Habitat Associations and Niche Partitioning in an Island Dung Beetle Community

The composition and habitat associatons of the dung beetle community on Flinders Island (in Bass Strait between Tasmania and the Australian mainland) were assessed to provide baseline data prior to the deliberate introduction of exotic dung beetles for control of dung and dung-breeding flies. The distribution of beetles in relation to vegetative cover and dung type was examined in an experiment, in which pitfall traps were baited with a range of dung types in a variety of contrasting habitats, and by qualitative survey. The beetle community consisted of nine indigenous species (six Onthophagus and one Aphodius species (Scarabaeidae), two Saprinus species (Histeridae)) and two introduced species (Cercyon (Hydrophilidae) and Aphodius). Seven species were diurnal and four were noctural/crepuscular. Five species were strongly associated with woodland and the remainder occurred primarily in open pasture. All species were substantially more abundant in traps baited with human dung than in those baited with herbivore dung. Some species were caught at human dung almost exclusively. There were no obvious effects of herbivore dung type (cow, horse, marsupial, sheep) on the numbers caught in traps. Beetles were more numerous in cattle paddocks than in sheep paddocks. Four indigenous species which are common in cattle dung in open pasture (Onthophagus australis Guerin, Onthophagus granulatus Boheman, Onthophagus posticus Erichson and Aphodius tasmaniae Hope) have niche characteristics that make them potential competitors with exotic species to be introduced from the mainland.