A Field Experiment to Examine the Effects of Food Quality and Population Density on Reproduction of Wild House Mice

Abstract

A field experiment, with a 22 factorial design, was conducted on sixteen trapping grids to test the effects of food quality (protein content) and reduced population density on the breeding performance of house mice (Mus musculus L.). The experiment was conducted in a rice field in New South Wales, Australia, in autumn (March-June) 1983, when there was an abundant supply of rice grain, so food energy was not a limiting factor for breeding. Protein was supplemented by ad libitum provision of oats and sunflower seeds. An increase in the protein content of the diet from 8% to 11% was associated with a significant increase in the proportion of females breeding. There was no breeding response to culling of females with head-body length ' 75 mm plus males < 82 mm, nor to interaction of culling x food-quality. The absence of a culling effect is discussed in relation to seasonal conditions and a previously postulated food-quality, spacing-behaviour hypothesis of mouse-plague formation.