Their social organizations have a unique combination of monogamy and communal breeding.
Being monogamous, pairs of maras stay together for life, with replacement of partners only occurring after one's death.
The male has almost the sole responsibility in maintaining the pair by following the female wherever she goes.
A male marks his female with urine and marks the ground around her with secretions from his glands and with feces, making the grounds around the female a mobile territory.
Pairs breed together alone or with other pairs in warrens shared by up to 29 pairs.
Maras breed, at least in southern Argentina, from August to January.
Gestation lasts 100 days in wild.
 Most births in Patagonia occur between September and October, which is before the summer dry season and after the winter rains.
Females produce one litter each year in the wild, but can produce as many as four litters a year in captivity.
Young can walk almost immediately postpartum.

Dens are dug during the breeding season for the young to be raised.
Litters from one to 22 pairs are grouped together in these dens.
Communal living provides protection from predators with the survival rate for young being higher in larger groups than in smaller groups.
One pair visits the den at a time for around one hour and the other parents  circle around the den.
One or two  pups are nursed at a time by a female.
A female may sometimes nurse a young from another pair.
While a female may prevent young other than her own from nursing her, some young are able to steal milk.
Mothers do not actively cooperate in raising their young.
 For the first three weeks, young remain near the den.
At this time, distance between individuals is low, with frequent body contact, huddling, allogrooming, and extended play among the pups.
 After this, the young are able to leave the den and graze with their parents.
Young are weaned after 13 weeks.

Maras make a number of vocalizations during grazing or slow locomotion.
When seeking contact, a mara emits an inflected "wheet" while a low, repetitive grunt is made when following a conspecific.
Maras tooth chatter and emit low grunts when threatened.
They also produce a series of short grunts when grooming.
Scent marking is used by maras for complex and intense social interactions.
Maras stretch and sniff the soil and then sit upright with an arched back and the anogenital area flattened to the ground,  a process known as anal digging.
 In addition, a male stands on his hind legs and urinates on a female's rump, to which the female responds by spraying a jet of urine backwards into the face of the male.
The male's urination is meant to repel other males from his partner, while the female's urination is a rejection of any approaching male when she is not receptive.
Both anal digging and urination are more frequent during the breeding season and are more commonly done by males.
Their social organizations have a unique combination of monogamy and communal breeding. Being monogamous, pairs of maras stay together for life, with replacement of partners only occurring after one's death. The male has almost the sole responsibility in maintaining the pair by following the female wherever she goes. A male marks his female with urine and marks the ground around her with secretions from his glands and with feces, making the grounds around the female a mobile territory. Pairs breed together alone or with other pairs in warrens shared by up to 29 pairs. Maras breed, at least in southern Argentina, from August to January. Gestation lasts 100 days in wild.  Most births in Patagonia occur between September and October, which is before the summer dry season and after the winter rains. Females produce one litter each year in the wild, but can produce as many as four litters a year in captivity. Young can walk almost immediately postpartum. 
Dens are dug during the breeding season for the young to be raised. Litters from one to 22 pairs are grouped together in these dens. Communal living provides protection from predators with the survival rate for young being higher in larger groups than in smaller groups. One pair visits the den at a time for around one hour and the other parents  circle around the den. One or two  pups are nursed at a time by a female. A female may sometimes nurse a young from another pair. While a female may prevent young other than her own from nursing her, some young are able to steal milk. Mothers do not actively cooperate in raising their young.  For the first three weeks, young remain near the den. At this time, distance between individuals is low, with frequent body contact, huddling, allogrooming, and extended play among the pups.  After this, the young are able to leave the den and graze with their parents. Young are weaned after 13 weeks.
Maras make a number of vocalizations during grazing or slow locomotion. When seeking contact, a mara emits an inflected "wheet" while a low, repetitive grunt is made when following a conspecific. Maras tooth chatter and emit low grunts when threatened. They also produce a series of short grunts when grooming. Scent marking is used by maras for complex and intense social interactions. Maras stretch and sniff the soil and then sit upright with an arched back and the anogenital area flattened to the ground,  a process known as anal digging.  In addition, a male stands on his hind legs and urinates on a female's rump, to which the female responds by spraying a jet of urine backwards into the face of the male. The male's urination is meant to repel other males from his partner, while the female's urination is a rejection of any approaching male when she is not receptive. Both anal digging and urination are more frequent during the breeding season and are more commonly done by males.
Patagonian mara