Scaling body mass and use of space in three species of marsupials in the Atlantic Forest of Brazil

Abstract Body mass is considered a major determinant of home range size, but usually at a large scale of body mass variation. The exact scale where body size becomes more important than particular adaptations of each species is not clear, and uncertainty in the estimate of home range size is a possible cause of weak intraspecific scaling. We determine the scaling to body mass of two alternative movement measurements, daily home range (DHR) and its intensity of use (IU), in three species of didelphid marsupials, Didelphis aurita, Philander frenatus, and Metachirus nudicaudatus (Didelphimorphia, Didelphidae). The expected scaling exponents DHR ≈ M^0.5 and IU ≈ M^?0.25 were derived from the scaling to body mass of home range and daily movement distance. Animals were tracked in Serra dos Órgãos, Rio de Janeiro, Brazil, using a spool‐and‐line device. Individuals of the three species were compared combining intra and interspecific variation in a single analysis, with species, body mass, and thread tracked as covariates. The model best supported included only body mass as the independent variable, with DHR ≈ M^0.435 and IU ≈ M^?0.218, close to the expected values. The second best supported model included species identity, but with a non‐significant effect. It was surprising that body mass was more important than species identity in a comparison involving only three species, and considering the morphological and locomotory adaptations of the three species. Body mass may become more important than species identity when the scale of variation approaches one order of magnitude.