Meet the Viscachas: South America’s Bunny-Like Rodents

In the high Andes, these creatures are usually on sun-warmed rock. These are viscachas, a small group of South American rodents few people know. They might be the most underappreciated rodents in the Western Hemisphere.

There are two types of Viscachas: mountain viscachas that haunt the Andes Mountains, and plains viscachas that tunnel beneath the Pampas grasslands. Both types belong to the chinchilla family (Chinchillidae), making them distant cousins of the fluffy pet chinchillas and more closely related to guinea pigs than to rabbits. Yet through an evolutionary quirk, viscachas ended up looking a lot like rabbits, which is a case of convergent evolution where unrelated animals evolve similar looks and habits.

These rodents have mastered the art of extreme living. Mountain viscachas thrive at altitudes up to 16,000 feet (4,876.8 meters), leaping among barren rocks where few other mammals dare to roam. Down on the lowlands, plains viscachas form big underground colonies, think prairie dogs, but supersized, that can house dozens of family members for generations. The mountain species by day love to stretch out on a boulder and bask in the sun. They also have high-pitched alarm calls to record-breaking fertility, which help them survive and thrive.

Life in the Heights vs. Life on the Plains

Mountain viscachas (genus Lagidium) live high in the Andes from Peru down to Chile and Argentina. There are several species of these alpine rodents, often collectively just called “mountain viscachas” or sometimes “rock viscachas.” They typically weigh a few pounds (up to ~3 kg) and have bodies about 1–1.5 feet long, plus an equally long, curling tail. Their fur is thick and plush to guard against chilly mountain air, usually colored in mottled grays, browns, and reds that blend into the stone. Those big, fluffy ears likely help the viscacha dissipate heat under the high-altitude sun and hear any faint sounds echoing off the rocks. The soles of their feet have special fleshy pads, almost like built-in sneakers, that provide grip on slippery boulders. A mountain viscacha can hop and scramble among rocky cliffs. In fact, all species in the chinchilla family are experts at leaping and climbing, except their lowland cousin, the plains viscacha, which has traded jumping for digging.

Down in the lowlands, the plains viscacha (Lagostomus maximus) is a different beast. Found in Argentina, Paraguay, and a bit of Bolivia, it inhabits flat, open grasslands known as the Pampas. The plains viscachas are equipped for a burrowing life: their front limbs are stout and strong, with long claws on four toes perfect for excavating soil. This species is noticeably larger and heavier than its mountain kin. A full-grown male can weigh up to 8–9 kg (almost 20 lbs), making it one of the heaviest rodents in South America. Its fur is coarser and varies from steely gray to pale brown, often matching the dusty soil of its habitat. Perhaps the most stunning feature is the plains viscacha’s face: both males and females wear bold black-and-white facial stripes, including a unique black streak across the cheeks. (Indeed, males have bushy “moustache” markings paired with stiff whiskers.) This unique face paint makes the species easy to tell apart from any other rodent.

The lifestyles of these two viscacha types are almost opposite. Mountain viscachas are mostly diurnal (active in daylight), bounding around at sunrise and sunset and then sunbathing or snoozing during the middle of the day. When evening comes, they retreat into crevices between rocks that serve as shelters since these viscachas aren’t great diggers. They don’t stray far from their rocky fortresses; at the first sign of danger, a mountain viscacha will dive into a nearby gap or tunnel to hide. In comparison, the plains viscacha is strictly nocturnal, staying safe below ground all day and emerging after dusk to feed under the cover of darkness. In the heat of daylight, a visitor to the Pampas might not see any sign of viscachas at all, but at night, these rodents scurry about in the open, grazing on grasses and whatever plants they can find. By sunrise, they’re back in their extensive burrow systems, which brings us to one of the coolest aspects of viscacha life: their housing situation.

Home Sweet Burrow: The Viscacha “Villages”

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