It is found in high-Andean puna vegetation. It can be found in both primary and secondary habitat. It is crepuscular and diurnal. This rodent is found on sandy and gravely soils, usually on slopes. Burrow systems usually consist of a single main tunnel from which short lateral branches diverge every few meters and include one or more chambers with stored vegetation and other chambers with nests. Only one animal lives in each burrow system. The burrows are expanded as vegetation is eaten and C. opimus reveals its presence by stripping large areas of natural vegetation. It eats roots, stems, or leaves of most of the available plants. The species digs a tunnel to the food source, then forages no more than two to thee body lengths outside its burrows, bringing the food back to the hole to eat (Pearson 1951, 1959; Pine et al. 1979; Tamayo and Frassinetti 1980; Mares et al. 1981; Eisenberg and Redford 1999).

This species occurs in northwest Argentina, southwestern Bolivia, southern Peru, northern Chile, between 2,500 and 5,000 m asl on the Andean steppe.

It may be present in a number of protected areas. Further general research is needed into this species.