The Capybara (Hydrochoerus hydrochaeris)

May 22, 2011 Features / Columnists, Interesting Creatures in Guyana

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The capybara (Hydrochoerus hydrochaeris), also known as capibara, chigüire in Venezuela, Colombia, and Ecuador ronsoco in Peru, chigüiro, and carpincho in Spanish and capivara in Portuguese, is the largest living rodent in the world.  Its closest relatives are agouti, chinchillas, coyphillas, and guinea pigs.
Capybaras have heavy, barrel-shaped bodies and short heads with reddish-brown fur on the upper part of their body that turns yellowish-brown underneath. Adult capybaras may grow to 130 centimetres (4.3 ft) in length, and weigh up to 65 kg (140 lb). The top recorded weight is 105.4 kg (232 lbs). Capybaras have slightly webbed feet, no tail and 20 teeth. Their back legs are slightly longer than their front legs and their muzzles are blunt with eyes, nostrils, and ears on top of their head. Females are slightly heavier than males. Females average 36 to 66 kg (80 to 145 pounds), while males typically weigh about 34 to 61 kilograms (75 to 135 pounds).
Capybaras are semi-aquatic mammals found wild in much of South America (including Colombia, Ecuador, Bolivia, Venezuela, Brazil, Argentina, Guyana, Suriname, French Guiana, Uruguay, Peru, and Paraguay) in densely forested areas near bodies of water, such as lakes, rivers, swamps, ponds and marshes, as well as flooded savannah and along rivers in tropical forest. They roam in home ranges of 25–50 acres (10–20 ha).
Many escapees from captivity can also be found in similar watery habitats around the world. Sightings are fairly common in Florida, although a breeding population has not yet been confirmed. Though it has been erroneously stated that a population of capybara existed in the River Arno in Florence, Italy, this was determined to be the nutria or coypu (Myocastor coypus), a considerably smaller South American aquatic rodent with a similar appearance.
Capybaras are herbivores, grazing mainly on grasses and aquatic plants, as well as fruit and tree bark. An adult capybara will eat 6 to 8 pounds (2.7 to 3.6 kg) of grasses per day.  Capybaras are very selective feeders with four to six plant species making 75% of its diet. They will select the leaves of one species and disregard other species surrounding it. Capybaras eat an even greater variety of plants during the dry season as there are fewer plants available. While they eat grass during the wet season, they have to switch to reeds during the dry season as they are more abundant. Plants that capybaras eat during the summer lose their nutritional value in the winter and they are thus not consumed at that time.
The capybara’s jaw hinge is non-perpendicular and they thus chew food by grinding back and forth rather than side-to-side. Capybaras are coprophagous, meaning they eat their own feces as a source of bacterial gut flora and to help digest the cellulose in the grass that forms their normal diet and extract the maximum protein from their food. They may also regurgitate food to masticate again, similar to cud-chewing by a cow.
Like its cousin the guinea pig, the capybara does not have the capacity to synthesize vitamin C, and capybaras un-supplemented with vitamin C in captivity have been reported to develop gum disease as a sign of scurvy. They can have a life span of 8-10 years in the wild but average a life less than four years as they are “a favourite food of jaguar, puma, ocelot, eagle and caiman”. The capybara is the preferred prey of the anaconda.
Capybaras are very gregarious. While they do sometimes live solitarily they are more commonly found in groups that average 10-20 individuals. With 2-4 of them being adult males, 4-7 being adult females, and the rest being 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 are organized in stable, linear hierarchies. The dominant male in each group is significantly heavier than any of the subordinates, but among subordinates, status is not correlated with weight.
The dominant male is positioned in the centre of the group while subordinates are on the periphery. These hierarchies are established early in life among the young with play fights and mock copulations. The most dominant males have access to the best resources.
Capybaras are very vocal and, when in groups, chatter with each other to establish social bonds, dominance or general group census. They can make a dog-like bark which is made when the animals are threatened or when females are herding young. The bark of a capybara is often mistaken for that of a dog.
Capybara have two different scent glands; a morillo, located on the snout, and an anal gland. Both sexes have those glands but males have larger morillos and their anal pockets can open more easily. 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 like plants. These hairs have a longer lasting scent mark and are tasted by other capybaras.
A capybara marks by rubbing its morillo on an object or by walking over a scrub and marking with its anal gland. A cabypara can spread its scent further by urinating. However, females usually mark without urinating and mark less frequently than males overall. Females mark more often during the wet season when they are in estrus. In addition to objects, males will also mark females.
When in estrus, the female’s scent changes subtly and nearby males begin pursuit. In addition, a female will alert males that she is in estrus by emitting a whistling noise though her nostrils. During mating, the female has the advantage and mating choice. Capybaras mate only in the water and if a female does not want to mate with a certain male she will either submerge or leave the water. Dominant males are highly protective of the females, however they usually can’t prevent all 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 usually produces a litter of four capybara babies, but may produce between two and eight in a single litter. Birth is on land and the female will rejoin the group within a few hours of delivering the newborn capybaras, who will join the group as soon as they are mobile.
Within a week the young can eat grass, but will continue to suckle – from any female in the group – until weaned at about 16 weeks. Youngsters will form a group within the main group. Alloparenting has been observed in this species. The rainy season of April and May marks the peak breeding season.
Like other rodents, the front teeth of capybaras grow continually to compensate for the constant wearing-down from eating grasses; their cheek teeth also grow continuously. When fully grown, a capybara will have coarse hair that is sparsely spread over their skin, making the capybara prone to sunburn. To prevent this, they may roll in mud to protect their skin from the sun.
(Source: Wikipedia – The Free Online Encyclopedia)

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