The mara, or Patagonian cavy, is a large rodent related to the guinea pig, but it looks more like a small deer or antelope. Unique to the arid areas of Argentina, Patagonian cavies are monogamous, forming pairs that endure until the death of one of the partners. For protection from predators, they often form communal dens, where pups of more than 20 pairs are kept together.
This unique species is found only in arid areas of Argentina. Sheep, goats, and the introduced European hare have overgrazed their habitat, compete with them for food, and expose them to diseases and parasites.