when they run. All subspecies prefer grasslands, brushlands and marshland. However the nominate subspecies prefers elevations less than 1500 m (4,921.3 ft), where the other subspecies typically range from 3000 to 4500 m (9,842.5 to 14,763.8 ft), but locally down to 1500 m (4,921.3 ft) in the south.
History of the discovery of the genus Rhea
Charles Darwin
Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...
made many trips on land, and around August 1833 heard from gaucho
Gaucho
Gaucho is a term commonly used to describe residents of the South American pampas, chacos, or Patagonian grasslands, found principally in parts of Argentina, Uruguay, Southern Chile, and Southern Brazil...
s in the Río Negro area of Northern Patagonia about the existence of a smaller Rhea, "a very rare bird which they called the Avestruz Petise". He continued searching fruitlessly for this bird, and the Beagle sailed south, putting in at Port Desire
Puerto Deseado
Puerto Deseado, originally called Port Desire, is a city of about 15,000 inhabitants and a fishing port in Patagonia in Santa Cruz Province of Argentina, on the estuary of the Deseado River....
in southern Patagonia on 23 December. On the following day Darwin shot a guanaco which provided them with a Christmas meal, and in the first days of January, the artist Conrad Martens
Conrad Martens
Conrad Martens was an English-born landscape painter active in Australia from 1835.-Life and work:Conrad Martens' father was a merchant who came originally to London as Austrian Consul; Conrad was born in "Crutched Friars" near Tower Hill...
shot a rhea which they enjoyed eating before Darwin realised that this was the elusive smaller rhea rather than a juvenile, and preserved the head, neck, legs, one wing, and many of the larger feathers. As with his other collections, these were sent to John Stevens Henslow
John Stevens Henslow
John Stevens Henslow was an English clergyman, botanist and geologist. He is best remembered as friend and mentor to his pupil Charles Darwin.- Early life :...
in Cambridge. On 26 January they entered the Straits of Magellan and at St. Gregory's Bay Darwin met Patagonians he described as "excellent practical naturalists". A half Indian who had been born in the Northern Provinces told him that the smaller rheas were the only species this far south, while the larger rheas kept to the north. On an expedition up the Santa Cruz River
Santa Cruz River (Argentina)
Santa Cruz River is a river from the Argentine province of Santa Cruz.The Santa Cruz begins at the shore of the Viedma and Argentino Lakes, of glacial origin and located in the Los Glaciares National Park, and runs eastwards before reaching the Atlantic Coast, north of the southern tip of South...
they saw several of the smaller rheas, but they were too wary to be approached closely or caught.
In 1837 the Darwin's Rhea was described as Rhea darwinii (later synomized
Synonym (taxonomy)
In scientific nomenclature, a synonym is a scientific name that is or was used for a taxon of organisms that also goes by a different scientific name. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies...
with R. pennata) by the ornithologist John Gould
John Gould
John Gould was an English ornithologist and bird artist. The Gould League in Australia was named after him. His identification of the birds now nicknamed "Darwin's finches" played a role in the inception of Darwin's theory of evolution by natural selection...
in a presentation to the Zoological Society of London
Zoological Society of London
The Zoological Society of London is a charity devoted to the worldwide conservation of animals and their habitats...
in which he was followed by Darwin reading a paper on the eggs and distribution of the two species of rheas.
When Gould classified the Darwin's Rhea and the Greater Rhea as separate species, he confirmed a serious problem for Darwin. These birds mainly live in different parts of Patagonia, but there is also an overlapping zone where the two species coexist. As every living being had been created in a fixed form, as accepted by the science of his time, they could only change their appearance by a perfect adaptation to their way of life, but would still be the same species. But now he had to deal with two different species. This started to form his idea that species were not fixed at all, but that another mechanism might be at work.
Conservation
Darwin's Rhea is Near ThreatenedNear Threatened
Near Threatened is a conservation status assigned to species or lower taxa that may be considered threatened with extinction in the near future, although it does not currently qualify for the threatened status...
, with the primary threats being hunting, egg-collecting, and fragmentation of its habitat due to conversion to farmland or pastures for cattle-grazing. The total range is estimated at 1100000 km² (424,712.4 sq mi). The southern nominate subspecies remains relatively widespread and locally fairly common, but the situation for the two northern subspecies is more worrying, with their combined population estimated as being in the hundreds.