Stuck in the mud: Persistent failure of ‘the science’ to provide reliable information on the ecological roles of Australian dingoes

Abstract

Apex predators are believed to play important roles in maintaining the structure and function of ecological systems, but actual evidence for mesopredator releases and trophic cascades in terrestrial systems is mixed and equivocal, largely due to the systemic and continued use of weak-inference or correlative study designs to investigate these hypothesised causal processes. Here we critically review the experimental designs of empirical studies examining relationships between dingoes and mesopredators in Australian ecosystems. We found that 83 % (30 out of 36) of recent study designs lacked one or more of the essential experimental design elements needed to assess causal relationships (such as experimental treatments and controls, treatment replication, and/or treatment randomisation), demonstrating that the inferential strength or reliability of ‘the science’ on this subject remains weak and equivocal. Only five studies published in the last decade (N = 36), and eight in total since 1993 (or 11 %, N = 76), were capable of assessing dingoes' potential causal roles in mesopredator release; and all eight studies consistently demonstrated that dingoes do not supress mesopredators or initiate trophic cascades through mesopredator release effects at a population level, independent of ecological context. Thus, there is a demonstrable absence of evidence and evidence of absence for dingo suppression of mesopredators in Australia. We encourage large carnivore conservation managers and policymakers to base their decisions on the strongest available science. In this way, researchers and managers will have the best chance of conserving these important and valuable species into the future.