As a common species with a wide range and a stable population, the International Union for Conservation of Nature has rated this rodent as being of "least concern".

The fur on the back is buff with fine pale brown and black lines, the greyish base of the hairs sometimes being visible.

This is a mountain species native to southern South America; its range extends from northern Chile and northwestern Argentina to about 50°S in Patagonia.

[6] Such increases in rodent numbers are the result of greater fecundity, a higher survival of juveniles and a lengthening of the breeding season.

Since many of the bamboo seeds were retained within the flowering spikelets till the following year, further rodent population peaks occurred then.

Their appearance at such a high density was the result of an aperiodic outbreak in the Andes, and living specimens that were caught in traps showed no signs of being in breeding condition.

[7] O. longicaudatus is the principal reservoir host of Andes virus (ANDV), which causes most cases of hantavirus cardiopulmonary syndrome in South America.