Ecology and Population Structure of Two Sympatric Rodents in a Neotropical Forest of Southeastern Brazil

Rodents are the most diverse group of mammals, yet the natural history of many species remains poorly understood due to their elusive behavior. In this study, we examined the population structure, home range, space use, and food selection of two sympatric sigmodontine rodents, <i>Euryoryzomys russatus</i> and <i>Sooretamys angouya</i>, in the Morro Grande Forest Reserve, Brazil. <i>E. russatus</i> was more abundant than <i>S. angouya</i>, with its capture rates influenced by temperature. In contrast, the population variation of <i>S. angouya</i> showed no clear relationship with the assessed biotic (fruits and arthropods) or abiotic factors (temperature and precipitation), suggesting different primary regulatory factors for its population or a more generalist ecological strategy. The two species exhibited vertical stratification in space use: <i>S. angouya</i> displayed scansorial and arboreal locomotion, while <i>E. russatus</i> remained strictly terrestrial. Home range size, space use, and mobility were primarily influenced by resource availability, reproductive cycles, and individual body size. Our findings provide insights into the life strategies of these species, specifically regarding their vertical stratification in space use and their distinct responses to environmental resource fluctuations, enhancing our understanding of how sympatric rodents navigate shared spatial and temporal environments.