Оңтүстік Америка құстары: Реалар (Rheas)

Genus of birds

Rheas (/'//r//iː//ə//z/ REEəz), also known as ñandus (/'//n//æ//n//d//uː//z/ NYANdooz) or South American ostrich, are moderately sized South American ratites (flightless birds without a keel on their sternum bone) of the order Rheiformes. They are distantly related to the African ostriches and Australia's emu (the largest and second largest living ratites, respectively), with rheas placing just behind the emu in height and overall size. Most taxonomic authorities recognize two extant species: the greater or American rhea (Rhea americana), and the lesser or Darwin's rhea (Rhea pennata). The International Union for Conservation of Nature (IUCN) classifies the puna rhea as another species instead of a subspecies of the lesser rhea. The IUCN currently rates the greater and puna rheas as near threatened in their native ranges, while Darwin's rhea is of least concern, having recovered from past threats to its survival. In addition, a feral population of the greater rhea in Germany appears to be growing, though control efforts are underway, and seem to be succeeding in controlling the birds' population growth. Similarly to ostriches and emus, rheas are fairly popular livestock and pets, regularly kept and bred on farms, ranches, private parks and by aviculturists, mainly in North and South America, and Europe.

The name "rhea" was used in 1752 by Paul Möhring and adopted as the English common name. Möhring named the rhea after the Greek Titan Rhea, whose Ancient Greek name (Ῥέα) is thought to come from ἔρα "ground". This was fitting with the rhea being a flightless ground bird. Depending on the South American region, the rhea is known locally as ñandú guazu (Guaraní, meaning big spider, most probably in relation to their habit of opening and lowering alternate wings when they run), ema (Portuguese), suri (Aymara and Quechua), or choique (Mapudungun). Nandu is the common name in many European languages and may sometimes also be heard in English.

†R. anchorenense (Ameghino & Rusconi 1932) [Rhea americana anchorenense Amcghino & Rusconi 1932]
†R. fossilis (Moreno & Mercerat 1891) [Pterocnemia fossilis (Moreno & Mercerat 1891); Rhea pampeana (Moreno & Mercerat 1891)]
†R. mesopotamica (Agnolín & Noriega 2012) [Pterocnemia mesopotamica Agnolín & Noriega 2012]
†R. subpampeana Moreno & Mercerat 1891

Rheas are large, flightless birds with grey brown plumage, long legs and long necks, similar to an ostrich. Large males of R. americana can reach tall at the head, at the back and can weigh up to The lesser rhea is smaller, with a height of Unlike most birds, rheas have only three toes. Their tarsus has 18 to 22 horizontal plates on the front of it. They also store urine separately in an expansion of the cloaca.

A small population of rheas has emerged in Mecklenburg Western Pomerania, northeastern Germany, after several couples escaped from an exotic meat farm near Lübeck in the late 1990s. Contrary to expectations, the large birds adapted well to conditions in the German countryside. A monitoring system has been in place since 2008. By 2014, there was already a population of well over 100 birds in an area of between the river Wakenitz and the A20 motorway, slowly expanding eastward. The population grew steadily for several years. By autumn 2018 their numbers had greatly increased to about 600. As such, local farmers claim increasing damage to their fields, and some biologists say the rheas pose a growing risk to local wildlife. Still protected by German natural conservation law, a local discussion has begun regarding how to handle the situation. Eventually, Mecklenburg Western Pomerania's government allowed limited hunting of the birds, explicitly to just reduce the population's growth and not to wipe them out. At this point, it was generally agreed that the rheas should be allowed to stay in the region. By spring 2021, just 247 rheas were counted; this development was attributed to both the hunting as well as the increased caution of the animals. Several had begun to avoid humans more than previously, and retreated into the woods. Some members of this rhea population have also expanded into other areas; at least twice individual rheas who probably originated in Mecklenburg Western Pomerania were sighted in Brandenburg's High Fläming Nature Park, over from their usual range. There also appears to be a small population of wild rheas in the United Kingdom. In March 2021, a group of about 20 rheas were reported to be running free on a residential estate in Hertfordshire. Local police were unable to identify any owner, so the assumption was that they were wild birds. Once caught, authorities intend to place them in a suitable nature reserve to allow them to develop as a colony.

Rheas tend to be silent birds, with the exception being when they are chicks or when the male is seeking a mate. During breeding season, the male will attempt to attract females by calling. This call is a loud booming noise. While calling like this, they will lift the front of their body, ruffle their plumage, all while keeping their neck stiff. They will then extend and raise their wings, and run short distances, alternating with their wings. He may then single out a female and walk alongside or in front of her with a lowered head and spread wings. If the female notices him, then he will wave his neck back and forth in a figure eight. Finally, a female may offer herself and copulation will commence. although the lesser rhea forms smaller flocks than this. When in danger they flee in a zigzag course, using first one wing then the other, similar to a rudder. During breeding season the flocks break up. The females, meanwhile, may move on and mate with other males. While caring for the young, the males will charge at any perceived threat that approach the chicks including female rheas and humans. The young reach full adult size in about six months but do not breed until they reach two years of age. The lesser rhea is classified as least concern.

Rheas have many uses in South America. Feathers are used for feather dusters, skins are used for cloaks or leather, and their meat is a staple to many people. Gauchos traditionally hunt rheas on horseback, throwing bolas or boleadoras—a throwing device consisting of three balls joined by rope—at their legs, which immobilises the bird. The rhea is pictured on Argentina's 1 centavo coin minted in 1987, and on the Uruguayan 5 peso coin.