Greater rheas, rhea Americana, are the largest birds in South America. They stand 3 to 5 feet (0.9 to 1.5 meters) tall, and weigh 50 to 55 pounds (20 to 25 kilograms) with males being slightly larger than females. Like ostriches, cassowaries and the like, greater rheas are flightless birds. Their wings do however, allow them to balance themselves as well as change direction whenever they run. Greater rheas can reach speeds of over 37 miles (60 kilometers) per hour.
Greater rheas can be found only in South America, specifically Argentina, Bolivia, Uruguay, Paraguay and Brazil. They tend to inhabit open woodlands, tall grasslands, and wooded savannahs. During the winter, great rheas become social and will flock together in groups that can contain more than 30 individuals. They will even join with other large animals such as deer and guanacos to form mixed herds.
The diet of greater rheas mainly consists of plant matter including leaves, seeds, fruits and roots. They will however, eat insects, lizards, frogs, small birds and even snakes. They have even been known to eat flies that gather around the bodies of dead animals. Greater rheas will swallow pebbles in order to help them grind down food in their gizzard.
Mating season for greater rheas takes place in the spring. During this time, females will break off into small groups while males will become solitary and fiercely territorial. They will intertwine their necks, bite and kick any other males that wander into their territory. When greater rhea males find females, they will attempt to court them with a display that involves calling, running around the females with their wings spread, and even standing next to them with their necks lowered and their wings shaking. Males will also prepare the nests, which are just depressions in the ground. All the females in a group will lay eggs in the nest, with up to 50 eggs in there at a time. The males will incubate and raise the chicks while the females will leave to mate with others and lay more eggs. After about 35 to 40 days, the eggs will hatch. The father will protect the young and feed them for about 4 to 6 months, sheltering them if they get too hot, too cold, or if they feel threatened. A male may even take in chicks that have become separated from their parents and ‘adopt’ them. Even after their parents stop taking care of them, the chicks will remain in a group for a long time. If the chicks can survive, they can live to be 15 years old.
Greater rheas face threats from many fronts. Loss of habitat, over hunting, and even inbreeding are leading to a decline in their numbers. Hopefully, a solution can be found that allows greater rhea numbers to increase throughout their ranges. After all, such a unique bird species deserves to live and prosper for many years.
