Ecology of the Northern Bettong, Bettongia tropica, a Tropical Mycophagist

Abstract

The diet and seasonal ecology of the northern bettong, Bettongia tropica, was studied at three sites along a moisture gradient from closed Allocasuarina-Eucalyptus forest to dry open woodland in north-eastern Queensland. At each site, fungi (sporocarps of hypogeous ectomycorrhizal species) were the major food, and most of the remainder of the diet consisted of grass leaf and stem, roots and tubers, and lilies. Forbs and invertebrates were also eaten, but in small quantities. Fungus consumption was greatest at the wettest forest type and least at the driest site. Seasonal variation was insignificant except at the driest site, where fungus consumption peaked in the late wet season and dropped during the dry season; this seasonal fall in fungus consumption was associated with an increase in consumption of grass and roots and tubers. There was little seasonal variation in body condition, except at the driest site, where the dry-season decline in the proportional representation of fungus in the diet was associated with a decline in body condition. Breeding was continuous and aseasonal. B. tropica is found only in a narrow zone of sclerophyll forest along the western edge of wet tropical rainforest in north-eastern Queensland. We suggest that this species (like bettongs and potoroos in southern Australia) depends on hypogeous fungi, and that expansion of its geographical range into drier forest types is prevented by shortages of fungus during the dry season.