Temporal Partitioning between Forest-Dwelling Small Rodents in a Mediterranean Deciduous Woodland

SIMPLE SUMMARY: Camera-trapping has been widely used to assess activity rhythms and temporal overlap of different medium- and large-sized mammal species sharing the same habitats. Conversely, this method has been poorly applied to small mammals, which are often difficult to identify at the species level through photos. In our work, we assessed the temporal overlap between two coexisting small rodents in forest environments, Apodemus flavicollis and Clethrionomys glareolus. We collected 124 independent records of A. flavicollis and 67 records of C. glareolus over three years. The former was mostly nocturnal, with activity peaking after midnight, whereas the latter was mostly active at dawn and dusk. In other words, we recorded a limited temporal overlap, thus suggesting a potential for interspecific competition. Intraguild interference competition between A. flavicollis and C. glareolus may play a pivotal role, forcing C. glareolus to be more active in daylight hours, when the more strictly nocturnal A. flavicollis is present. Nocturnal activity of C. glareolus was limited and not influenced by moon phases, whereas A. flavicollis was mostly active in the darkest nights, avoiding bright moonlight nights. ABSTRACT: Temporal partitioning is reported as one of the main strategies adopted by coexisting mammal species to limit interspecific competition and behavioural interference. In the last decades, camera-trapping surveys have provided valuable insights in assessing temporal niche and activity rhythms of medium and large-sized mammalian species. Conversely, this method has been poorly applied to small rodents. In this work we aimed at assessing temporal niche partitioning between two species of forest-dwelling small rodents—Apodemus flavicollis and Clethrionomys glareolus—by means of intensive camera-trapping. Camera traps were placed in areas where previous genetic analyses have confirmed the only presence of A. flavicollis amongst wood mice species, to prevent misinterpretation of records. We collected 124 independent records of A. flavicollis and 67 records of C. glareolus over three years. The former was mostly nocturnal, with activity peaking after midnight, whereas the latter was mostly active at dawn and dusk. Therefore, a limited temporal overlap was observed, confirming the potential for interspecific competition. Intraguild interference competition between A. flavicollis and C. glareolus may play a pivotal role forcing C. glareolus to be more active in daylight hours where, the more strictly nocturnal A. flavicollis is present. Nocturnal activity of C. glareolus was limited and not influenced by moon phases, whereas A. flavicollis was mostly active in the darkest nights, avoiding bright moonlight nights.