Rhea americana and Rhea pennata are large, flightless birds native to South America. They inhabit open grasslands and pampas, with Rhea americana found in Brazil and Argentina, and Rhea pennata in Patagonia. They have long legs, a small head, and are known for their speed and agility.

Rhea americana (Greater Rhea) is native to South America, specifically Argentina, Brazil, Paraguay, Uruguay, and Bolivia. Rhea pennata (Lesser Rhea) is found in Argentina, Bolivia, Chile, and Peru.

Rhea americana inhabits open grasslands, savannas, and pampas with a temperate climate. Rhea pennata prefers arid and semi-arid regions, such as Patagonian steppes and puna grasslands, which are characterized by dry conditions and sparse vegetation.

Both species are ground-dwelling birds that are primarily herbivorous, feeding on a variety of plant materials, seeds, and occasionally insects. They play a role in seed dispersal and maintaining the ecological balance of grassland ecosystems. Greater Rheas are more adapted to humid and wetter grasslands, while Lesser Rheas are adapted to drier, harsher environments.