Santa Catarina's Guinea Pig

Found only on the Moleques do Sul Archipelago in southern Brazil, the Santa Catarina's Guinea Pig occupies one of the smallest ranges of any living mammal. These rodents live on just four hectares of land within a tiny island chain formed 8,000 years ago. Visitors to this humid, grassy environment will find a creature roughly 20 to 40 cm long with a cylindrical body and short legs. Unlike its relatives, the species shows no size difference between males and females. They are covered in coarse brown or gray fur that grows longer at the neck, though their ears are bare and they have no tails.

These cavies spend their time grazing on herbaceous vegetation, particularly in a small feeding area of less than one hectare. Their diet consists mainly of grasses like Paspalum vaginatum, which they keep trimmed very short. They rely on surrounding bushes and taller grasses for protection from predators like southern caracaras, yellow-headed caracaras, and chimango caracaras. While they can breed throughout the year, they typically produce only one or two young per litter. The offspring are notably large, reaching up to 24% of the mother's average mass.

With only about 42 individuals estimated to be alive, the Santa Catarina's Guinea Pig faces a precarious future. Because their feeding grounds are so limited, the population can suffer natural die-offs if they overexploit their food sources. They are also highly vulnerable to environmental disturbances or the introduction of invasive species. Although their home is technically a state park, the lack of enforced entry restrictions leaves them exposed to human interference and other external threats.