Variation in habitat use of coexisting rodent species in a tropical dry deciduous forest

Abstract

Use of habitat is a critical component related to structure of small-mammal communities, with partitioning occurring primarily along dimensions of microhabitat, although use of microhabitat often does not explain fully use at a macrohabitat level. Through grid studies of small mammals in coastal Colima, Mexico (during January 2003-2005), we appraised influence of available habitat, species richness, abundance, and cumulative abundance of other small mammals on variation in habitat used by species. We evaluated 14 habitat variables (reflecting ground cover, slope, canopy, and vegetation density on vertical and horizontal axes) and developed a composite variable (principal component 1) reflecting general openness of habitat through which we addressed habitat use. For the four most common mammalian species (. Sigmodon mascotensis, . Heteromys pictus, . Baiomys musculus, and . Oryzomys couesi), two measures of variation in habitat used were employed to estimate niche breadth, one of which assessed variation in habitat use relative to variation present on a grid. . Sigmodon mascotensis and . B. musculus preferred areas that were more open, and . H. pictus and . O. couesi occupied less-open areas; breadth of habitat use did not differ interspecifically. Habitat use was more variable on grids with more variability in habitat, although not greater than chance expectations. Findings do not lend support to the resource-breadth hypothesis as an explanation for population densities of species at a local level or the habitat-heterogeneity hypothesis as a predictor of species richness. Variation in habitat used by . S. mascotensis did not proportionally increase when diverse habitat was available but was greater when the species was more abundant. For . H. pictus, when cumulative abundance of other small mammals was greater, breadth of habitat used was greater. Intraspecific density-dependent habitat selection may result in . S. mascotensis selecting a greater variety of habitats, while greater interspecific abundance is related to a greater range in use of habitats by . H. pictus. . Baiomys musculus used a higher proportion of habitat relative to that available when more species were present on a grid. Variation in habitat used by . O. couesi was unrelated to any factor examined. Overall, the four species responded in notably different ways with respect to availability of habitat, abundance, and presence of other species. © 2012 Deutsche Gesellschaft für Säugetierkunde.