Rhea (bird) to be growing. The genus name was given in 1752 by Paul Möhring and adopted as the English common name. Möhring named the rhea based on the Greek Titan Rhea, whose name is derived from the Greek "Rhea" () from έρα "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
Flightless bird more species of flightless birds (including the kiwi, several species of penguins, the takahe, the weka, the moa, and several other extinct species) than any other such location. One reason is that until the arrival of humans roughly a thousand years ago, there were no large land predators in New Zealand; the main predators of flightless birds were larger birds. Ratites belong to the superorder Palaeognathae birds, which include the volant tinamou, and are believed to have evolved flightlessness independently multiple times within their own group. Some birds evolved flightlessness in response to the absence of predators, for example on