RHEA, the generic and usual book-name of the South American ostriches or nandus, which, although true ratite birds and occupying the place of Ostriches in the American avifauna, yet differ so greatly from the African species that ornithologists universally rank them as a distinct family (Rheide) or even order (Rhea). Conforming to the general type of the ostriches, the rheas differ in having three toes with large claws, the head and neck fully feathered, the flowing plumes absent from the wings and especially the tail, the ischiatic in stead of the pubic bones forming the pelvic symphysis and the palatal structure peculiar in several respects. Three species of Rhea have been described; R. americana, found throughout the greater part of South America; R. mae rorhyncha, which is confined to northeast Brazil and is distinguished by its darker color and longer bill; and R. darzeini, of southern Argen tina, which is smaller and has tarsi covered with small scales instead of scutes as have the others. The newly-hatched young of the latter are said to have the legs feathered to the toes.
Rheas are known to the natives as nandus or emas (the latter a corruption of emu intro duced by the Portuguese) and live in small parties on the pampas and dry plains, where they associate with wild horses, deer and guanacos. In general habits they closely re
semble the ostriches (q.v.), but usually run with the wings lowered instead of elevated. They are said to be able to swim across wide rivers. Because of the well-developed syrinx, which is absent in the ostriches, the male rheas have a loud, resonant call, especially heard dur ing the mating season, when they also fight viciously. They are polygamous and the male incubates the score or more of eggs deposited by several females in one nest. They are omniv orous. Although lacking the precious plumes of the ostrich the feathers of the rhea have a commercial value in the manufacture of feather dusters. Many thousands are killed by shoot ing or with the bolos, or are run down with hounds or horses and clubbed to death. In many places they are threatened with extinction; but, although they breed readily in confinement, no efforts to raise rheas on a commercial scale appear to have been made. Consult Darwin, 'Voyage of the Beagle' (New York 1889) •, Mosenthal and Harting, (Ostriches and Ostrich Farming' (London 1877).