Mating occurs year-round, and takes place in the water. A pregnant female leaves the group to give birth in a sheltered spot nearby. She rejoins the group the same day, leaving her newborns in a nest. The young join the herd in three to four days and eat grass within their first week. Until weaning, young stay in a close-knit group kept together by nursing mothers. When multiple litters are present, mothers suckle all young and not just their own offspring. The gestation period is 150 days, and 2 to 7 young are born.

The young have a continuous purring cry, which probably keeps them in communication with mothers. They are vulnerable to vultures, wild dogs, caimans, and foxes.

Predators include jaguars, foxes, birds of prey and wild dogs. If a predator is spotted, a capybara will bark to make other members of the group aware. They evade predators by going into the water.

There is a scent gland located on the nose, and one on the anus. The male scent gland on the rear is odiferous. Both glands are used to mark territory.

European naturalists once called the capybara the “water pig” and the “Orinoco hog.”

The capybara is descended from an animal that lived in North and South America. It was almost twice as long and nearly eight times as heavy as the capybara.

The scent gland on the top of the adult male’s nose is called morillo, which means “small hill” in Spanish.