Aim Occurrence records for cryptic species are typically limited or highly uncertain, leaving their distributions poorly resolved and hampering conservation. This can apply to well‐studied species, and increased survey effort and/or novel methods are required to improve distribution data. Here, we paired species distribution modelling (SDM) with decision tools to direct surveys for the critically endangered Leadbeater's possum (Gymnobelideus leadbeateri) outside its current restricted range. We also assessed survey areas for their suitability to host translocations. Location Victoria, Australia. Method We used both recent and historic records (now out of range and spatially uncertain) of Leadbeater's possum to build SDMs using MaxEnt. The SDMs informed an initial multi‐criteria decision analysis (MCDA) that enabled prioritization of 80 survey sites across seven forest patches (13–145 km outside the known range), which we surveyed using camera traps. Site and vegetation data were used in a post‐survey MCDA to rank their potential translocation suitability. Results The SDM predictions were consistent with the species’ ecology, identifying cold areas with high rainfall that had not recently burnt as suitable. The spatial uncertainty of records did not exert a strong influence on either model predictions or the ranking of patches for surveys. Camera trap surveys yielded records of 19 native species, with Leadbeater's possum detected in only one survey patch, 13 km outside of its previously known range. The post‐survey MCDA identified three forest patches as potentially suitable for conservation translocations, and these priorities were not sensitive to the decision criteria used. Main conclusions The approach outlined here prioritized survey effort over a large area, resulting in detection of Leadbeater's possum in one new patch. The potential translocation sites identified could present an important risk‐spreading measure for the species given the threat posed by bushfire. Combining SDMs and decision tools can help target surveys and guide subsequent conservation strategies.

Feral cats have been identified as a major threat to Australian wildlife; however, their impacts on the critically endangered Leadbeater’s possum (Gymobelideus leadbeateri) are unknown. Here, we describe camera trap observations of a feral cat hunting at nest boxes occupied by Leadbeater’s possum. Seven feral cats were subsequently captured within the surrounding area: two had Leadbeater’s possum remains in their stomachs. The prevalence of cat predation on this species, particularly at nest boxes, and how this can be mitigated warrants further investigation.

Artificial hollows are commonly used to mitigate the scarcity of den and nest sites that threatens fauna species globally, but there is a risk that these do not provide suitable microclimates for the populations they are intended to support. We monitored temperature, humidity and occupancy in artificial dens (nest boxes and chainsaw-carved cavities) provided for the critically endangered Leadbeater's possum (Gymnobelideus leadbeateri) in south-eastern Australian forests. Monitoring occurred over both winter and summer in five habitat types spanning a broad elevational gradient (110-1580 m asl). We then used a biophysical model to explore the physiological consequences of the den temperatures recorded, and the potential effectiveness of behavioural strategies in reducing thermoregulatory costs. Monitoring revealed that nest box temperatures tracked ambient over both seasons, ranging from À5.5°C to 48.5°C, while chainsaw hollows provided more stable internal conditions. However, we found that inferences regarding the thermal suitability of artificial dens were site-specific, and dependent upon habitat type, season and assumptions around behavioural strategies. During winter, behaviours such as the construction of large, insulative nests and huddling are likely critical in overcoming high energy costs associated with poorly insulated artificial dens. In contrast, during summer high thermoregulatory costs were predicted for the warmest (lowland) site and coincided with low nest box occupancy. Our study reinforces the importance of factoring in local climates, and behavioural and physiological strategies employed by target taxa, when implementing artificial den programs to support fauna populations.

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