Bringing back the endangered bridled nail-tailed wallaby at Taunton National Park (Scientific) through effective predator control

Abstract

Context. Feral cats (Felis catus), wild dogs/dingoes (Canis familiaris) and foxes (Vulpes vulpes) are predators of the endangered bridled nail-tailed wallaby (BNTW; Onychogalea frenata). Predator-proof fencing is advocated as a solution to ensure their conservation in the wild.Aims. The aims of this study were to determine whether predator control translated into a reduction in their activity, find evidence of cats preying on BNTWs and understand factors that influence changes in the BNTW population size living in an unfenced reserve, particularly focusing on the influence of cat and dog control and rainfall.Methods. An activity index, calculated using spoor on sand pads and images on remote cameras, was undertaken to monitor predator activity. The stomach contents of cats caught were examined to determine how commonly BNTWs feature as a prey item. The size of the BNTW population and annual survival of individuals was assessed through annual capture-mark-recapture (CMR) surveys and vehicle spotlight counts. Rainfall was measured at the study site and using data from the Bureau of Meteorology.Key results. The core BNTW population estimated by CMR data increased by 214% over 4 years (2013)(2014)(2015)(2016)(2017), to 400 individuals in 2017, whereas spotlight data indicated that the population had increased by 262% over 8 years (2012)(2013)(2014)(2015)(2016)(2017)(2018)(2019)(2020), to 1265 individuals in 2020. The percentage of small (#3.5 kg) BNTWs caught increased substantially over the study period. There was no detectable difference in cat or dog activity following control and no correlation was found among predator activity, rainfall and BNTW survival. The remains of BNTWs were found in 20% of cats removed from the core BNTW area.Conclusions. The study confirmed that cats frequently ate BNTWs, and a combination of control methods is required to manage the threat, but there was no statistical support for a relationship between predator activity and BNTW survival.Implications. The study found that native species conservation in fox-free environments is possible without the need for predator-proof fences and the ongoing maintenance costs.