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Testing the efficiency of thermal imagers for detecting arboreal marsupials in temperate forests

Nicholas Tan , José Lahoz-Monfort, Brendan Wintle

Abstract

Context: Wildlife monitoring must be cost-efficient due to constrained conservation budgets. Part of efficient monitoring is the selection of appropriate and effective methods for monitoring species Aims: In this paper, we evaluated the effectiveness of two methods (spotlighting and thermal imaging) for detecting four species of arboreal marsupial in the Strathbogie region of northeastern Victoria, Australia. Methods: We conducted 108 visits to 15 survey locations across the study area over the period Nov 2017-Jun 2018. Each survey was conducted as a 250m transect over 20-30 minutes. Occupancy modelling was used to evaluate the influence of observation method choice on detectability while accounting for other covariates. We calculated the expected minimum number of visits required to achieve a low (0.1) probability of failing to detect each of the four target species. Key results: We found that spotlighting was best used for detecting greater gliders and ringtail possums, while thermal imagers were best for detecting mountain brushtail possums and koalas. Detectability estimates indicated that a minimum of 3 spotlighting or 4 thermal surveys should be planned. Physiology is a likely factor in the differing number of surveys for each method-species combination. Conclusions: The choice of method for detecting arboreal marsupials is dependent on several factors including the physiology of the target species Covariates may play a part in detectability of some species, although the greater glider remains highly detectable regardless of method. Implications: Behavioural and physiological differences between arboreal species can impact the effectiveness of survey method. Foraging activity and response to stimuli like spotlights affect detectability and should be considered when plotting survey methodology.

WR25054  Accepted 05 September 2025

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