Ten years of camera trapping for a cryptic and threatened arboreal mammal – a review of applications and limitations

Abstract

For many cryptic mammal species, limited distributional data restrict the scope or effectiveness of conservation actions, particularly in relation to habitat protection and/or management. The critically endangered Leadbeater’s possum illustrates this, with wet forests throughout its range impacted by logging and bushfire. The possum’s habitat has been subject to major disturbance and degradation over recent decades; however, the cryptic behaviour of the species has meant population trajectories have been difficult to monitor. Since 2012, surveys for the possum have been greatly expanded, predominantly based around camera trapping. This paper examines outcomes following a decade of targeted camera trapping for this high-profile threatened species. There have been 1143 camera trapping detections of Leadbeater’s possum since 2012, representing 57% of all detections over this period. For comparison, there were just 274 detections of the species over a comparable period during the preceding decade using all other survey techniques. The substantial increase in records reflects greater survey effort, but also the effectiveness of baited camera traps at detecting this cryptic mammal. As a consequence, we have greatly improved understanding of the species’ distribution within its core range following major bushfire in 2009. These detection data have informed some aspects of forest management, including the establishment of small logging exclusion areas. Other applications of camera traps have included directing them at dens, providing a non-invasive means of monitoring translocated individuals and reproductive success. Several important caveats regarding camera trapping surveys are discussed, particularly that detection/non-detection data may be insensitive at detecting population declines for communally-denning species such as Leadbeater’s possum, where abundance may change more readily than occupancy. A risk accompanying the proliferation of camera trapping is over-reliance on rapid, one-off camera surveys that fail to provide the in-depth insights on demography and population dynamics required to inform effective management of threatened species. This case study highlights the importance of robust survey and monitoring data to inform species conservation planning and management. The results also demonstrate that camera trapping can be as effective and efficient in determining occupancy for some arboreal mammals as it is for terrestrial species, where it is more commonly applied.