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The Lesser Capybara, Hydrochoerus isthmius. This species of capybara is less well-known then the larger, and much more numerous, Hydrochoerus hydrochaeris. 您知道水豚有2種嗎?這是較小的,數量少得多. カピバラには2種類あることをご存知ですか?この種は小さく、はるかに少ないです

There are 2 species of capybara, the larger Hydrochoerus hydrochaeris, which is the species we all know well, and Hydrochoerus isthmius also called the The Lesser Capybara. The 2 species look very similar. However, the Lesser capybara is smaller, with thicker and wider frontal bones. They have a slightly more angular head and a somewhat darker, brown coloured coat. The Lesser capybara weighs about 28 kg as against 40 – 60 kg for Hydrochoerus hydrochaeris. The 2 species of the genus Hydrochoerus live in habitats which rarely overlap.

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For an interval in the 20th century, the Lesser capybara, Hydrochoerus isthmius , was thought to be a subspecies of the larger Hydrochoerus hydrochaeris. However, genetic studies and studies of their anatomy in the mid-1980s, showed that the Lesser capybara was indeed a separate species. It’s karyotype (genetic sequence) has 2N equals 64 and FN equals 104. The karyotype of the larger Hydrochoerus hydrochaeris is: 2N equals 66 and FN equals 102.

The Lesser capybara breeds throughout the year and gives birth to 3 – 4 pups on average, as against up to 8 pups for Hydrochoerus hydrochaeris. The gestation period is 108 days for the Lesser capybara as against 150.6 days for Hydrochoerus hydrochaeris. The Lesser capybara pups at birth weigh about 1.1 kg (as against 1.5 kg for the larger capybara, Hydrochoerus hydrochaeris). As with Hydrochoerus hydrochaeris, the Lesser capybara can be diurnal or nocturnal, and social or solitary, depending on the season, the habitat and the pressure imposed by hunting.

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There is not a great deal of information about the Lesser capybara, Hydrochoerus isthmius, as relatively few studies of this species have been done. Their conservation status is not known but they may be under threat in some of their traditional habitats. Their numbers are far smaller than Hydrochoerus hydrochaeris, the larger, well-known capybara. Their population status and current distribution in Colombia is unknown.

The Lesser capybara is under threat due to subsistence hunting and the destruction of its habitat. The gallery forests where they live are being cleared and the swamp lands, vital for this semiaquatic species, are being drained. The drainage of the swamp areas bordering the Magdalena River are having a particularly detrimental effect on their numbers.

Predators include jaguars and pumas on land and Cayman in water. Additionally, young capybaras are often attacked by snakes (boa constrictors), crab eating foxes, some birds like the caracara and black vultures.

The Lesser capybara is found in the Caribbean region, the northern end of the Pacific region and the inter-Andean valleys of the Cauca and Magdalena rivers.

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If you want to meet a member of this species, this is where you might be able to find them: The Lesser capybara, Hydrochoerus isthmius, is found to the west of the Andes in Panama, Colombia and Venezuela. The larger, and much more well-known species, Hydrochoerus hydrochaeris, is found in every country in South America except Chile. In these other South American countries, Hydrochoerus hydrochaeris is only found to the east of the Andes, from Venezuela in the North to the mouth of the River Plate, in Argentina. The Lesser capybara is found in Panama and this is the only country in Central America where capybaras live. Both species of capybara can be found in Colombia but the habitats in which they live are separated by the Andes; the Lesser capybara lives west of the Andes and the larger Hydrochoerus hydrochaeris lives east of the Andes. The Lesser capybara is found in northern parts of Colombia, along the Caribbean coast, the lowland headwaters of several rivers including the Catatumbo river, and the rivers to the north and west of the Sierra Nevada De Santa Marta. The Lesser capybara is also found in some valleys and in the Department of Choco. In Colombia the species is known as ponche or caco culopando, lancha and piropiro among other names. Populations of capybara in Colombia are thought to be small but there is little information available. Venezuela is the only other country where both species of capybara are found. In Venezuela, the Lesser capybara is only found around Lago de Maracaibo in Zulia state, west of the Andes. In Venezuela, as in Colombia, the 2 species of capybara are separated from each other by the Andes mountains. The 2 species are not sympatric, meaning they do not live in the same or in overlapping geographical areas.

Both species live in the same type of habitat: a wide variety of lowland habitats with access to ponds, lakes, rivers, swamps, streams or reservoirs. These habitats include gallery forests, seasonally flooded savannas and wetlands. The highest elevation where capybaras, only the larger Hydrochoerus hydrochaeris, have been found is 1500 meters in the Chapada dos Veadeiros National Park in Goias State in Brazil.

(A gallery forest is where the forested area forms a thin ribbon of trees, only a few meters wide, along a riverbank or bounding a wetland area. The surrounding area, moving away from the river or wetlands, is primarily grassland with at most a sparse scattering of trees. These gallery forests are able to exist because they draw water from the rivers. The extent of gallery forest are diminishing as a result of human activities.)

Like their larger relations, the Lesser capybara, Hydrochoerus isthmius, is semiaquatic and usually most active during the afternoon and at night to avoid predators. Capybaras have subcutaneous sweat glands which are sparsely distributed throughout the body, meaning that their ability to sweat is not well developed, so in order to control their body temperature (thermoregulate) in the heat of the day, capybaras rest in water or under the shade of trees and bushes. Capybaras also use water to escape from predators, and they prefer to mate in water. Water is also the source of their preferred aquatic plants, an important part of the capybara diet.

Capybaras tend to rest in the morning and then escape the heat of the day, in the early afternoon, by resting in water. The herd then grazes, on and off, from late afternoon until dawn. The capybara is a highly gregarious and social animal, most often found in family groups. These groups may be as small as a male capybara and one or 2 females, or larger groups of related females and a dominant male. There may also be 1 or 2 subordinate males, who are tolerated by the dominant male, because they stay on the periphery of the herd and act as lookout. Subordinate males emit the highest number of warning calls to alert the herd to possible danger. These subordinate males do mate, and the aggregate number of their matings may exceed that of the dominant male, but overall the dominant male mates the most. Female capybaras often prefer to be mated by the dominant male, so if a subordinate male is mating with her, she will often cry out, to alert the dominant male as to what is happening, so that he can come over and drive the subordinate male away. Female capybaras will also spent more time running away from, and alluding, a subordinate male who is trying to mate with them, than when a dominant male is chasing them to mate.

Capybaras are a sedentary species whose home range may extend from 5 – 16 hectares, depending on the amount of grazing available. This home range will include a large area of grassland, as grasses (and aquatic grasses) form the major part of the capybara diet, an area of slightly elevated dry land for resting, and a permanent body of water. Capybaras also live in forested/jungle habitats beside a river. In these forested habitats the family group usually consists of one male and 1 or 2 females. The Lesser capybara also eats algae.

There have been no studies indicating that interbreeding between the 2 species of capybara has taken place. However, in Colombia some capybaras of the larger species, Hydrochoerus hydrochaeris, were taken from the Orinoco River region to recreational houses in the Cauca Valley, from where they escaped into rivers and wetland areas.

Encounters between 2 species of the same genus can lead to hybridisation which may have detrimental effects on hybrid descendants. If these encounters are extensive it may result in the local extinction of both parental species. There is no evidence that this has or could happen to these 2 species of capybara, Hydrochoerus hydrochaeris and Hydrochoerus isthmius.

Scientific classification:

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Rodentia

Family Caviidae

Genus Hydrochoerus

Species Hydrochoerus isthmius

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