Habitat structure may have a significant influence on the occurrence, abundance, and activity patterns of forest mammals. However, anthropogenic habitat disturbance changes habitat structure, which may alter those patterns of activity. We assessed occurrence, relative abundance, and activity patterns of Dromiciops gliroides, an arboreal marsupial endemic to the temperate rainforests of southern South America, contrasting four forest conditions at a regional scale: old-growth, second-growth, and logged forests, and abandoned exotic plantations. We conducted a camera-trap assessment in two consecutive austral summers across most of the Chilean range of D. gliroides, and compared habitat structure along a disturbance gradient. All structural features assessed differed among forest conditions. Dromiciops gliroides was present in all forest conditions, but its abundance decreased and activity got narrower as disturbance increased, being significantly lower in the exotic plantations. Activity patterns were variable among forest conditions and months, and were significantly more restricted temporally at exotic plantations. Although D. gliroides is tolerant to habitat disturbance, we show that structural alteration results in lower abundances and narrower activity patterns.