Resource availability and reproductive activity can exert contrasting demands on movements of promiscuous or polygynous mammals. Movements of the black-eared opossum (Didelphis aurita) vary seasonally in the Atlantic Rainforest of Brazil, so our objectives were to test the relative importance of reproductive activity and resource abundance on movement areas and intensity of use by opossums. We used a spool-and-line device to map the path of individuals, to estimate daily movement areas, and to measure intensity of habitat use. Two models were compared by generalized linear models, by grouping movements by reproductive or climatic season. Males used larger areas less intensively in the breeding season, whereas the movement of females did not differ between breeding and nonbreeding season. Differences between movements of females were significant only when grouped by climatic seasons, with females using larger areas less intensively in the dry season. Movements of females were determined by resource availability, whereas movements of males were determined by reproductive season.