Eight 0.1—ha small—mammal enclosures were stocked with house mice (Mus musculus) on 6 June 1975. Mice were allowed to populate all grids until late December 1975. Four of the grids contained a centralized food (corn) depot while the other 4 contained equally spaced decentralized depots. Peak densities were reached in all populations by 1 November 1975. Populations in centralized grids reached a mean peak density of °20 animals per grid while the mean peak density in the decentralized grid populations was °30 animals per grid. Decreases in the following population parameters were found in both grid types with increased population densities: reproduction, juvenile mortality, population growth rates, and average cohort weights at first month of trapping. The ♂ ♂ and ♂ ♂ in decentralized grids exhibited greater survivorship than did ♂ ♂ and ♀ ♀ in centralized grids, respectively. Corn consumption was greatest in all grids after mid—October. Animals in the decentralized grids utilized a greater percent of corn to fulfill their energetic requirements than did animals in the centralized grids throughout the study. In the decentralized grids ♂ ♂ and ♀ ♀ were found to have similar assimilation efficiencies no matter where they were trapped in the grids. However, animals from peripheral areas in centralized grids exhibited significantly lower assimilation efficiencies than did animals from food—depot locations. Uneven partitioning of food resources, compounded by high population density, has a greater depression effect on population growth and structure than does high density alone.

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