Mammals: Capybara

Range: Central America and South America Habitat: swampy, grassy regions bordering rivers, ponds, streams, and lakes

A rodent of unusual size

Is it a beaver without a tail? A hairy pig without a snout? No! It’s a capybara, the largest rodent in the world. Standing about two feet tall and built somewhat like a barrel with legs, the capybara is found on Central and South American riverbanks, beside ponds, and in marshes or wherever standing water is available. Africa has hippos, the Americas have capybaras! The capy has long, light brown, shaggy hair, a face that looks like a beaver’s, no tail, and slightly webbed feet. Originally thought to be a pig of some sort, we now know that the capybara is a rodent, closely related to cavies and guinea pigs.

Water pig

The capybara’s scientific name, Hydrochoerus, means “water hog,” and the capy is always found near water, typically in groups of 10 to 30 animals. Water is a source of life for the capybara, as the animal eats water plants and grasses and uses the water itself to escape from danger. In fact, a capybara can stay underwater for up to five minutes at a time to hide from predators. It uses those webbed feet (four toes on each front foot and three on each back one) to swim as well as walk. The capybara has something in common with the hippo: its eyes, ears, and nostrils are all found near the top of the animal’s head. A capy can lift just those parts out of the water to learn everything it needs to know about its surroundings, while the rest of its body remains hidden underwater.

Capybaras also wallow in shallow water and mud to keep cool during a hot day before wandering out in the evening to graze. They tend to eat around dawn and dusk, but if capybaras feel threatened, they wait until the safe cover of night to eat.

Won’t you join me for lunch?

Because capybaras really are rodents, they share some common features with the mouse, squirrel, and porcupine. The most well-known are probably those ever-growing front teeth. Capybaras use their long, sharp teeth for grazing on grass and water plants; an adult capybara can eat 6 to 8 pounds (2.7 to 3.6 kilograms) of grass per day! During the dry season, when fresh grasses and water plants dry up, capybaras eat reeds, grains, melons, and squashes They also eat their own poop in order to get the beneficial bacteria to help their stomach break down the thick fiber in their meals. At the San Diego Zoo, the capys are offered alfalfa grass and leaf eater biscuits, with apples, carrots, and yams offered as special treats.

Even though rodents aren’t closely related to ruminants like goats, cows, and giraffes, capybaras will regurgitate their food in order to chew it some more. They can chew their food from side to side, like a camel, rather than up and down, like we do. This is a good way to eat tough plant materials.

All in good company

Capybaras usually live in groups of up to 30 animals, though during the dry season, groups of more than 100 can be found sharing a territory. Usually, a group stays in its home range of about 50 acres (29 hectares), although home ranges of different groups can overlap. This makes it easy for youngsters to find new groups to join once they have reached maturity and are pushed out of their original family group.

A dominant adult male is in charge of several adult females, their babies, and a handful of juveniles. He keeps everyone in line by growling and chasing the others, but serious fights with injuries are rare.

Lots of helpers

In warmer climates, breeding may occur all year long, although the wet season is the most popular time. Capybara courtship seems to be a water sport, and breeding occurs in the water. Five to six months later, the pregnant female leaves the group to give birth in a quiet spot. A female usually has one litter of young each year, but if the conditions are good and food is plentiful, she might produce a second litter later in the year. The newborns are up and about after three or four days and are ready to join the group. They start to graze when only a few days old and nurse for about 16 weeks. All of the females in the group help to care for and even nurse each other’s babies. It is helpful to have many sets of eyes watching out for the youngsters, since they can easily fall victim to caimans, ocelots, harpy eagles, and anacondas. Adult capybaras have one main natural predator—the jaguar—but humans hunt them as well.

Chatty capys

Capybaras are incredibly vocal animals and communicate using barks, chirps, whistles, huffs, and purrs. They spend much of the day chattering back and forth to keep track of one another. Much like prairie dogs, the capybara's first line of defense is a warning bark. If one animal feels threatened, the whole group will bark until danger has passed. This alarm call can also be used to scare potential predators away.

A capybara female and her young use vocalizations to keep in close contact, even if another female is caring for the baby. Youngsters purr and whistle for adults if they get separated from the group, and a quiet chirping is used between adult females and youngsters when the group is moving.

Do you smell that?

Sound isn't the only way capybaras communicate: they also use scent. Capybaras have a pair of scent glands on their rump that they use to mark territories and communicate with one another. Males often walk right over bushes in order to mark them and can leave behind hairs that are crusted with the oily, smelly stuff. The males also mark females! Females scent mark less often than males do, mostly during the wet season when they are looking for a mate.

Capys also have a scent gland on the top of their nose called a morrillo (Spanish for “small hill”), though the males’ is much larger. The bigger the morrillo, the more dominant the male. Dominance is important for group living, but capybaras are usually peaceful toward one another. The most dominant male is usually found in the center of the group, with access to the best food and the females. The females surround him with the youngsters, and the subordinate males are found on the outskirts.

Capybaras at risk?

The capybara is not currently classified as an endangered species. It was in trouble not too long ago, though, due to hunting. Local people have used these animals as a food source for centuries and have even been seen wearing capybara teeth as ornaments. Now, capybaras are being farmed for their meat as part of a mammal management plan in Venezuela and Colombia. This helps to protect the capybaras left in the wild and their wild habitat, which, in turn, helps all of the plants and animals that call that habitat home.