Effects of Resource Partitioning on the Population Dynamics and Energy Utilization Strategies of Feral House Mice (Mus Musculus) Populations Under Experimental Field Conditions

Abstract

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 pa- rameters 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 d d and Y Y in decentralized grids exhibited greater survivorship than did d d and Y Y 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 d d and Y Y were found to have similar assimilation efficiencies no matter where they were trapped in the grids. How- ever, animals from peripheral areas in centralized grids exhibited significantly lower assimilation efficiencies than did animals from food-depot locations. Uneven partitioning of food resources, com- pounded by high population density, has a greater depressing effect on population growth and struc- ture than does high density alone.