Capybara  (Hydrochoerus hydrochaeris)

Classified as Least Concern (LC) on the IUCN Red List (1).

At over a metre in length and weighing as much as an adult human, the capybara is the largest rodent in the world. A stocky, somewhat pig-like animal, it is characterised by a large, blunt head, heavy muzzle, short, robust legs and rudimentary tail (2) (3) (4). The hair is coarse and sparse, and varies in colour between dark brown, reddish and yellowish brown (2) (3) (5), occasionally with some black on the face, the outer surface of the limbs, and on the rump (4) (6). The capybara shows a number of adaptations to a partly aquatic lifestyle. It is able to swim with only the nostrils, eyes and short, rounded ears protruding out of the water, as they are placed high on the head (3) (4) (7), and the body contains a large amount of fatty tissue, giving it a neutral buoyancy in water (6). The feet are also partially webbed. Each of the forefeet has four toes, while the hindfeet have only three, and each toe bears a strong, hoof-like claw (2) (4) (5). The capybara often sits on its haunches like a dog, but, unlike many other rodents, is unable to hold food in its forefeet (2).

The male capybara can be distinguished from the female by the obvious, highly developed scent gland on top of the snout. Known as a morillo, this dark, naked, raised area secrete a copious white, sticky fluid, thought to be involved in signalling dominance status (3) (4). In addition to using scent, the capybara also communicates through a variety of vocalisations, including growls, whinnies, alarm barks, whistles, and a constant guttural purr emitted by the infant (2) (3) (4). This species is distinguished from the lesser capybara, Hydrochoerus isthmius, by its larger size (5), although there is some confusion over the distributional boundaries of these species (1).

The capybara occurs over much of South America, to the east of the Andes, from Colombia and Venezuela south to northern Argentina (1) (3) (4).

The capybara inhabits a variety of lowland habitats close to water, ranging from rivers and lakes in rainforest, to marshes, brackish wetlands, swamps, and seasonally flooded grassland and savanna (2) (3) (4) (5). Suitable capybara habitat needs a mixture of water, dry ground and pasture (5), and habitat use may change seasonally to follow the availability of these resources (8). The capybara is most numerous on the seasonally flooded grasslands of the Llanos in Venezuela and Colombia, and the Pantanal of Brazil (2) (5), giving it its common name, which translates as “master of the grasses” (6) (7).

The capybara is an efficient grazer, able to crop the short, dry grasses left at the end of the tropical dry season (3). Although the diet comprises mainly grass, it also includes aquatic vegetation, such a water hyacinths, as well as other plants, grain, and sometimes fruits (2) (3) (4). When alarmed, the capybara is capable of running swiftly over land, and often dives into water to escape (2) (4) (6). A strong swimmer, it is able to stay underwater for up to five minutes at a time (3) (6). The species is normally active morning and evening, resting during the heat of the day, but has apparently become nocturnal in areas where it is persecuted by humans (2) (4).

A social species, the capybara is typically found in family groups of around 10 to 30 individuals, comprising a dominant male, one or more females (which are often related), young of various ages, and one or more subordinate males. Most solitary individuals are male. Group size may depend on habitat, and in the dry season several groups may gather around dwindling pools, forming temporary aggregations of up to 100 or more animals. However, when the wet season returns, these aggregations split into the original groups that formed them (3) (5) (8). All adults in a group help defend the territory against intruders, and regularly scent mark the area using secretions from anal scent glands. These secretions may also be used for individual recognition, as the proportions of chemicals they contain differ between individual capybaras (3) (8).

Capybaras mate in the water (3) (6). The female usually gives birth to a single litter each year (4) (6), at the end of the rainy season, after a gestation period of around 150 days (3) (8). Usually, up to eight young are born, and are highly developed at birth, able to follow the female and even eat grass within the first week of life (3) (4) (5). Weaning takes place at around 16 weeks (4), although milk is a relatively minor part of the infant’s diet compared to grass (5). All young within the group tend to stay together in a crèche, and may suckle from any nursing female (3) (8). The capybara reaches sexual maturity at around 12 to 18 months, and may live for up to 10 years in the wild, or to 12 years in captivity (3) (4).

The capybara is extensively hunted for its meat and hide, as well as for a grease from its thick, fatty skin, which is used in the pharmaceutical trade (4) (5) (9). The hide is used to make high-quality leather (5) (6), for which there is a large internal market within South America (1), and the fur may be used to make gloves (10). The capybara is also sometimes killed by farmers as a pest, either because it may attack cereal or fruit crops, or because it is mistakenly viewed as a competitor with domestic livestock (3) (4) (6) (9). Despite these threats, the species still has a wide distribution and large global population (1), and the increasing conversion of forest to grassland, together with management regimes employed on cattle ranches (such as predator control, provision of water, and burning), may even be helping to create more suitable capybara habitat (5) (9). However, some local capybara populations have decreased or even disappeared where hunting pressure is intense, such as near human settlement and along rivers, which are the main travel routes of hunters (1) (2) (10).

The capybara occurs in a number of protected areas throughout its range (1), and efforts have been made to control hunting in many areas (9). Despite this, the capybara is still often killed illegally, and capybara meat is commonly found in rural markets throughout Amazonia (9). However, with its fast growth rate, large size, social lifestyle, cheap diet and high reproductive output, the capybara, if properly managed, is believed to be of great potential for sustainable harvest programmes (2) (9). The species is currently hunted commercially in licensed ranches in the Llanos of Venezuela, which has apparently resulted in stabilisation of the local capybara population (3) (5) (9). The capybara is in fact more efficient at digesting plant material than cattle and horses, and ranching this species in its natural habitat provides a viable and more profitable alternative or addition to cattle ranching (3) (9). Additionally, it helps to maintain natural wetlands which may otherwise be drained for cattle (4). It has been suggested that other seasonally flooded savanna areas, such as the Pantanal of Brazil, have the potential for similar schemes for the sustainable management of this remarkable rodent (9).

View information on this species at the UNEP World Conservation Monitoring Centre.

For further information on the capybara, visit:

• BBC Wildlife Finder:
  http://www.bbc.co.uk/nature/species/Capybara

To read more about the conservation of rodent species see:

Lidicker Jr, W.Z. (1989) Rodents: A World Survey of Species of Conservation Concern. IUCN/SSC Rodent Specialist Group, IUCN, Gland. Available at:
http://data.iucn.org/dbtw-wpd/edocs/SSC-OP-004.pdf