Chacoan Mara

Fascinating facts about the Chacoan Mara

• A rodent that weighs as much as a small dog — up to 16 kg — the Chacoan mara is the second-largest living rodent on Earth, built like a long-legged deer with the teeth of a guinea pig. This body plan is a survival formula: the extended legs let it sprint across open grassland at 45 km/h to escape jaguars and pumas, while its high-crowned molars never stop growing to handle a diet of tough, silica-laden grasses that would wear down ordinary teeth in months.
• Chacoan maras form lifelong pair bonds with a single mate — a rarity in rodents — and stay together for decades, foraging side by side and sleeping in the same burrow. When a pair has young, both parents stand guard at the burrow entrance, taking turns as sentries to watch for predators while the other feeds. This monogamous devotion reveals that rodents, often dismissed as solitary animals, can build relationships as structured as many primates.
• They are born fully furred and with eyes open, ready to follow their mother into the grassland within hours — a level of development so advanced that newborn maras are more 'ready' at birth than a human infant at 9 months old. This acceleration comes at a cost: the Chacoan mara's pregnancy lasts 77 days, nearly three times longer than a house mouse's, trading litter size for offspring competence.
• In the Gran Chaco — a vast scrubland shared by Argentina, Paraguay, and Bolivia where temperatures swing from freezing to 45°C — the Chacoan mara has no need to drink water directly. It extracts all the moisture it needs from vegetation, a water-conservation strategy so efficient that it can vanish underground for drought months in torpor-like states, slowing its metabolism to wait out the dry season.
• Chacoan maras are a keystone prey species that sustains some of South America's rarest apex predators: puma, jaguar, and the near-extinct giant otter populations that venture inland. Loss of mara habitat in the Gran Chaco ripples outward, starving apex predators that have nowhere else to hunt. Protecting grassland for a rodent the size of a rabbit may be the difference between a jaguar population surviving or collapsing.

At a glance

About the Chacoan Mara

In the arid expanses of the Chaco, a large and gentle soul roams, the Chacoan Mara, its powerful hind legs propelling it with effortless ease across the dusty terrain, its large ears twitching with every subtle sound. As it moves, its soft brown coat blends seamlessly into the surrounding landscape, allowing it to vanish and reappear with an air of quiet mystery. With its unique blend of rabbit-like agility and deer-like gentleness, the Chacoan Mara is a remarkable creature, well adapted to the harsh yet beautiful world it inhabits.

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