Behavioral aspects of competition in a three-species rodent guild of coastal southern California

Summary The influence of vole cycles on the demography, spatial organization, and abundance of potential rodent competitors was studied in three California rodents in the laboratory and in the field. Population densities ofMicrotus californicus were inversely correlated with reproductive success in two potential competitors (Reithrodontomys megalotis andMus musculus). Additionally, high-density vole populations forced these species into suboptimal habitats. During low-density vole populations,Reithrodontomys andMus left their refugia, expanded their usage of habitat, were more active, and their reproductive success was greater. Thus, this work suggests that during vole population peaks, competition with sympatric species of mice is severe. Conversely, when vole populations decline, competition is relaxed. The temporal and spatial organization of the three-species complex supports models of nonequilibrium and fugitive species coexistence.