Capybara: Hydrochaeridae

Capybaras are social, living in groups of six to twenty animals, although groups of one hundred or more have been reported. The group has a dominant male, several adult females, their offspring, and several submissive adult males. The group is usually composed of family members and outsiders are rarely accepted. There is a social hierarchy in the group as a whole and within female members. The dominant male aggressively and sometimes viciously enforces this hierarchy.

In the wild, capybaras are usually active in the early morning and twilight. During the heat of the day, they rest intermittently in shallow beds in the ground or shaded areas of shallow water. In areas where there are higher concentrations of people, the capybara has become nocturnal, meaning it is most active at night.

When a capybara becomes startled or alarmed on land, it will run with a gallop much like that of a horse. If it feels it is in immediate danger, it will seek safety in water where it can stay submerged for about five minutes. With its partially webbed feet, the capybara is an extremely capable swimmer and diver. It can swim while submerged or with its eyes, nostrils, and ears just above the water's surface, much like a hippopotamus. It can also hide among water plants, with just its nostrils above the water line. Capybaras can make several vocal sounds, including a low-pitched clicking noise when it is content; long, sharp whistles; short grunts; and a purr to indicate submissiveness. When a capybara spots a predator or feels it is in imminent danger, it will bark. Nearby capybaras will stand motionless at alert. If the caller continues to bark, they will race into the nearest water and gather closely in a group, with their young in the center for protection.

Capybaras are somewhat territorial and the home territory of a herd or group averages about 200 acres (80 hectares). The Newborns capybaras can see soon after birth and eat grass after one week. Young capybaras stay together in a group and females will allow infants other than their own to nurse. (Erwin and Peggy Bauer/Bruce Coleman Inc. Reproduced by permission.) size of the range varies, depending on the season. Home ranges of groups often overlap. A group tends to get larger during the dry season and smaller in the wet season when groups tend to break into smaller groups as more marshes and wetlands are available. There are core areas within a group's range that it will protect for its exclusive use.

Mating occurs throughout the year but is highest in April and May. Females usually have one litter per year although two litters are not uncommon if conditions are favorable. The female gestation period, the time they carry their young in the womb, is 104 to 156 days. Litter size ranges from one to eight, with five being the average. Newborns can see soon after birth and can eat grass after one week. Young capybaras stay together in a group and females will allow infants other than their own to nurse. Both males and females reach puberty, the age of sexual maturity, at about fifteen months of age. The average lifespan in the wild is eight to ten years. In captivity, several capybaras have lived for more than twelve years.

Capybaras have several natural predators, animals that hunt them for food, in the wild, including jaguars, anacondas (large water snakes), and caiman (KAY-mun), a large reptile similar to alligators and crocodiles. Young capybaras are eaten by foxes, vultures, and wild dogs.