Optimising camera trap surveys for the rocky landform fauna of the Mount Isa Inlier, Queensland: insights from a multi-scale analysis of the Carpentarian Pseudantechinus (Pseudantechinus mimulus)

Jarrad Barnes

doi:10.25907/00912

Rocky landforms are complex and enduring habitats that provide both spatial refuge from short-term local threats (e.g., predation, fire) and temporal refugia from persistent impacts that act on long timescales (e.g., climate change). Despite this critical function, few rocky landforms throughout Australia have received detailed attention. The Mount Isa Inlier is just one of many regions across Australia that are expected to face increasingly severe impacts from a multitude of disturbance mechanisms in coming decades, likely intensified by climate change. Rocky landforms in the area will therefore be of increasing importance to the fauna of the region, yet they remain relatively underrepresented in the scientific literature. I conducted baited camera trap surveys across 631 camera trap stations over a study area of 269,736 km2. Surveys were conducted between May 2018 and August 2021, with a total survey effort of 50,732 camera days. Surveys were partitioned into (1) an initial intensive 13-month study investigating the presence of fauna on rocky landforms in the Mount Isa Inlier, Queensland, and (2) an extensive distributional survey targeting one rocky landform species, the Carpentarian Pseudantechinus (Pseudantechinus mimulus) throughout northern Queensland and portions of the Northern Territory. Camera traps captured 1,623,548 photos, comprising 55,152 independent detections of 92 taxa identified to at least genus level. To my knowledge, this is the largest camera trap survey effort undertaken in my study area. The initial study recorded 31,673 independent detections over 21,965 camera days of 15 specialist saxicolous fauna occupying rocky landforms of the Mount Isa Inlier bioregion. I implemented a multi-season community occupancy model based on a condensed dataset of 10,966 camera days to assess how this rocky landform specialist community utilised its habitat over a year and according to environmental characteristics. I found significant variations in patterns of use of the landscape over time and space by the community and by individual species. The initial study highlighted that the Carpentarian Pseudantechinus (Pseudantechinus mimulus) presented an ideal opportunity to simultaneously improve understanding of an understudied dasyurid marsupial and develop a survey framework for a range of rocky landform specialists. From the initial survey, detection probability was calculated for P. mimulus within a single-species, multi-season occupancy framework and applied to determine the optimum timing and duration of surveys for P. mimulus. Using these parameters as guidelines, I conducted an extended camera trap survey totalling 28,767 camera days, with the aims to (1) refine the contemporary distribution of P. mimulus, (2) determine landscape and floristic variables that predict P. mimulus presence, and (3) assess the current conservation status of P. mimulus. The distributional study produced a comprehensive species distribution model, and provided new evidence for broad factors that help predict the presence of P. mimulus, highlighting potential locations and environmental parameters for future surveys targeting the species. Additionally, an increase in the species’ known range in QLD of ~60 km north, ~15 km south and ~20km west was determined, and highlighted the possibility of the existence of two disjunct populations. Based on the protocol developed for P. mimulus, this thesis provides detailed guidelines for conducting camera trap surveys for P. mimulus and 11 other species for which sufficient data were available and highlights broad site attributes of candidate areas for management and conservation initiatives within the Mount Isa Inlier. The protocols and guidelines presented in this thesis serve as a framework for conducting camera trap surveys targeting other rocky landform communities, many of which are likely to become increasingly reliant upon rocky landforms for refuge and refugia in coming decades under projected land management and climate change scenarios.

Optimising camera trap surveys for the rocky landform fauna of the Mount Isa Inlier, Queensland: insights from a multi-scale analysis of the Carpentarian Pseudantechinus (Pseudantechinus mimulus)

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