Severe, large-scale bushfire threatens metapopulation function of quokka (Setonix brachyurus) in south-western Australia

Abstract

Background The risk of large, severe bushfires is increasing in Australia, and little is known about their impact on threatened species. Aims This study aimed to investigated the abundance, occupancy and metapopulation structure of the quokka (Setonix brachyurus) for 5 years following a large, severe bushfire in Western Australia. Methods Data collected across spatiotemporally replicated transects were used to estimate probabilities of occupancy and abundance, and to evaluate the influence of covariates. Key results Quokka abundance was reduced to 16% of pre-fire levels, with distances up to 74 km separating subpopulations. Recolonising quokkas occupied habitat in parts of the landscape that had retained some vertical vegetation structure and contained a sedge-dominated understorey, and where damage by feral pigs was low. This coincided with topographic refugia that consisted of deep, mesic riparian systems or perched wetland systems. After 5 years, abundance had increased to 46% of pre-fire levels, with distances of 5–30 km separating subpopulations. Conclusion Quokka recovery rate is slower than expected, and the metapopulation remains vulnerable to further fragmentation arising from disturbances that affect habitat patch suitability and movement corridors. Implications Proactive protection of refugia and spatiotemporal habitat connectivity within and surrounding the fire scar is critical for metapopulation recovery.