Darwin's rhea

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Darwin's rhea
At Zurich Zoo, Switzerland

Least Concern  (IUCN 3.1)[1]
CITES Appendix I (CITES)[2][note 1]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Infraclass: Palaeognathae
Order: Rheiformes
Family: Rheidae
Genus: Rhea
Species:
R. pennata
Binomial name
Rhea pennata
d'Orbigny, 1837
Subspecies
Synonyms
  • Pterocnemia pennata (d'Orbigny 1834) Chubb 1913
  • Rhea darwinii Gould 1837[4][5]
  • Pterocnemia darwinii (Gould 183)
  • Struthio darwinii (Gould 1837)
  • Rhea nana Lyddekker 1894

Darwin's rhea or the lesser rhea (Rhea pennata) is a large

extant species of rheas. It is found in the Altiplano and Patagonia in South America
.

Description

A family of Rhea pennata pennatas in the wild in Chile, 2006
Head of a Darwin's rhea at the Edinburgh Zoo

The lesser rhea stands at 90 to 100 cm (35–39 in) tall. Length is 92 to 100 cm (36–39 in) and weight is 15 to 28.6 kg (33–63 lb).[6][7] Like most ratites, it has a small head and a small bill, the latter measuring 6.2 to 9.2 cm (2.4 to 3.6 in), but has long legs and a long neck. It has relatively larger wings than other ratites, 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.[8] Their plumage is spotted brown and white, and the upper part of their tarsus is feathered.[6] The tarsus is 28 to 32 cm (11 to 13 in) long and has 18 horizontal plates on the front.[6]

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

SACC subsumed Pterocnemia into the genus Rhea.[11]

Taxonomy

Three subspecies have traditionally been recognized:

The IUCN considers the former two northern

junior synonym
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, roots, seeds, and leaves.[6][15] 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.[6]

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 87 to 126 mm (3.4–5.0 in) and are greenish yellow.[6] 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.[6]

Distribution and habitat

Darwin's rhea lives in areas of open scrub in the grasslands of Patagonia and on the

nominate subspecies prefers elevations less than 1,500 m (4,900 ft),[1] where the other subspecies typically range from 3,000 to 4,500 m (9,800–14,800 ft), but locally down to 1,220 m (4,000 ft) in the south.[14]

History of the discovery of the genus Rhea

Illustration of Darwin's rhea, published in 1841 in John Gould's description of birds collected on the second voyage of HMS Beagle

During 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.[16][17]

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.[18]

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.[19]

Conservation

Museum Wiesbaden, Germany

Darwin's rhea is categorized as

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.[14][6]

National Forest Corporation.[20]

Footnotes

  1. ^
    doi:10.2305/IUCN.UK.2018-2.RLTS.T22728199A132179491.en
    . Retrieved 19 November 2021.
  2. ^ "Appendices | CITES". cites.org. Retrieved 14 January 2022.
  3. ^ a b c Brands, S. (2008)
  4. ^ Peters, James L. (1979)
  5. ^ Gould, J. (1837). "On a New Rhea (Rhea Darwinii) from Mr. Darwin's Collection". Proceedings of the Zoological Society of London. 5 (51): 35.
  6. ^ a b c d e f g h i Davies, S.J.J.F. (2003)
  7. ^ Elliott, Andrew (1992)
  8. ^ Perrins, C. (1987)
  9. ^ Krulwich, R. (2009)
  10. ^ Gotch, A.T. (1995)
  11. ^ Nores, M. (2008)
  12. ^ a b Clements, J (2007)
  13. ^ a b Jaramillo et al. (2003)
  14. ^ a b c d Birdlife International (2016)
  15. ^ "Pterocnemia pennata (Lesser rhea)".
  16. ^ Barlow 1963, pp. 271–5.
  17. ^ Keynes 2001, pp. 212, 217–218
  18. ^ Darwin, C (1837)
  19. ^ Herbert, S (1980)
  20. ^
    Conaf
    (in Spanish). 11 May 2021. Retrieved 8 January 2022.
  21. ^ "Incendio en Parque Nacional Patagonia fue causado por "colapso" de estufa producto de fuertes vientos". Radio Cooperativa (in Spanish). 7 July 2021. Retrieved 12 January 2022.

Notes

  1. ^ Pterocnemia pennata pennata is included in Appendix II.

References

Wikimedia Commons has media related to Rhea pennata.
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