The world's largest rodent, the massive Capybara is more than a meter in length and as heavy as an adult human. As a matter of fact, the word 'capybara' is believed to mean 'master of the grasses', whereas the scientific name of this species means 'water hog' in Greek. This huge animal leads semi-aquatic lifestyle, spending a lot of its time in water. When the animal swims, its nostrils, eyes and short, rounded ears emerge from the water due to being located high on its head. The body of this rodent has neutral buoyancy in water, since it contains a lot of fatty tissue. Males of this species are identified by the prominent, well-developed scent gland on the top of their snout. This area of their body is called 'morillo'. It is dark and naked, producing white and sticky fluid, which is likely to be used in announcing dominance.
The range of capybara covers a huge area, extending over much of South America to the east of the Andes, from Colombia and Venezuela southwards to northern Argentina. Capybara is found in lowland areas with close proximity to water. Preferred habitats include rainforest lakes and rivers, marshes, brackish wetlands, swamps as well as seasonally flooded grasslands and savannas.
Capybaras are social animals, forming family units of 10 - 30 animals, although group size often depends on environment. Thus, during the dry season, when the animals gather at dwindling pools, temporary concentrations of up to 100 individuals can be observed. A typical family group of capybaras consists of one dominant male, one or more subordinate males, one or more related females as well as offspring of different ages. Meanwhile, males tend to be more solitary. Adult individuals of the group participate in defending their territory against outsiders, scent marking their range with secretions from their scent glands. Being crepuscular, capybaras spend the daytime hours resting, being active in the morning and evening. Where capybaras face persecution by humans, they usually tend to be nocturnal. When threatened, these animals are known to flee, either running over land or diving into water.
These animals have polygynous to polygynandrous (promiscuous) mating system, where individuals of both sexes can mate with multiple mates. Dominant males often limit access of other males to females. Both males and females can choose mates. Mating occurs in water. If a female doesn't want to mate with the male, she can dive or come out of the water. Capybaras breed throughout the year with peak period, occurring from May to June, which coincides with the early rainy season. Gestation period lasts for 150 days, yielding a litter of 2 - 8 babies. Offspring of this species are born precocial. After a short while, the babies are able to stand and walk. Within first week of their life, they begin grazing. The mother and other related females of the group suckle the young until weaning, which occurs at 3 months old. After that, young remain in the group of their parents until 1 year old, becoming mature by 12 - 18 months old.
One of the biggest threats to the overall population of this species is hunting. The animals are hunted for their meat and hide. They also attract hunters for grease from, found in their thick and fatty skin, which has pharmaceutical value. Capybaras are considered to be a pest species and killed by farmers, who believe these animals destroy cereal or fruit crops as well as compete with domestic livestock, which isn't true.
According to IUCN, the Capybara is locally common and widespread throughout its range but no overall population estimate is available. Currently, this species is classified as Least Concern (LC) on the IUCN Red List.
In certain parts of their range, these animals are the only large grazers, hugely controlling vegetation of the area. On the other hand, capybaras are a source of food for jaguars, green anacondas, spectacled caimans and other predators of their habitat.