Rheas are also known as ñandus or South American ostriches. They are flightless, native to South America, and distantly related to the ostrich and emu. They are grassland birds and prefer open land. Rheas have many uses in South America. Feathers are used for feather dusters, skins are used for cloaks or leather, and their meat is a staple to many people.Rheas have many uses in South America. Feathers are used for feather dusters, skins are used for cloaks or leather, and their meat is a staple to many people.