The continuing studies of interspecific relationships in communities emphasize the importance of environmental complexity and behavioural heterogeneity in determining species distributions and coexistence (for example, Cody 1968; MacArthur 1958; MacArthur & MacArthur 1961; Rosenzweig & Winakur 1969). Patterns of food selection and utilization also are important factors in species coexistence within communities (for example, Lamprey 1963; Rosenzweig & Sterner 1970; Brown & Lieberman 1973; Smigel & Rosenzweig 1974). The studies of MacMillen (1964a) and M'Closkey (1972) of small mammals living in two coastal sage scrub communities near Los Angeles, California have demonstrated the coexistence of up to nine species of rodents. M'Closkey (1972) could find few significant negative correlations in pair-wise comparison of species population trends as might be expected if competition was occurring. Therefore, different mechanisms of habitat and resource utilization probably accounted for the coexistence of these rodent species. This study, conducted in the same community considered by M'Closkey, documents the means by which these species avoided competition.