ORDER

Struthioniformes (kiwis, ostriches, emus, rheas and cassowaries)

FAMILY

Rheidae (Rheas)

HABITAT AND RANGE

Lesser rheas (Darwin’s rheas) are found only in the Andes of South America (Chile, Peru, Argentina and Bolivia). They live in the high plains in semi desert areas at elevations of 9,000 to 12,000 feet.

IDENTIFICATION

Lesser rheas generally stand about 1 meter tall and can weigh up to 55 kg. They have long legs and three large toes which allow them to be very agile on land (they are flightless). There is a strong claw at the end of the wing that can be effectively used as a weapon. Adult plumage is generally brown with white freckling while juveniles lack the freckling.

DIET

Lesser rheas are omnivorous eating grasses, herbs, plants, fruits and to a smaller degree insects and small mammals. It consumes little water as its hydration needs are often satisfied by the plants it eats.

REPRODUCTION AND LIFESPAN

At the onset of the season, males compete for territory in short fights. After securing territory, males attempt to attract females into it by running at them quickly with outspread wings. When he has succeeded in gathering 2-12 females, he then begins a courtship display, which involves various calls and running around them, shaking his wings. After copulation, the male leads the females in a group to the nest, where they lay their eggs one after another. Then the females leave, also in a group. In the weeks that follow, they return every 2 or 3 days to deposit more eggs. The male is then left on his own for incubation and chick-rearing. Incubation begins 2-8 days after egg laying begins, and may continue for 35-40 days. The nest usually ends up with 13-30 eggs. When one chick hatches, it begins calling, stimulating the others to hatch. Thus they all hatch synchronously in a period of 24-28 hours. The chicks are grayish brown with blackish stripes. The period of parental care is 6 months, but the juveniles generally remain in their groups until they are sexually mature at 2-3 years old. Rheas can live up to 20 years in the wild and up to 40 years in captivity.

NOTES

Rheas are threatened or endangered in some areas due to habitat loss and hunting for their feathers, meat and eggs. Rheas have excellent vision and acute hearing. They are also fast runners, able to reach speeds of up to 60 km/h. Surprisingly they are also strong swimmers.