Greater rhea

Class: Aves
Order: Struthioniformes
Family: Rheidae
Genus and Species: Rhea americana
  • Large gray bird with long, curved neck and long legs
  • close-up of head of rhea. It has a long neck and long eyelashes.
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Greater rhea

The largest South American bird, rheas are flightless and resemble ostriches.

Physical Description

Although rheas look similar to ostriches, they are much smaller and have three toes on each foot, while ostriches have two toes on each foot. Their heads, necks and thighs are all covered with feathers. Rheas cannot fly. However, they have unusually long wings for flightless birds. They use their wings like an airplane rudder to help them dodge predators and for balance while running.


Rheas are the largest South American bird. Rheas weigh between 33 and 66 pounds (15 to 30 kilograms) and stand 3 to 5 feet tall (0.9 to 1.5 m) with the males larger than the females. They have long necks and legs. Their plumage is mostly gray and brown with white underparts. There are no tail feathers but the wings are large and are used for maneuvering while running.

Native Habitat

The greater rhea lives in southeastern South America, including Brazil, Bolivia, Uruguay, Paraguay and Argentina. Rheas live in grassland and semiarid scrubland. During the breeding season, they stay near rivers, lakes or marshes. They occur on upland and lowland plains in most parts of South America.

Food/Eating Habits

Rheas are omnivorous, preferring broad-leafed plants and clover. However, they eat a variety of seeds, roots, fruits, insects and small vertebrates, such as lizards, frogs, small birds and snakes. Rheas continuously move as they feed.

At the Smithsonian's National Zoo, rheas eat ratite pellets and greens.

Social Structure

Rheas generally live in groups, although breeding males are solitary for part of the year.

Reproduction and Development

Their breeding season is from August to January, depending on the region. Males have a dark collar at the base of its neck during the breeding season. Males will call females with a booming call and court two to twelve females with an impressive wing display. Once mating has occurred, the males build nests, which are shallow depressions in the ground. Each of the females lay up to five gold- colored eggs in the male's nest over a period of seven to ten days (up to 60 eggs total). After the eggs are laid, the male incubates the eggs for about six weeks. The male cares for the chicks alone. When male rheas are taking care of their young, they will charge at any creature that comes too close to them, including female rheas and humans.

The rhea population has suffered through hunting and habitat loss, although it is still relatively abundant. In 1980, over 50,000 skins were traded; however a permit is now needed for their export and import. Rheas are considered pests near agricultural areas because they will eat almost any crop.