The Hidden Diet: Determining the Distribution of the Threatened Julia Creek Dunnart (Sminthopsis douglasi) using Eastern Barn Owl (Tyto javanica delicatula) Pellets

Abstract:

Approximately 30% of the world's biodiversity has been threatened or driven to extinction since the 1500s, with Australia losing 10% of its endemic terrestrial mammal species in the last 200 years. The Julia Creek dunnart (Sminthopsis douglasi) is a threatened small mammal endemic to Queensland (Australia) that requires monitoring and protection. However, there is insufficient ecological data to determine its distribution adequately, and the species has only been sporadically caught in live trapping surveys. In the present study, eastern barn owl (Tyto javanica delicatula) pellet analysis was used to assess nine locations for the presence of the Julia Creek dunnart as a prey species. Owl pellet deposit sites were chosen to encompass areas of high, medium and low likelihood of Julia Creek dunnart occurrence based on Australian Government habitat models for the species with the goal of better understanding the species' distribution. Julia Creek dunnarts were present at four locations, including all high likelihood locations, half of the medium likelihood locations and no low likelihood locations. This result supported the accuracy of the Australian Government habitat models. Results also demonstrated the importance of the long-haired rate (Rattus villosissimus) in eastern barn owl diet during plague years. The research will assist with prioritising sites for protection and monitoring of the Julia Creek dunnart. It also adds support to the utility of owl pellet analysis alongside or independent of traditional surveying techniques, such as live trapping, when targeting cryptic small mammal species.