The plains viscacha looks a lot like a chinchilla, but it’s known for building vast tunnels underground and for producing more than 300 eggs at one time.
Meet the Plains Viscacha: South America’s Underground Rodent Overlord With a Record-Breaking Reproductive Trick
April 21, 2025 — In the sweeping grasslands of southern South America, a chunky rodent called the plains viscacha quietly rules one of the animal kingdom’s most fascinating underground empires — and holds a surprising reproductive world record.
This gregarious cousin of the chinchilla constructs sprawling subterranean burrow systems called vizcacheras, home to up to 50 individuals. These tunnel networks can stretch 10 feet (3 meters) underground, with multiple hidden exits and dark chambers that once intrigued Charles Darwin during his 19th-century explorations.
Social Life Beneath the Soil
Plains viscachas (Lagostomus maximus) live in hierarchical colonies led by a dominant male known as the vizcachón, who stands watch at dusk. If the coast is clear, he gives the signal — and the rest of the colony emerges to forage under the stars.
The name “viscacha” comes from the Quechua word “wisk’acha”, which mimics the squeaky sounds the animal makes. With its large eyes, stiff whiskers, powerful digging claws, and distinctive black facial stripes, the viscacha is a striking mix of cuteness and capability.
A Mammalian Fertility Marvel
But what truly sets this rodent apart is its record-breaking ovulation capacity. According to the Journal of Experimental Zoology – A, a female viscacha can release up to 326 eggs in a single reproductive cycle — the highest ever recorded in any mammal.
Mating occurs underground in autumn, after fierce male competition. Though only two young are typically born after a five-month gestation, the female’s dual ovulation system — both spontaneous and induced — may serve a crucial biological purpose: increasing the chances that only the healthiest eggs are fertilized.
“It’s a reproductive strategy that maximizes quality over quantity — despite the jaw-dropping number of eggs,” researchers noted in the study.
Resilient and Remarkable
Plains viscachas can live up to eight years and are well-adapted to their dry, open habitats. Their combination of complex social systems, evolutionary ingenuity, and reproductive prowess makes them a species well worth watching — and protecting.