Оңтүстік Америка құсы – Дарвиннің суырқасы

Species of bird

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.

The lesser rhea stands at tall. Length is and weight is Like most ratites, it has a small head and a small bill, the latter measuring , 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. Their plumage is spotted brown and white, and the upper part of their tarsus is feathered. 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.

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. 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.

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 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. 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.

Darwin's rhea is categorized as least concern by the IUCN. The centre is run by Tompkins Conservation with the support of the National Forest Corporation.