The Rhea is a large ratite native to South America and it’s related to the Ostrich and the Emu. There are two extant species: the Greater Rhea and the Lesser Rhea, both are currently rated as near-threatened in their native ranges. The two subspecies don’t vary a lot in weight, but the main differences are the height and the body shape. The Greater Rhea is taller and looks bigger, while the Lesser Rhea is shorter and has a more compact body. In general, rheas are large, flightless birds with grey-brown plumage, long legs and long necks, similar to the Ostrich. They have 3 toes in each foot, and relatively spread large wings that act like sails while running.
The male rhea is slightly larger than the female and can reach a weight of 40 kg. Rheas are polygamous, with males courting between two and twelve females. After mating, the male builds a nest, in which each female lays her eggs in turn. The females lay up to 50 greenish yellow eggs then the male incubates them for almost 6 weeks. The male will use a decoy system and place some eggs outside the nest and sacrifice these to predators, so that they won’t attempt to get inside the nest. Eggs that survive predators get rotten and attract flies and that provides a food source for the father and the chicks when they hatch. The male may use another subordinate male to incubate his eggs, while he finds another harem to start a second nest.
The chicks are herded by the male only, while the female seeks another mate to lay another clutch of eggs. The young reach full adult size in about six months but do not breed until they reach two years of age. During the non-breeding season, rheas frequently associate with Deers or Guanacos, forming mixed herds like those of Ostriches, Zebras, and Antelopes.
Rheas prefer broad-leafed plants but they also eat fruits, seeds and roots, as well as insects such as Grasshoppers and small reptiles and rodents. They resemble a source of food especially for native people as they provide feathers which are used for feather dusters making, skins for cloaks or leather, eggs and meat which is a staple to many people. The natural predators of rheas include the Cougar and the Jaguar which attack rheas of any age, Feral Dogs that threaten the hatchlings and Armadillos that feed on the eggs.