South America's ostrich cousins that never left the ground
Rheas—also called ñandú—are South American ratites, flightless birds without a keeled sternum, distant kin to ostriches and emus. Most authorities accept two living species: greater (American) and lesser (Darwin's) rhea. Paul Möhring used the name rhea in 1752.
Paul Mohring coined the name in 1752 after the Greek Titan Rhea, whose name may come from a word for ground, apt for a bird that cannot fly. Mathurin Jacques Brisson set up the genus in 1760 with the greater rhea as type. The lesser rhea once had its own genus, Pterocnemia, until the South American Classification Committee, the last holdout, agreed to fold it into Rhea on 7 August 2008. A supposed fourth species, Rhea nana, rested on one Patagonian egg described by Lydekker in 1894. Among ratites, rheas rank just behind the ostriches and the emu in size.
They look like small grey-brown ostriches, all legs and neck. Big greater rhea males stand about 170 centimetres tall and weigh up to 40 kilograms, while the lesser rhea reaches about 100 centimetres. Found wild only in seven South American countries, from Peru and Brazil south to Chile, Argentina and Uruguay, they favour open ground; greater rheas keep to lowland grassland, pampas and chaco woodland, seldom above 1,500 metres, and breed near water. Mostly they eat broad-leafed plants, plus fruit, seeds, insects, small reptiles and rodents, often grazing alongside cattle and deer.
Outside the breeding season they gather in flocks of 20 to 25 and escape danger by zigzagging, using their wings as rudders. Breeding males boom loudly with body raised and feathers ruffled. Both sexes take several partners: a male courts two to twelve females, scrapes a grass-lined nest where they all lay, and alone incubates ten to sixty eggs.
Escaped birds from a meat farm near Lubeck in the late 1990s founded a wild population in northeastern Germany that reached about 600 by autumn 2018, angering farmers, and about 20 roamed a Hertfordshire estate in 2021. At home, the greater and puna rheas are near threatened as habitat shrinks, though the lesser rhea is of least concern. Gauchos hunt them with bolas, and the birds appear on Argentine and Uruguayan coins.
Source: Rhea (bird)
