The Role of Microhabitat in Structuring Desert Rodent Communities

Interspecific competition is thought to be important in determining patterns of resource use and species abundances in natural communities. However, there have been few field tests of competition—based models of community structure. In this study, experiments were conducted with 4 coexisting desert rodent species to see whether competition is a sufficient explanation for their resource use and abundance patterns. Results were consistent with 3 predictions from competition theory. (1) The 4 species differed in their use of a resource, foraging microhabitat, which is potentially limiting to their populations. (2) Each species shifted its use of microhabitats in predicted directions when competitors were removed from or added to outdoor enclosures. (3) Each species was most dense where its preferred microhabitat was abundant, and augmentation of 1 microhabitat led to an increase in the density of the appropriate microhabitat specialist. These results suggest that competition maintains interspecific differences in foraging microhabitat, and that the availability of appropriate microhabitats determines species abundances on a local scale.