Diagnosing the recent woylie (Bettongia penicillata) collapse in southwestern Australia

The woylie (Bettongia penicillata) has declined by about 80% since 2001. The rate of decline within affected populations has been up to 95% per annum. The largest and most important populations have been most severely affected. Examples include the last remaining indigenous populations of Dryandra (93% decline) and Upper Warren (95% decline), and the largest translocated populations of Batalling (97% decline) and Venus Bay Peninsula, South Australia (>90% decline). In January 2008, the Western Australian State Government re-listed the woylie as “fauna that is rare or is likely to become extinct” (Schedule 1, Wildlife Conservation Act 1950). Conservation status reviews in other jurisdictions are under way. The remaining small and translocated populations are inherently vulnerable - most have less than 200 individuals. The species collapse was unexpected. It followed a successful recovery of the species during the previous 25 years, due principally to the successes achieved by fox control in south-western Australian forests and woodlands and a strategic translocation program. The Woylie Conservation Research Project began in 2006 to identify the causes of the recent collapse. The study has focused on the populations within the Upper Warren region (east of Manjimup, Western Australia) - the largest wild woylie population, and where declines were still current. Highly collaborative and multidisciplinary, the progress of this research is reported with a focus on the possible role(s) of predation, food resources, and disease