Vertebrate Zoology - V. M. Konstantinov 2011

Chordates
Terrestrial, or Four-Legged, Vertebrates — Vertebrates with Amniotic Membranes
Class Aves — Subclass Neornithes — Superorder Palaeognathae — Order Rheiformes

American ostriches are smaller than African ones, three-toed, brownish-gray in color, about 150 cm tall, and weigh around 30 kg. Their wings are comparatively well-developed. Two species are distributed across the steppe regions of South America (see Fig. 144). The best known is the greater rhea (Rhea americana). They live in flocks of several dozen individuals. Rheas are polygamous. During the breeding season, they break into small groups consisting of one male and 5 to 7 females.

Females lay their eggs in a shared nest. A joint clutch contains anywhere from 15 to 40 eggs, each weighing up to 700 g. Incubation lasts about 42 days. Only the male incubates the eggs and tends to the chicks after hatching. In some areas, rheas are bred in captivity under semi-free-range conditions. They reach sexual maturity at 2 to 3 years of age.



Last update: 13/08/2026

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