Assessing habitat differentiation between coexisting species: The role of spatial scale

Although the importance of spatial scale for understanding habitat selection patterns and processes has long been recognized, little is known about its impact on the identification of habitat differentiation between sympatric species, despite its likely utility in assessing niche partitioning and thus explaining species coexistence. Here we used radio-telemetry data to examine seasonal habitat selection and differentiation by Cabrera (n = 28) and water voles (n = 29) within habitat patches in a highly fragmented landscape, across spatial extents and resolutions. Habitat selection was found for both species at the home-range and core-area scales, tending to be strongest for water and Cabrera voles at coarse and fine spatial resolutions, respectively. Water voles showed higher preference for humid sedge/rush and reed habitats across seasons and spatial scales. Cabrera voles consistently selected tall grass and shrub habitats during the wet season, whereas dry season preference was higher for sedge/rush and tall grass at fine and coarse spatial resolutions, respectively. Niche overlap was highest during the dry season, lowest at the core-area scale, and increased with spatial resolution. These patterns likely reflected the fine-scale, seasonal habitat preferences of the Cabrera vole, which during the dry season increased the use of small sedge/rush patches embedded in larger tall grass meadows, thereby bringing it in closer contact to the humid habitats selected at coarse spatial resolutions by the water vole throughout the year. Overall, this study suggests that spatial scale may critically influence the perception of habitat differentiation between coexisting species. (C) 2011 Elsevier Masson SAS. All rights reserved.