Recovering endangered populations in fragmented landscapes: the squirrel gliderPetaurus norfolcensis on the south-west slopes of New South Wales

Abstract

The squirrel glider Petaurus norfolcensis is listed as a vulnerable species across New South Wales. The population in the Wagga Wagga Local Government Area was considered to be at a higher level of threat (i.e. in immediate danger of extinction) and was classified as an endangered population in 2000. The determination to list this population was made largely on the basis of limited point locality records of the species and an assessment of the extent of habitat clearing. This decision to designate the population as endangered was valid at the time and we do not dispute the fact that squirrel gliders within the Wagga LGA are at serious risk of extinction. However, recent surveys have revealed that the species is more widespread across the South West Slopes Bioregion of NSW than initially recognised. Despite this situation, the future conservation status of the squirrel glider is still uncertain due to extensive historic clearing and fragmentation of habitat as well as ongoing incremental loss and degradation of key resources. The new information about the distribution of squirrel gliders raises questions about the most effective approach, including the spatial scale, at which to manage and recover widespread but vulnerable species. We recommend that a landscape-scale approach that incorporates metapopulation theory be adopted to define and manage disjunct populations. There are likely to be numerous disjunct populations across the south-west slopes that are as equally endangered as the population(s) in the Wagga LGA. Therefore, a necessary first step in recovering squirrel gliders is to develop habitat models that describe and predict the occurrence of the species and delineate population boundaries. Other critical steps include: (i) reducing threats; (ii) maintaining a perpetual supply of key resources; and (iii) undertaking strategically located revegetation programs to increase total habitat and link isolated populations. Finally, the need to test and potentially revise the feedback process under the Threatened Species Conservation Act 1995 is also recommended.