Stress-Testing Monitoring Design to Lock in Conservation Success

Effective monitoring of threatened species is key to identifying trends in populations and informing conservation management decisions. However, clearly defined monitoring questions that are informed by local circumstances and species traits are commonly neglected. We propose a decision framework as a guide to prioritise what data to collect and methods to use for population monitoring. We applied our decision framework to trial monitoring of Gang-gang Cockatoos (Callocephalon fimbriatum), a threatened, iconic species in Southeast Australia. To meet our program objectives, we trailed distance sampling surveys to estimate population abundance across the urban landscape in the Australian Capital Territory. Despite consistently high reporting rates in the study area, detection rates were too low to estimate the abundance of Gang-gang Cockatoos. As part of assessing the appropriateness of distance sampling as an approach, we simulated surveys under a hypothetically inflated survey effort and population size. Simulations show that even if our field survey effort was doubled or if the population size of Gang-gang Cockatoos was improbably high, detections would remain too low for distance sampling to be a practical approach. We then revisit our decision framework to make new recommendations for future monitoring of Gang-gang Cockatoos and demonstrate the importance of a clear monitoring framework when evaluating how best to achieve conservation goals in the context of methodological uncertainty. The first steps of designing and implementing a monitoring program are crucial—our decision framework offers practitioners a clear, reasoned approach to deciding which methods are needed to address their conservation objectives, along with contingencies for when plans go awry.