Justification for continued conservation efforts following the delisting of a threatened species: a case study of the woylie, Bettongia penicillata ogilbyi (Marsupialia:Potoroidae)

Abstract

Context. There are few cases where a species has been removed from a list of threatened species as a result of conservation efforts. One such example is the woylie (also known as the brush-tailed bettong), Bettongia penicillata ogilbyi, which was removed from state (Western Australian), national (Australian) and international lists in 1996, following the successful implementation of the species’ recovery plan. Since downgrading of its conservation status, the woylie has been considered conservation dependent. Conservation efforts continued in the form of toxic baiting to control the species’ principal predator, monitoring to identify trends in distribution and abundance, and translocation to help restore ecosystem function and further secure the conservation status of the species. Recent observations of a decline in abundance of the species have prompted a review of its conservation status. Aims. To assess the conservation status of the woylie in 2006 against IUCN criteria and to investigate the value of continued conservation efforts following the delisting of the species. Methods. Monitoring data were collated and parameters required to assess the conservation status of the woylie against IUCN criteria were investigated. The various processes associated with conserving the species, such as translocation and monitoring, were also assessed. Key results. The species underwent a rapid decline between 2001 and 2006, reducing the population by ~75% to an estimated 10 000 individuals. The decline has not been consistent across occurrences and of particular concern are the declines observed at Perup/Lake Muir, Dryandra and Batalling, which were previously considered amongst the largest and most stable occurrences. In 2006, the species qualified for listing as Endangered using IUCN criteria. The resources allocated to translocation and monitoring the delisted woylie have ultimately resulted in managers being in a much better position to understand and act when an unforeseeable population decline occurred. Conclusion. Conservation efforts and population monitoring of delisted species must continue at a level where changes in distribution or abundance, which are significant enough to support relisting, can be detected. Implications. Threatened species lists should not be the primary consideration in allocation of resources to conservation efforts.