Capybaras eat plants, mostly grass. Their babies are usually born in litters of four at one time. They can start to eat grass once they are about a week old, but they will also keep nursing from their mothers and even from other grown females until they are about four months old. They live in large groups, usually 10-30 capybaras together. Some groups have even had 100 capybaras. They talk to each other using many sounds: clicks, grunts, whistles, and barks. 