The importance of species-specific survey designs: prey camera trap surveys significantly underestimate the detectability of endangered spotted-tailed quolls

Abstract

The spotted-tailed quoll (Dasyurus maculatus) is an endangered marsupial carnivore that is often surveyed using camera traps. Camera trap surveys targeting quolls typically use meat-based lures and specific camera setups tailored to increase the probability of quoll detection. However, where quolls occur, they can also be incidentally detected as non-target species in camera surveys targeting small to medium-sized herbivorous or omnivorous mammals (‘prey’ surveys). We investigated whether quoll detectability using traditional ‘prey’ camera surveys could sufficiently approximate quoll detectability using targeted ‘quoll’ surveys, potentially enabling quoll data from prey surveys to be used in lieu of undertaking additional quoll-specific surveys. We used 50 Reconyx HC600 cameras to quantify and compare quoll detectability between prey and quoll surveys at each of two different sites. The number of quoll detections, number of individual quolls detected and the probability of quoll detection at both sites were significantly higher in quoll surveys than in prey surveys. Our findings suggest that prey surveys substantially underestimate quoll detectability, resulting in incomplete datasets. We therefore caution against using quoll detection data from prey camera trap surveys for anything other than incidental presence observations, to avoid misleading survey and management outcomes.