Capybaras are the world’s largest living rodent, native to South America. These semi-aquatic mammals spend time near water sources, forming social groups. Their young, called pups or kits, have an accelerated development trajectory compared to many other mammals. The size of an adult capybara hints at the substantial growth rate required from birth to maturity.
Neonatal Weight: The Immediate Answer
A capybara pup enters the world with a large body mass, linked to its advanced developmental state at birth. Newborn capybaras typically weigh between 2.5 and 4.5 pounds (1.1 to 2.0 kilograms). Some observations note an average birth weight of approximately 2.0 kilograms for both male and female pups.
The capybara is a precocial species, meaning its young are born in a mature and mobile condition. Pups are born fully furred, with their eyes open, and possess a full set of teeth. Within hours of birth, the pups are mobile enough to walk, swim, and join the social group, making them highly independent. This readiness sets them apart from the altricial young of smaller rodent species, which are born blind and helpless.
Rapid Growth and Weaning Milestones
The large birth weight is the starting point for a period of rapid development and weight gain. Capybara pups consume solid food, specifically grass, within the first week of life, long before they are fully weaned. This early introduction supplements the mother’s milk, which they continue to suckle for several months. Pups gain weight consistently, with an average daily increase of 50 to 100 grams during their initial growth phase.
Milk remains part of their diet until they are approximately 16 weeks old, when they are considered weaned. The pups’ weight increase during this time is profound. By the time they reach 18 weeks of age, capybara juveniles may weigh as much as 88 pounds (40 kilograms). This rapid acceleration means the young animal achieves a significant fraction of its full adult size in just a few months.
The growth rate continues steadily, although it begins to slow down beyond the juvenile stage. Wild capybaras may reach a weight of around 22 kilograms by one year of age. They reach full physical size and sexual maturity between 18 months and two years old.
Contextualizing Size: The Adult Capybara
The initial birth weight gains context when compared to the massive size of a fully grown adult capybara. Mature individuals typically weigh between 77 and 146 pounds (35 to 66 kilograms). Females are often slightly heavier than males. These animals stand about 20 to 24 inches (50 to 62 centimeters) tall at the shoulder.
A capybara’s overall length can span up to 4.5 feet, giving them a barrel-shaped appearance that distinguishes them from smaller rodents. While the typical weight range is substantial, exceptional individuals have been documented to weigh more than 200 pounds (90 kilograms). This maximum size emphasizes the enormous scale of the growth achieved from the small, 4-pound pup stage. The final adult dimensions underscore the unique position the capybara holds within the world’s rodent population.