The world's fourth-largest rodent forms unique communal nurseries where multiple pairs raise young together. Males guard communal crèches while females visit only briefly to nurse their own offspring.
Hugo Hulsberg, CC0, via Wikimedia Commons
A Society of Monogamous Crowd-Dwellers
The Patagonian mara (Dolichotis patagonum), a large rodent endemic to the arid grasslands of Argentina, has a social system that is rare among mammals. They are strictly monogamous, with pairs often bonding for life. This lifelong pairing is maintained by the male, who diligently follows the female, creating a mobile territory around her. He marks this area with urine and glandular secretions to ward off rivals.
Despite this fierce pair-bonding, maras become highly social during the breeding season from August to December. Multiple pairs, sometimes as many as 29, will share a single, large underground den, or crèche, to raise their young. This communal arrangement offers increased protection from predators like foxes and birds of prey. Studies show that the survival rate for pups is higher in these larger groups. A single den can contain an average of 4 breeding adults and their offspring.
The young maras, typically a litter of one to three, are born well-developed with their eyes open. For the first three to four weeks, they remain near the den, where they are very social, huddling and playing with the other pups. This early interaction helps them learn scents and build strength.
Distinct Parental Responsibilities
Within the communal den, parental duties are sharply divided. The male’s role is almost entirely focused on vigilance. He spends the majority of his time scanning for predators, which allows the female more time to forage to meet the high energy demands of pregnancy and lactation. Males rarely interact directly with the pups.
Females, on the other hand, manage all the direct care but their visits to the crèche are brief and infrequent. A mother visits the den only once a day for about an hour to nurse her young. When she arrives, she gives a shrill call that summons all the pups from the burrow. She then identifies her own offspring by their unique scent before leading them a short distance away to suckle. This identification is important, as females will aggressively reject attempts by other pups to steal milk. After about 13 weeks, the young are weaned and can forage with their parents. This combination of monogamy and communal denning is an adaptation to the pressures of life on the open Patagonian steppe.
💡Fun Facts
Patagonian maras are exceptionally fast runners, capable of reaching speeds up to 70 kilometers per hour (about 45 mph).
A female mara's estrus, the brief period when she is receptive to mating, lasts for only 30 minutes and occurs just a few times a year.
When alarmed, maras perform a unique four-legged bounding gait called "stotting," similar to that seen in some antelope species.
The IUCN lists the Patagonian mara as Near Threatened due to habitat loss from agriculture and competition with introduced species like the European hare.
The Península Valdés Nature Reserve is generally accessible year-round. Wildlife viewing is best from September to December.
Admission
An entrance fee is required. The fee varies for foreign visitors and Argentine residents and is paid each time you enter, unless you are staying overnight within the reserve.
Accessibility
The reserve is large with mostly gravel roads. Driving with caution is advised due to wildlife crossings. A private vehicle or organized tour is necessary to explore the area.
