Capybara

Quick Take

• The capybara's giant size isn't just genetics. It traces back to a bizarre quirk in one specific hormone that does something no other rodent's does. Discover the insulin quirk →
• Capybaras can vanish from a predator's sight in seconds, thanks to an anatomy that is specifically engineered for one clever disappearing trick. See the aquatic anatomy →
• Their diet looks simple, but capybaras have a digestive habit so strange it puts most animals to shame. Explore the strange digestion →
• Capybara newborns are unlike almost any other mammal's young, hitting the ground running in a way that seems almost impossible. Meet the remarkable pups →

The Capybara is a large, semi-aquatic rodent that inhabits the waterlogged regions of Central and South America. Closely related to other South American rodents such as chinchillas and guinea pigs, the Capybara is the largest rodent in the world, weighing up to 174 lbs (79 kg) and measuring up to about 4.4 feet (1.3 meters) long.

Despite their enormous size, though, Capybaras have adapted well to life in the water and have a number of distinctive characteristics that aid their amphibious lifestyle, including the webbed skin between their toes, which is particularly helpful when swimming in water.

Interestingly, the common name of the Capybara is thought to mean “Master of the Grasses”, whilst its scientific name comes from the Greek word for water hog.

Species and Evolution

Capybaras (genus Hydrochoerus) are two species of large semi-aquatic rodents that inhabit freshwater environments in Central and South America. The larger of the two species, and the subject of this article, Hydrochoerus hydrochaeris, can grow up to 4.3 feet long and weigh up to 174 pounds. The lesser capybara, H. isthmius, is smaller, reaching lengths of 3 feet and weighing 62 pounds.

Both species of capybara have ancestors who evolved in Africa and arrived in South America around 40 million years ago during the mid-Eocene. Its relatives are all regular-sized rodents, such as rock cavies and guinea pigs, but capybaras, like elephants, have developed a form of gigantism. Capybaras have a unique form of insulin that, in addition to regulating blood sugar, also tells cells to divide. Millions of years of natural selection increased their insulin’s ability to tell their cells to divide, boosting their growth to its present stature. They are, literally, giant rodents.

Anatomy and Appearance

The Capybara is a heavy, stocky-looking animal with a short head and muzzle in comparison to its body and a stubby tail. Their heads are square instead of pointed — just one of many characteristics that make them stand out among their rodent cousins.

One of the Capybara’s most distinctive features is the fact that its eyes, ears, and nostrils are all positioned on top of its head, meaning that they still have excellent sight, sound, and smell whilst in the water. The placement of these features also means that when threatened, the Capybara can retreat into the water, only leaving these parts of its body exposed to hide from potential predators.

Capybaras have reddish-brown fur on most of their bodies and a lighter color on their underbellies. Another unusual trait that the capybara has is sweat glands found on the surface of the hairy parts of its skin — making them the only rodents who sweat. Webbed feet and vestigial tails also make the capybara uniquely adapted to their watery environment. Their hind legs are longer than their forelegs, and they have only three toes on their rear feet and four toes on their front, making it easier to climb from the water onto the muddy banks. All of those characteristics plus their giant size certainly make the capybara stand out among all rodents.

Size and Weight

Adult capybaras can grow up to 4.4 feet in length and stand about 2 feet tall. They can sometimes weigh as much as an average adult woman. Additionally, female capybaras weigh slightly more than males. They can grow up to 4.3 feet long and weigh up to 154 pounds. The lesser capybara is smaller, reaching lengths of 3 feet and weighing up to 62 pounds.

Distribution and Habitat

The Capybara is found throughout a variety of habitats in Central and South America, provided that there is a constant source of standing freshwater. They are found in Panama, Colombia, Venezuela, and Peru, down through Brazil and Paraguay, and into northern Argentina and Uruguay, where they are most commonly found in swamps, marshes, rivers, and lakes.

The Capybara can be found inhabiting grassy plains and even in rainforests, where they occupy territories in herds, with these areas reported to be adequate territories year-round even with the differing seasons. During the dry season, the Capybara must have water and areas where they are able to feed (often small sandbars in the water), but in the wet season, when the area floods, they must still be able to graze, which they often do on the grassy banks.

Behavior and Lifestyle

The Capybara is a very sociable animal that tends to inhabit densely vegetated areas close to the water in herds of around 20 individuals, which are usually made up of a dominant male with a number of females and their young. Capybara herds occupy very stable home ranges that are known to vary in size depending on the size of the herd to ensure that there is enough food, and although small parts of their territory may overlap those of another herd, they will tend to chase intruders off their patch.

The Capybara prefers naps to typical nocturnal slumber, choosing instead to doze throughout the day on the riverbanks or to nod off while wallowing in the mud. They begin to emerge onto land in the early evening when they graze on grasses and aquatic plants, which the Capybara will continue to do throughout most of the night.

Reproduction and Life Cycles

In a Capybara herd, it is only the dominant male that has the breeding rights to the females, and although it can occur all year round depending on the conditions, the breeding season tends to be during the rains in April and May. After a gestation period that lasts for around five months, the female Capybara gives birth to between 1 and 8 pups on land. Capybara young are very well developed at birth and not only have all their fur and can see, but are also able to run, swim, and dive within hours of birth.

The female rejoins the main group within hours with her newborn offspring, which begin to eat grass after about a week (although they will continue to suckle milk from their mother until they are around four months old). The Capybara tends to live for up to 10 years in the wild and slightly longer when kept in captivity.

Diet and Prey

The Capybara is a herbivorous animal that only eats plant matter in order to acquire all of the nutrients it needs. The diet of the Capybara is mainly made up of grasses and aquatic plants, along with fruits and berries and occasional soft tree bark. Despite spending a number of hours during the night grazing, the Capybara is quite fussy, with around 75% of their diet involving between three and six different species of plants.

Like all other species of rodent, their two front teeth grow continuously throughout their lives, meaning that they must gnaw and chew their food to grind it down, which they do in a back-and-forth motion rather than a side-to-side one. They are also known to both regurgitate their food in order to chew it again (much like a cow) and also eat their own droppings, which help to break down the cellulose in the grass and aid their digestive system generally.

Predators and Threats

despite their large size and secretive aquatic nature, their slow and gentle disposition makes them a rewarding meal for numerous hungry predators throughout their natural range. Wildcats, including jaguars, pumas, and ocelots, are the primary predators of the capybara, along with caimans and eagles that can hunt the younger ones from the sky above. The Capybara is also one of the best sources of food for the world’s heaviest snake, the anaconda, along with other species of large snakes.

The Capybara is also hunted by humans in parts of its natural range for both its meat and the hide, which is prized by some. Although the global Capybara population is not considered to be under threat, numbers in these areas have declined. Habitat loss also affects Capybara populations throughout Central and South America as they are specifically adapted to life in their unique watery wilderness.

Interesting Facts and Features

Capybaras never stray far from water; when one senses danger, it gives a short bark that encourages the herd to quickly scuttle into the water to hide. They are so well adapted to going unseen in the water that the Capybara is actually able to hold its breath for up to five minutes after diving in. Although Capybara herds tend to average between 10 and 30 individuals, larger groups are not uncommon, with some numbering up to 100 members in home ranges generally larger than those of smaller groups.

Capybaras are known to communicate with one another using both scent (which is secreted by their glands) and sound and have a number of different vocalizations including whistles, barks, grunts, and squeals.

Relationship with Humans

Due to their slow and generally gentle nature, humans have lived alongside capybaras peacefully for hundreds of years. Although they are not aggressive animals, they are often killed in certain areas for their meat and skin, which has led to population declines in these regions.

The Capybara has also been affected by human activity in their native regions in general, including both growing human settlements and land clearance for agriculture. It is in these areas, particularly when there is not an adequate supply of food available, that some capybaras have been known to enter crop fields where they can cause a great deal of damage and can be seen as pests.

Conservation Status and Life Today

Today, the Capybara population throughout Central and South America remains fairly stable and because they are still common in much of their natural range, the Capybara is listed as Least Concern from becoming extinct in their natural environments in the near future by the IUCN Red List. Population numbers in certain areas, however, have declined due to hunting, and others are affected by the loss of their natural habitat from deforestation and increasing pollution levels in the water.