The Patagonian mara lives only in the arid regions of central and southern Argentina.
It is a monogamous species, with male-female pairs often bonding for life. The couple bond is maintained by the efforts of the male, who follows and protects the female. Monogamy increases the reproductive success of males by reducing the death rate of their own offspring and by increasing the longevity of their partner, which allows them more opportunities to reproduce. Another benefit of mating is that females can invest more time and attention in caring for their offspring, relying on the male to be vigilant for predators. The female gives birth to 1 or 2 young after 100 days of gestation. Although members of this species spend most of the year in male-female pairs, when the young are born, they gather in large groups around large burrowing "settlements" and care for the young in communal nurseries.
The Mara's range is continually shifting as a result of food resources. They only eat the tips of the leaves of the grass, so resources are depleted very quickly and once exhausted it takes up to four months to renew them completely.
Humans now represent the main threat to this species, both from habitat disturbance and poaching.