The application of catch–effort models to estimate the efficacy of aerial shooting operations on sambar deer (Cervus unicolor)

Context Aerial shooting from a helicopter targeting introduced sambar deer (Cervus unicolor) is key activity being undertaken on public land in the North East and Gippsland regions of Victoria. However, there currently little published information efficacy aerial for reducing populations Australia. Aims The aims this study were to analyse operational data collected during an program eastern Victoria, assess at density inform management decisions required intensity achieve target densities. Methods Operational (locations all shot animals as well search effort) analysed 10 sites using Bayesian generalised catch–effort model, which allowed population changes between five periods intensive control. model estimates initial residual abundance each site be made data, used estimate shooting. Estimates detection rate deer, vary with removal occasion site, then amount effort reduce densities by various proportional amounts. Key results resulted reductions 50–70% four where intensities per unit area highest. remaining suggest that have either remained static or increased over Recruitment control periods, was strongly influenced elevation season, largely responsible eroding achieved Conclusions Catch–effort models applied programs can without need additional monitoring. Our analysis suggests sufficiently high intensities, around 1.4 km km2 habitat occasions, would least 50% reduction