Rheas can run at over 60 kilometres an hour. When they need to dodge something, they stretch out one of their long wings like a sail to swerve sharply. Even though their wings can't lift them off the ground, the wings are still useful for steering at full speed - a clever piece of bird engineering.
It is the male rhea who looks after the chicks, not the mother. After several females have laid eggs in the nest he made, the father sits on all of them for 6 weeks until they hatch. When the chicks come out, he raises them, defends them and walks them across the grasslands. A single father rhea may look after 30 chicks at a time.
Rheas eat almost anything - grass, seeds, fruit, insects, lizards and small frogs. Their long legs let them take huge strides, so a small group of rheas can sweep across a grassland feeding as they go. They also swallow small stones to help grind up tough food inside their stomachs.
Long ago, gauchos used to hunt rheas with boleadoras - the rope-and-stone tool we read about. Today rheas in Uruguay are protected, and many farms welcome them onto the pastures. The birds and the cattle live happily side by side.