The capybara (Hydrochoerus hydrochaeris), sometimes referred to by the regional name “Chigua” or “Chigüiro,” is the largest living rodent species in the world. Its massive size sets it apart from smaller relatives, such as the guinea pig. The life of this unique mammal is defined by its strong connection to water.
Identity of the Chigua: The World’s Largest Rodent
The capybara has a barrel-shaped body, a blunt snout, and lacks a discernible tail. Adults stand 1.6 to 2 feet tall at the shoulder and measure 3.2 to 4.4 feet in length. Weight generally ranges from 77 to 174 pounds, with females typically being slightly larger than males. Its coarse, reddish-brown fur is sparsely distributed, necessitating frequent dips in water for hydration and thermoregulation. This thin coat also dries quickly, benefiting the semi-aquatic mammal.
As a dedicated herbivore, the capybara consumes up to eight pounds of grasses and aquatic plants daily. This fibrous diet requires a specialized digestive process, including coprophagy—consuming its own feces to extract maximum nutrients and beneficial bacteria. Its dental structure features large, continuously growing incisors necessary to counteract the constant wear from grinding tough plant material. Capybaras inhabit the wetlands, savannas, and dense forests of nearly all South American countries, excluding Chile, always requiring proximity to permanent water sources.
Adaptation to Water: A Semi-Aquatic Lifestyle
Life for the capybara is inseparable from water, which serves as a refuge and a social hub. This semi-aquatic lifestyle is facilitated by specific physical features. The feet are partially webbed, providing the necessary propulsion and maneuverability to move quickly through rivers and marshlands. They achieve agility in the water by paddling with their feet and using a serpentine body motion.
A remarkable physical adaptation involves the placement of the sensory organs: the eyes, ears, and nostrils are situated high on the head. This allows the capybara to remain almost entirely submerged while maintaining awareness of its surroundings, a posture nicknamed “submarine mode.” When danger approaches, the animal can dive and hold its breath for up to five minutes.
Behaviorally, water is utilized for temperature control, as the capybara’s thin fur and dry skin make it susceptible to overheating in the tropical sun. During the hottest parts of the day, individuals wallow in mud or shallow water to keep cool, emerging later in the afternoon or evening to graze. Their home ranges are always located near permanent bodies of water.
Group Dynamics and Social Behavior
Capybaras are highly social mammals, typically living in structured family groups or herds that offer mutual protection and enhanced foraging efficiency. Group sizes usually hover around 10 to 20 individuals, consisting of several adult females, their offspring, and one dominant male. During the dry season, when water sources dwindle, these groups may aggregate into larger herds of 50 or more individuals.
The social hierarchy is maintained through a sophisticated system of communication involving both vocalizations and chemical signals. They produce a variety of sounds, including purrs and clicks for reassurance during social grooming, and whistles used by young animals. When a threat is perceived, a distinct, dog-like bark serves as an alarm call, prompting the group to rush toward the nearest water body.
The social structure is dynamic, with the dominant male regularly asserting his position to maintain order and reproductive exclusivity. Subordinate males and females also maintain a hierarchy, ensuring resources are distributed effectively. Solitary capybaras are rarely observed and have significantly lower survival rates.
Chemical communication relies on specialized scent glands to convey identity, status, and territorial boundaries. The morrillo gland, a raised patch on the male’s snout, secretes an oily substance used for marking objects and females. A larger morrillo often signals a higher social status. Both sexes also possess anal glands, which secrete a unique chemical blend that acts as an olfactory “fingerprint” for individual recognition and territorial marking.
Ecological Role and Conservation Status
The capybara functions as a significant herbivore within South American wetland ecosystems, impacting vegetation growth and structure. By consuming large quantities of grasses and aquatic plants, the species helps maintain open spaces, which benefits other wildlife. This role as an “ecosystem engineer” is important for the overall health of their environment.
Their large size and abundance also make them a significant food source for the region’s apex predators, including jaguars, large anacondas, and caimans. Capybaras frequently exhibit commensal relationships, allowing various birds to perch on their backs to forage for parasitic insects. They often tolerate the presence of multiple different species in close proximity.
The conservation status of the capybara is currently classified as Least Concern by the International Union for Conservation of Nature (IUCN). Their population is stable across most of their range due to their adaptability and ability to reproduce quickly. Localized threats exist from habitat degradation due to agriculture and urbanization, as well as hunting for their meat and hides in some regions.