Spatial niche separation of an invasive and a native mesopredator

Abstract

Re-introduced native animals face major challenges to re-establish themselves in their previous range of distribution when invasive alien predators are present. We study the interactions between a native and an invasive mesopredator across an ecological gradient in the Ikara-Flinders Ranges National Park in South Australia. We placed VHF/ GPS-collars on feral cats (Felis catus) and re-introduced western quolls (Dasyurus geoffroyi) and analysed their movement patterns, both utilisation distributions and behavioural states, and habitat selection. Despite being able to move anywhere in this open landscape, there is a clear interspecific difference between the two species in their use and preference for landscape elements. Cats prefer grassland and occupy flat areas where rabbit densities are high. Quolls prefer forests and avoid areas of high rabbit and therefore areas of high cat density. The almost complete spatial separation of cats and quolls may reflect different habitat requirements, but the historically broad distribution of quolls suggests that cats may limit quolls continuously to a restricted niche in the Flinders Ranges. This raises the possibility of management interventions that could support a further expansion of quoll occupancy.