Impact of wildlife culling on the physiological stress and space use of a social herbivore

Wildlife culling is a widely used but often contentious management tool for controlling overabundant species. While previous research suggests that behavioural responses of eastern grey kangaroos (Macropus giganteus) to culling are relatively minor, physiological measures can offer additional insight into how animals perceive such events. In this study, we assessed changes in faecal glucocorticoid metabolite (FGM) concentrations to evaluate the physiological response of kangaroos to a conservation cull in the Australian Capital Territory. We collected faecal samples immediately before (n = 255) and after (n = 171) the cull and analysed FGM levels alongside patterns of space use inferred from GPS-located faeces. Post-cull FGM concentrations were 29% lower than pre-cull levels, suggesting a subdued physiological response inconsistent with what might be expected following a major predation-like event. Additionally, kangaroos were found to graze further from refuge sites after the cull, further indicating reduced stress or increased perceived safety. Our findings align with previous behavioural data and suggest that the culling operation had minimal negative impact on the remaining individuals. This study highlights the value of incorporating physiological metrics into wildlife assessments and demonstrates the importance of multi-faceted approaches in evaluating the outcomes of wildlife management interventions.