Diet of the Hastings River mouse (Pseudomys oralis)

Abstract

The diet of the Hastings River mouse (Pseudomys oralis) has been assessed from 90 faecal samples collected from 42 animals in nine different locations in New South Wales. Repeated sampling of individuals over periods of 4-6 days gave consistent results confirming the reliability of the dietary estimation techniques used in this study. No differences were found between males and females when tested at two different sites. Eight dietary items were identified with the mean percentage occurrences for summer and winter, respectively, being: leaf, 45, 77; seed, 44, 12; insect, 7, 2; stem, <l , 7; flower, 2, <l ; pollen, 1, <1; fern sporangia, <1, 1; and fungi, <l , 1. A two-way ANOVA of geographical locality and season (summer v. winter) showed no locality effect, but a strongly significant season effect for leaf (P <0.0001), seed (P <0.0001) and insect (P < 0.007). A similar multivariate two-way ANOVA for overall diet also showed a significant season effect, but no locality effect. The summer co-dominance of leaf and seed shifted to almost complete dominance of the winter diet by leaf material. This differs from the trends in dietary composition of all other species of Pseudomys studied, which broaden their diet in winter to incorporate many different types of food. It is not clear whether this reflects an active choice by P. oralis to select for increased amounts of leaf, or a default selection caused by the lack of alternative dietary items, such as fungi, which are utilised in winter by the other species.