Rhea

Rheas, also known as ñandus 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. Etymology 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 is thought to come from "ground". This was fitting with the rhea being a flightless ground bird. Depending on the South American region, the rhea is known locally as (Guaraní, meaning big spider, most probably in relation to their habit of opening and lowering alternate wings when they run), (Portuguese), (Aymara and Quechua), or (Mapudungun). is the common name in many European languages and may sometimes also be heard in English. Taxonomy and systematics