Community structure of dasyurid marsupials in the arid Pilbara is consistent with a top-down system, their distribution and abundance depend on that of larger members of the guild

Abstract

The semi-arid Pilbara region of Western Australia has an exceptionally large number of sympatric carnivorous marsupials (dasyurids). The multi-scale patchwork of sandplain grassland, riparian and rock outcrop habitats overlain with fine-scale variation in fire age may provide opportunities for exceptional niche differentiation. The goal of this study was to determine how dasyurids in the Pilbara partition these habitats in space and time. We focused on four species detectable on camera traps: northern quolls (largest), mulgaras, kalutas, and stripe-faced dunnarts (smallest). We found fine-scale partitioning in spatial and temporal patterns among sympatric species, and unusually, fire age specialisation in the smallest species, dunnarts, which were associated with recently burnt areas that had low prey availability. Kalutas were active throughout the 24-h period, with seasonal differences that support the hypothesis of energy preservation. Opposing habitat associations of kalutas and dunnarts are consistent with top-down pressures. We suggest that, in habitats where quolls and mulgaras are absent, kalutas may have experienced mesopredator release.