Capybara

(Hydrochoerus hydrochaeris)

The capybara is a large rodent of the genus Hydrochoerus of which the only other extant member is the lesser capybara (Hydrochoerus isthmius). The capybara is the largest rodent in the world. Close relatives are guinea pigs and rock cavies, and it is more distantly related to the agouti, chinchillas, and the coypu. Native to South America, the capybara inhabits savannas and dense forests and lives near bodies of water. It is a highly social species and can be found in groups as large as 100 individuals, but usually lives in groups of 10-20 individuals. The capybara is not a threatenedЬ�Ь�0��8��c�used in the pharmaceutical trade.

Conservation status

Least concern

Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Rodentia
Family:	Caviidae
Genus:	Hydrochoerus
Specie:	Hydrochoerus hydrochaeris

Description

The capybara has a heavy, barrel-shaped body and short head, with reddish-brown fur on the upper part of its body that turns yellowish-brown underneath. Its sweat glands can be found in the surface of the hairy portions of its skin, an unusual trait among rodents. The animal lacks under hair, and guard hair differs little from over hair. Adult capybaras grow to 106 to 134 cm (3.48 to 4.40 ft) in length, stand 50 to 62 cm (20 to 24 in) tall at the withers, and typically weigh 35 to 66 kg (77 to 146 lb), with an average in the Venezuelan llanos of 48.9 kg (108 lb). The top recorded weights are 91 kg (201 lb) for a wild female from Brazil and 73.5 kg (162 lb) for a wild male from Uruguay. The dental formula is 1.0.1.3 . Capybaras have slightly webbed feet and vestigial tails. Their hind legs are slightly longer than their forelegs; they have three toes on their rear feet and four toes on their front feet. Their muzzles are blunt, with nostrils, and the eyes and ears are near the top of their heads. Females are slightly heavier than males.

Diet and predation

Capybaras are herbivores, grazing mainly on grasses and aquatic plants, as well as fruit and tree bark. They are very selective feeders and feed on the leaves of one species and disregard other species surrounding it. They eat a greater variety of plants during the dry season, as fewer plants are available. While they eat grass during the wet season, they have to switch to more abundant reeds during the dry season. Plants that capybaras eat during the summer lose their nutritional value in the winter, so are not consumed at that time. The capybara's jaw hinge is not perpendicular, so they chew food by grinding back-and-forth rather than side-to-side. Capybaras are autocoprophagous, meaning they eat their own feces as a source of bacterial gut flora, to help digest the cellulose in the grass that forms their normal diet, and to extract the maximum protein and vitamins from their food. They may also regurgitate food to masticate again, similar to cud-chewing by cattle. As is the case with other rodents, the front teeth of capybaras grow continually to compensate for the constant wear from eating grasses; their cheek teeth also grow continuously.

Like its relative the guinea pig, the capybara does not have the capacity to synthesize vitamin C, and capybaras not supplemented with vitamin C in captivity have been reported to develop gum disease as a sign of scurvy.

They can have a lifespan of 8-10 years, but live less than four years in the wild, as they are "a favourite food of jaguar, puma, ocelot, eagle, and caiman". The capybara is also the preferred prey of the anaconda.

Social organization

Capybaras are gregarious. While they sometimes live solitarily, they are more commonly found in groups around 10-20 individuals, with two to four adult males, four to seven adult females, and the remainder juveniles. Capybara groups can consist of as many as 50 or 100 individuals during the dry season when the animals gather around available water sources. Males establish social bonds, dominance, or general group census. They can make dog-like barks when threatened or when females are herding young.

Capybaras have two types of scent glands; a morillo, located on the snout, and anal glands. Both sexes have these glands, but males have much larger morillos and use their anal glands more frequently. The anal glands of males are also lined with detachable hairs. A crystalline form of scent secretion is coated on these hairs and is released when in contact with objects such as plants. These hairs have a longer-lasting scent mark and are tasted by other capybaras. Capybaras scent-mark by rubbing their morillos on objects, or by walking over scrub and marking it with their anal glands. Capybaras can spread their scent further by urinating; however, females usually mark without urinating and scent-mark less frequently than males overall. Females mark more often during the wet season when they are in estrus. In addition to objects, males also scent-mark females.

Reproduction

When in estrus, the female's scent changes subtly and nearby males begin pursuit. In addition, a female alerts males she is in estrus by whistling though her nose. During mating, the female has the advantage and mating choice. Capybaras mate only in water, and if a female does not want to mate with a certain male, she either submerges or leaves the water. Dominant males are highly protective of the females, but they usually cannot prevent some of the subordinates from copulating. The larger the group, the harder it is for the male to watch all the females. Dominant males secure significantly more matings than each subordinate, but subordinate males, as a class, are responsible for more matings than each dominant male. The lifespan of the capybara's sperm is longer than that of other rodents.

Capybara gestation is 130-150 days, and produces a litter of four capybara young on average, but may produce between one and eight in a single litter. Birth is on land and the female rejoins the group within a few hours of delivering the newborn capybaras, which join the group as soon as they are mobile. Within a week, the young can eat grass, but continue to suckle-from any female in the group-until weaned around 16 weeks. The young form a group within the main group. Alloparenting has been observed in this species. Breeding peaks between April and May in Venezuela and between October and November in Mato Grosso, Brazil.