The South American rodent that acts like a rabbit but builds like an engineer

Nature · Published 3 October 2026 · Updated 22 October 2026 Swipe more like this →

In short: Viscachas are South American rodents that defy simple categorization. While mountain species resemble long-eared rabbits darting across rocky cliffs, their plains-dwelling cousins are robust, nocturnal burrowers. These animals exhibit complex social behaviors and unique environmental adaptations, ranging from high-altitude survival to the construction of elaborate, multi-chambered underground tunnel systems.

The four species of viscacha belong to the family Chinchillidae, yet they occupy vastly different ecological niches. Mountain viscachas, belonging to the genus Lagidium, are agile, diurnal creatures found in the Andes Mountains at elevations between 4,000 and 5,000 metres. They inhabit harsh, sparsely vegetated rocky outcrops, where they survive on mosses, lichens, and grasses. These rodents are nonaggressive and gregarious, often forming large colonies that rely on high-pitched, birdlike whistles to signal the approach of predators. Unlike their plains counterparts, they are poor diggers, preferring to shelter in deep rock crevices and stony tunnels during the night.

In contrast, the plains viscacha (Lagostomus maximus) is a nocturnal, heavy-bodied rodent that thrives on the Pampas of Argentina, Paraguay, and southeastern Bolivia. Resembling a large guinea pig, this species is a master excavator. It constructs extensive burrow systems known as vizcacheras, which are so complex that they can pose significant hazards to livestock and humans. These animals are known for their distinctive facial markings, including broad black and white stripes that resemble a moustache. They are highly colonial and exhibit a unique habit of decorating their burrow entrances with piles of collected debris, such as bones, sticks, and dung.

The evolutionary history of these rodents remains a subject of intrigue. While mountain viscachas are closely related to chinchillas, the plains viscacha belongs to a separate subfamily, Lagostominae. Fossil evidence for the plains viscacha dates back to the Early Miocene Epoch, between 23.8 million and 20.5 million years ago. Interestingly, while the plains viscacha has a well-documented fossil record, the ancestors of mountain viscachas and chinchillas have yet to be discovered. This divergence in both biology and behavior highlights the remarkable adaptability of these rodents across the diverse South American landscape, from the thin air of the Andes to the sprawling, open grasslands of the lowlands.

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