Capybara

• 1. Introduction

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  The capybara, Hydrochoerus hydrochaeris, can doze in a river with nothing but its nose above the water. It is also the largest living rodent. A typical adult in the Venezuelan llanos weighs 48.9 kilograms, roughly the size of a large dog. The animal is native to every country in South America except Chile. It lives on savannas and in dense forests, always near a lake, river or marsh. Its numbers are healthy, and in recent years it has become one of the most recognised animals on the internet. How can a creature this big belong to the same order as mice and squirrels? What does it eat, and what hunts it? How do dozens of them live together, and how do they find mates in the water? And why do people in Japan, China and Argentina each see something different in the same placid face? The answers begin with its name and its family tree.

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• 2. Name and Kin

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  Ka'apiûara is the Tupi word behind the name capybara. It is built from kaá, meaning leaf, píi, meaning slender, ú, meaning eat, and a suffix for the one who performs an action. Together they mean one who eats slender leaves, or simply a grass-eater.

  The scientific names say something different. Hydrochoerus joins the Greek words for water and for pig or hog. The species name, hydrochaeris, pairs the Greek word for water with a verb meaning to feel happy or to enjoy. Read literally, the Latin name describes a water pig that delights in water.

  Despite the pig in its name, the capybara's closest relatives are guinea pigs and rock cavies. The agouti, the chinchilla and the nutria are more distant cousins. The capybara shares its genus with only one other living animal, the lesser capybara.

  Since 2002, molecular studies have shown a close bond between Hydrochoerus and Kerodon, the rock cavies. That finding supports placing both genera in a subfamily of the family Caviidae. Older schemes gave capybaras and their extinct relatives a family of their own, called Hydrochoeridae.

  Fossils have caused a quiet housecleaning. Capybara molar teeth change shape a great deal over an individual's life. Material once assigned to four genera and seven species, mostly on the basis of molar shape, was later reread as differently aged members of one species, Cardiatherium paranense. The diversity of fossil hydrochoerines has shrunk substantially as a result.

  In the broad sense that paleontologists use, the fossil genera Cardiatherium, Phugatherium, Hydrochoeropsis and Neochoerus all count as capybaras too.

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• 3. Built for Water

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  An adult capybara measures 106 to 134 centimetres in length and stands 50 to 62 centimetres tall at the withers. Most weigh between 35 and 66 kilograms, and females run slightly heavier than males. The heaviest wild animals on record are a female from Brazil at 91 kilograms and a male from Uruguay at 73.5 kilograms. An 81 kilogram individual was also reported in São Paulo in 2001 or 2002.

  The body is heavy and barrel-shaped, with a short head and a blunt muzzle. Reddish-brown fur covers the upper body and fades to yellowish-brown underneath. Unusually for a rodent, its sweat glands sit on the surface of the hairy parts of the skin. The feet are slightly webbed and the tail is vestigial. The hind legs are a little longer than the forelegs, with three toes behind and four in front. The eyes and ears sit near the top of the head.

  These features suit an animal that spends much of its day wet. Capybaras are superb swimmers and can stay completely submerged for up to five minutes, a skill they use to evade predators.

  Their habitat includes lakes, rivers, swamps, ponds and marshes, as well as flooded savannah and the banks of rivers in tropical rainforest. They have flourished on cattle ranches. In high-density populations, home ranges average about 10 hectares.

  The daily rhythm follows the temperature. As the day heats up, capybaras wallow in water, and they also spend time wallowing in mud. They graze in the late afternoon and early evening, rest around midnight, and graze again before dawn.

  Escaped captives now live in similar wet places around the world. Sightings are fairly common in Florida, though a breeding population has not been confirmed there. In 2011, one capybara was spotted on the Central Coast of California. Late Pleistocene capybaras lived in Florida, and Hydrochoerus hesperotiganites lived in California. Feral capybaras in North America may therefore be filling the niche of those vanished species.

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• 4. A Selective Grazer

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  Surrounded by many kinds of plants, a capybara will often eat the leaves of just one species and ignore its neighbours. It grazes mainly on grasses and aquatic plants, and it also takes fruit and tree bark.

  The seasons reshape the menu. During the wet season it eats grass. In the dry season, when fewer plants are available, it eats a greater variety and switches to the more abundant reeds. Plants eaten in summer lose their nutritional value in winter, so the animals leave them alone then.

  The jaw hinge is not set perpendicular, so a capybara grinds its food back and forth instead of side to side. Its front teeth grow continually to make up for the constant wear from grasses, and the cheek teeth keep growing as well.

  Digestion involves some surprising habits. Capybaras are autocoprophagous, meaning they eat their own feces. This gives them a supply of bacterial gut flora, helps them digest the cellulose in grass, and lets them extract the maximum protein and vitamins from their food. They also regurgitate food and chew it again, much as cattle chew cud.

  Like the guinea pig, the capybara cannot make its own vitamin C. Captive animals that do not receive supplements have developed gum disease, which is a sign of scurvy.

  The maximum lifespan is 8 to 10 years, but wild capybaras rarely live past four. Jaguars, ocelots and cougars hunt them, as do eagles, caimans and green anacondas. Danger can arrive from land, water or sky.

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• 5. The Herd

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  Groups of 10 to 20 capybaras are the usual arrangement, typically with two to four adult males, four to seven adult females, and juveniles making up the rest. Some animals live alone. In the dry season, as many as 50 or 100 may gather around the available water. Males establish social bonds, dominance, or general consensus within the group.

  Capybaras speak in barks, chirps, whistles, huffs and purrs. They can bark like a dog when threatened, and also when females are herding young.

  Scent carries much of the social message. Capybaras have a morrillo, a gland on the snout, and anal glands. Both sexes have both, but males have much larger morrillos and use their anal glands more often.

  The male's anal glands are lined with detachable hairs. These hairs are coated with a crystalline form of scent secretion, which is released when they touch objects such as plants. The mark lasts longer than other scent marks, and other capybaras taste the hairs to read it.

  Animals mark by rubbing the morrillo on objects or by walking over scrub and marking it with the anal glands. They can spread scent farther by urinating. Females usually mark without urinating and mark less often than males. Males also scent-mark females.

  Females mark more often in the wet season, when they are in estrus.

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• 6. Courtship and Young

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  A female in estrus whistles through her nose to announce it to the males nearby. Her scent also shifts subtly, and the males begin to pursue her.

  The female holds the advantage during mating and makes the choice. Capybaras mate only in water. If she does not want a particular male, she either submerges or leaves the water.

  Dominant males guard the females closely, but they cannot stop every subordinate from mating. The larger the group, the harder the watch becomes. Each dominant male secures significantly more matings than each subordinate does. Yet subordinate males as a class account for more matings than each dominant male. Capybara sperm also lives longer than that of other rodents.

  Gestation lasts 130 to 150 days. The average litter has four young, though it can range from one to eight. Birth takes place on land, and the mother rejoins the group within a few hours of delivery. The newborns join as soon as they can move.

  Within a week the young can eat grass, but they keep suckling from any female in the group until weaning at around 16 weeks. They form a smaller group within the main group, and researchers have observed alloparenting, in which adults help raise young that are not their own.

  Breeding peaks between April and May in Venezuela. In Mato Grosso, Brazil, the peak falls between October and November.

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• 7. Living Beside People

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  Hunting has reduced capybara numbers in some areas, yet the species is not considered threatened, and its population is stable across most of its South American range. People hunt it for meat, for pelts and for grease from its thick fatty skin. Some ranchers kill it because they see its grazing as competition for livestock. In other areas it is farmed, which has the side effect of protecting wetland habitats. Rapid breeding helps the species recover.

  In Venezuela, capybara meat is popular during Lent and Holy Week. According to a legend, the Catholic Church once granted a special dispensation that allowed it to be eaten while other meats were forbidden. Many Venezuelans also believe that eating capybara is something only rural people do. Elsewhere in South America, some areas consider the meat unsuitable to eat, while others treat it as an important source of protein.

  Capybaras have adapted well to cities in South America and appear in many zoos and parks. In captivity they may live for 12 years, more than double their wild lifespan. They are docile and usually let people pet and hand-feed them. Physical contact is normally discouraged, though, because their ticks can carry Rocky Mountain spotted fever. Brazilian Lyme-like borreliosis likely involves capybaras as reservoirs, with ticks of the genera Amblyomma and Rhipicephalus as vectors.

  The European Association of Zoos and Aquaria asked Drusillas Park in Alfriston, Sussex, England, to keep the capybara studbook. It records every birth, death and movement, along with how the animals are related, to monitor captive populations in Europe.

  In St. Augustine, Florida, a capybara café invites visitors to give the rodents head scratches.

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• 8. A Symbol of Calm

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  At Izu Shaboten Zoo in Japan, capybaras are given hot spring baths, and video clips of them soaking have drawn millions of views. Other zoos in Japan offer the same treat. The bathing animals inspired plush toys and other merchandise, and they gave rise to the anime character Kapibara-san.

  Capybaras have also gathered fandoms in Japan and China, particularly among young people. This has been linked to the animal's image as a role model for emotional well-being and harmoniousness.

  In the 2020s, the capybara became a figure in meme culture. A common meme format pairs capybaras with the song "After Party" by Don Toliver. A song about capybaras became highly popular on TikTok in 2022. People have described the animals as unflappable and their personalities as "buddha-like", and the capybara has become a symbol of calm.

  In August 2021, Argentine and international media reported that capybaras were disrupting life in Nordelta. This affluent gated community north of Buenos Aires had been built on top of the animals' own wetland habitat. Social media users responded by jokingly adopting the capybara as a symbol of class struggle and communism.

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