Ecology of the rare but irruptive Pilliga mouse, Pseudomys pilligaensis. III. Dietary ecology

The diet of the Pilliga mouse, Pseudomys pilligaensis, was analysed from 430 faecal samples collected from ~340 individuals across different seasons over a period of five years that included a wild fire and subsequent irruption and sharp decline of the population. The primary food items in all seasons were seeds and fruits from diverse plant species, but the mice also consumed a wide range of other foods, including leaves, invertebrates, fungi and mosses. Invertebrates, the second most abundant type of food item, were eaten in all seasons but, with fungi, increased in winter and spring when consumption of seeds and fruits declined. Mice consumed significantly more fungi and mosses before the wild fire than after it. Diets differed between sites rather little in the proportions of food categories, but greatly in the relative proportions of particular seed types in the seed+fruit category. The population irruption could have been triggered by a high reproductive rate that coincided with higher consumption by females of protein-rich foods such as invertebrates and fungi. Population density collapsed at sites as soil stores of utilisable seeds became depleted, mice surviving where their diet could remain diverse.