Darwin's rhea or the lesser rhea (''Rhea pennata'') is a large
flightless bird, the smaller of the two
extant
Extant is the opposite of the word extinct. It may refer to:
* Extant hereditary titles
* Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English
* Extant taxon, a taxon which is not extinct, ...
species of
rheas
The rheas ( ), also known as ñandus ( ) or South American ostriches, are large ratites (flightless birds without a keel on their sternum bone) in the order Rheiformes, native to South America, distantly related to the ostrich and emu. Most taxo ...
. It is found in the
Altiplano and
Patagonia in
South America.
Description

The lesser rhea stands at tall. Length is and weight is .
Like most
ratite
A ratite () is any of a diverse group of flightless, large, long-necked, and long-legged birds of the infraclass Palaeognathae. Kiwi, the exception, are much smaller and shorter-legged and are the only nocturnal extant ratites.
The systematics ...
s, it has a small head and a small
bill
Bill(s) may refer to:
Common meanings
* Banknote, paper cash (especially in the United States)
* Bill (law), a proposed law put before a legislature
* Invoice, commercial document issued by a seller to a buyer
* Bill, a bird or animal's beak
Plac ...
, the latter measuring , but has long legs and a long neck. It has relatively larger wings than other
ratite
A ratite () is any of a diverse group of flightless, large, long-necked, and long-legged birds of the infraclass Palaeognathae. Kiwi, the exception, are much smaller and shorter-legged and are the only nocturnal extant ratites.
The systematics ...
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 feathers are similar to those of ostriches, in that they have no
aftershaft.
[Perrins, C. (1987)] Their plumage is spotted brown and white, and the upper part of their
tarsus is feathered.
The
tarsus is long and has 18 horizontal plates on the front.
Etymology
It is known as ''ñandú petiso'', or ''ñandú del norte'', in Argentina, where the majority live. Other names are ''suri'' and ''choique''. The name ''ñandú'' comes from the
greater rhea's name in
Guaraní, ''ñandu guazu'', meaning big spider, possibly in relation to their habit of alternately opening and lowering their wings when they run. In English, Darwin's rhea gets its
scientific name
In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...
from
Rhea, a Greek goddess, and ''pennata'', meaning winged. The
specific name Specific name may refer to:
* in Database management systems, a system-assigned name that is unique within a particular database
In taxonomy, either of these two meanings, each with its own set of rules:
* Specific name (botany), the two-part (bino ...
was bestowed in 1834 by
Darwin
Darwin may refer to:
Common meanings
* Charles Darwin (1809–1882), English naturalist and writer, best known as the originator of the theory of biological evolution by natural selection
* Darwin, Northern Territory, a territorial capital city i ...
'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.
[Davies, S.J.J.F. (2003)] 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''.
Taxonomy
Three
subspecies
In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...
have traditionally been recognized:
* ''R. p. garleppi'' is found in the
puna of southeastern
Peru, southwestern
Bolivia
, image_flag = Bandera de Bolivia (Estado).svg
, flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center
, flag_alt2 = 7 × 7 square p ...
, and northwestern
Argentina.
[Clements, J (2007)]
* ''R. p. pennata'' is found in the
Patagonian
Patagonia () refers to a geographical region that encompasses the southern end of South America, governed by Argentina and Chile. The region comprises the southern section of the Andes Mountains with lakes, fjords, temperate rainforests, and gl ...
steppes of Argentina and Chile.
The IUCN considers the former two northern
taxa ''R. p. tarapacensis'' and ''R. p. garleppi'' as a separate species, the puna rhea (''R. tarapacensis'').
[Jaramillo ''et al.'' (2003)] Both ''garleppi'' and ''tarapacensis'' were described by
Charles Chubb in 1913.
[Brands, S. (2008)] It is possible ''garleppi'' should be considered a
junior synonym
The Botanical and Zoological Codes of nomenclature treat the concept of synonymy differently.
* In botanical nomenclature, a synonym is a scientific name that applies to a taxon that (now) goes by a different scientific name. For example, Linna ...
of ''tarapacensis''.
Behavior
The lesser rhea is mainly a herbivore, with the odd small animal (lizards, beetles, grasshoppers) eaten on occasion. It predominately eats
saltbush and fruits from cacti, as well as grasses.
They tend to be quiet birds, except as chicks when they whistle mournfully, and as males looking for a female, when they emit a booming call.
The males of this species become aggressive once they are incubating eggs, even towards females. 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 and are greenish yellow.
Chicks mature by three years of age. 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
Andean plateau (the
Altiplano), through the countries of
Argentina,
Bolivia
, image_flag = Bandera de Bolivia (Estado).svg
, flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center
, flag_alt2 = 7 × 7 square p ...
,
Chile, and
Peru.
All subspecies prefer grasslands, brushlands and marshland. However, the
nominate subspecies
In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...
prefers elevations less than ,
where the other subspecies typically range from , but locally down to in the south.
[Birdlife International (2016)]
History of the discovery of the genus ''Rhea''

During the
second voyage of HMS ''Beagle'', the young naturalist
Charles Darwin made many trips on land, and around August 1833 heard from
gauchos 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, 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.
It was named ''Port Desire'' by the privateer Thomas C ...
in southern Patagonia on 23 December. On the following day, Darwin shot a
guanaco (similar to a
llama) 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 the ''Beagle'' 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, which were too wary to be approached closely or caught.
In 1837, Darwin's rhea was described as ''Rhea darwinii'' (later
synonymized 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.
[Darwin, C (1837)]
When Gould classified 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.
[Herbert, S (1980)]
Conservation

Darwin's rhea is categorized as
least concern by the
IUCN
The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...
.
The former southern nominate subspecies remains relatively widespread and locally fairly common. Its range is estimated at .
The situation for the two former northern subspecies is more worrying, with their combined population estimated as being possibly as low as in the hundreds.
However, they are classified as ''Rhea tarapacensis'' by the IUCN, which regards it as being
near threatened, with the primary threats being hunting, egg-collecting, and fragmentation of its habitat due to conversion to farmland or pastures for cattle-grazing.
Patagonia National Park in Chile's
Aysén Region hosts the Centro de Reproducción para la Conservación del Ñandú ('Reproduction Centre for Darwin's rhea Conservation').
The centre is run by Tompkins Conservation with the support of the
National Forest Corporation
The National Forest Corporation or CONAF (Corporación Nacional Forestal) is a Chilean private, non-profit organization, through which the Chilean state contributes to the development and sustainable management of the country's forest resources. C ...
.
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Footnotes
Notes
References
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{{Taxonbar, from=Q733120
Rheidae
Ratites
Domesticated birds
Flightless birds
Birds of the Altiplano
Birds of Patagonia
Birds of Argentina
Birds of Peru
Birds of Chile
Birds of Bolivia
Darwin's rhea
Darwin's rhea or the lesser rhea (''Rhea pennata'') is a large flightless bird, the smaller of the two extant species of rheas. It is found in the Altiplano and Patagonia in South America.
Description
The lesser rhea stands at tall. Length ...