Patterns of Habitat Utilization in Sympatric Rodents on the Texas Coastal Prairie

Abstract

Habitat utilization by Sigmodon hispidus, Reithrodontomys fulvescens, and Oryzomys palustris was compared to habitat availability, by determining if capture locations were random samples of the trapping grid with respect to mean cover of 10 plant species. A methodology, designed for this purpose and detailed in a companion paper (Kincaid and Bryant 1983), was used in which the Euclidean distance between mean vectors representing habitat utilization and availability was compared to that for random draws from the available resource spectrum. This distance (the habitat differential) was partitioned into separate components representing differential composition and dif- ferential productivity in the occupied habitats. Interspecies differences in habitat utilization were also considered relative to habitat availability. Each species utilized a habitat subset that differed significantly from the average available habitat. Sigmodon and Reithrodontomys were the most similar species, differing only in the pattern of their associations with grasses and cover. Oryzomys usually occurred in habitats dominated by dicots. Deviations for all species were usually attributable to differential composition, except for Sigmodon and Reithrodlontomvs in winter, when both exhibited significant productivity components. Habitats occupied by these rodents were significantly less heterogeneous than random subsets, but only Ory- zomys habitat always had reduced dimensionality of variation relative to that of the available habitat. Differential responsiveness to patterns of statistical variation in a patchy environment can be sufficient to produce habitat separation and is offered as a neutral model for the examination of higher-order processes.