How to Identify the Sex of a Rhea

A Lesser Rhea or Darwin's Rhea is a large flightless bird that lives in South America, and is referred to as the "South American Ostrich." The birds stand 35 inches tall, have dense, golden-brown feathers that cover its body and head. Rheas are prized for their hide and meat, which is similar to beef, only sweeter. It got its name from Rhea, who is the wife of Cronus, the Titan king of time and the ages in Greek mythology. Read on to learn how to identify the sex of a rhea.

Difficulty: Moderate

Instructions

1. Observe rheas as they socialize. Male rheas are more vocal. The females are almost silent.

2. Measure rheas. The males of the species are taller than the females.

3. Watch rheas during breeding season. Male rheas will become aggressive with other males as they try to attract females.

4. See which bird builds a nest. Male rheas are the ones that create a shallow nest in which the rhea eggs are hatched.

5. Observe how the eggs are cared for by the rhea. The females lay the eggs by the nest. It is the male rhea that incubates the eggs and raises the chicks. He can care for up to 30 chicks at a time, as more than one female lays her eggs by the male's nest.

6. Watch how the rheas interact after the chicks are born. The male rhea is more aggressive as he protects the chicks from danger, and even other rheas, both male and female. Male rheas have been known to attack riders on horseback.

7. Take blood from a rhea and test it. The presence of estrogen and testosterone can be indications of the sex.

Resources

• Fresno Chaffee Zoo for Information About Rheas