Rheidae

The largest New World birds, the rheas are the evolutionary equivalents of Ostriches.

Additional information

The wings, which are used mainly for balance while running and in breeding displays, have a strong and usually concealed claw at the elbow, which is used for defense.

Rheas forage in family groups of between 10 and 30 birds, and are constantly on the move. They often associate with herds of deer, guanacos, and vicunas, a beneficial arrangement in which the birds' keen eyesight and the mammals' ability to pick up scent are combined to detect predators.

In the breeding season, from July to January, males dispute territories by intertwining their necks, biting, kicking, and chasing each other in circles. A successful male attracts mates by herding groups of females into the territory with outstretched wings, while giving a booming call. The male builds the nest, a platform of vegetation concealed in the bushes, and leads the females to it. Each female in the male's harem lays her eggs in turn before leaving to mate with another male and repeat the process. Incubation is carries out by the male only, and lasts for up to six weeks. The chicks are reared by the male only, and young birds remain within the group until they become adult at 2-3 years old.  

Taxonomy

This group of walking birds is only found in South America. There are two species:

• Rhea americana (Greater Rhea)
• Pterocnemia pennata (Darwin's Rhea)

    Rhea americana