Diet of two sympatric Australian subalpine rodents, mastacomys fuscus and rattus fuscipes

An analysis of the diet of two species of rodents, Mastacomys fuscus and Rattus fuscipes, living in subalpine heathlands at Smiggin Holes, New South Wales, was made by microscopic examination of faecal samples collected at three-weekly intervals from March 1978 to February 1979. The major proportion of the diet of M. fuscus, at all times of the year, was grass with a small proportion of dicotyledon leaf. In contrast, the diet of R. fuscipes varied considerably between seasons. In spring and summer, fungi were the principal food, and grasses and dicotyledons comprised less than one-third of the diet; in autumn, grasses became increasingly important, comprising the major part of the diet by midwinter. In both species, there were no changes in diet that could be closely related to the onset of winter (first snowfall) or to the end of winter (the thaw). The two species overlapped slightly in their diets in spring and summer and to a much larger extent in winter. Mastacomys fuscus is considered to be a specialist herbivore, R. fuscipes a generalist fungivore.