TheConservation western ringtail Science possum, W. Aust. Pseudocheirus 5 (2) : 235–257 occidentalis (2004) , and the quokka, Setonix brachyurus 235 The western ringtail possum, Pseudocheirus occidentalis, and the quokka, Setonix brachyurus, case studies: Western Shield review—February 2003 PAUL J. DE TORES 1, 2, MATTHEW W. HAYWARD 3, 4, 5 AND SUZANNE M. ROSIER 1 1Department of Conservation and Land Management, Wildlife Research Centre, PO Box 51 Wanneroo, Western Australia, 6946. 2 To whom correspondence should be addressed. [email protected] 3 Department of Conservation and Land Management, Dwellingup Research Centre, Dwellingup, Western Australia, 6946. 4 School of Biological, Earth and Environmental Science, University of New South Wales, Sydney, New South Wales, 2052 5 Current address: Addo Predator Re-introduction Project, Terrestrial Ecology Research Unit, Department of Zoology, University of Port Elizabeth, PO Box 1600, Port Elizabeth 6013, South Africa. ABSTRACT using fire as a tool to create the preferred structural habitat mosaic, is recommended. Case studies are presented for the western ringtail possum, Both case studies highlight the need to review data Pseudocheirus occidentalis, and the quokka, Setonix collection, collation, analyses and reporting processes to brachyurus. The ringtail case study summarises ensure data are collected in a manner to allow objective information from a recent review of the species’ analyses and scrutiny. Under this proposed scenario, any distribution and conservation status, collates information conservation gains can be quantified and documented. on ringtail populations within the areas covered by the Conversely, in circumstances where desired outcomes have Department of Conservation and Land Management’s not been met, the failure to meet set goals can be identified (CALM) fauna recovery program, Western Shield, and and mechanisms can be implemented to improve draws extensively on the recent findings from translocation conservation management. programs. Critical to the case study is the finding that (i) monitoring of the response to fox control programs is poor, or non-existent, at all known sites, with the INTRODUCTION exception of research specific translocation sites. This may reflect the difficulty in censusing and monitoring this species; and (ii) translocation success has not been Background and overview demonstrated at any translocation release site and the The western ringtail possum, Pseudocheirus occidentalis, primary translocation site, Leschenault Peninsula and the quokka, Setonix brachyurus, are within the suite Conservation Park, has suffered a significant population of mammal species considered at risk of predation by the decline. Hypotheses are proposed to explain this decline introduced red fox, Vulpes vulpes. Both species have shown and, in the absence of demonstrated translocation success, a contraction in geographic range and abundance since critical components for monitoring western ringtail the arrival of the fox in south-west Western Australia and possum translocations are recommended. Monitoring the fox has been implicated as a contributing factor to protocols are also recommended for other extant their decline (de Tores et al. 1998; de Tores et al. in review; populations within the species’ geographic range. de Tores, unpublished; Hayward et al. 2003). The quokka case study also summarises information The original Western Shield proposal (Burbidge et al. from a recent review of the species’ distribution and 1995) identified the western ringtail possum as a species conservation status and collates information on quokka likely to benefit from broad scale fox control and further populations within the areas covered by Western Shield. implied the quokka, and a suite of other small to medium The case study also draws extensively on the findings from sized mammals, would also benefit from fox control. With recent research from the northern jarrah forest. As for the commencement of Western Shield, many operational the ringtail case study, the quokka case study found baiting programs have been implemented and the native monitoring is non-existent or poor, or ad hoc at best, at fauna response to fox control has been monitored. all known sites, with the exception of research specific However, with the exception of site specific research sites within the northern jarrah forest. Consistent with programs, there has been no monitoring of western recently published research findings, intervention ringtail possum or quokka population response to fox management is recommended at these northern jarrah control. forest sites. An active adaptive management framework, 236 P.J. de Tores et al. Fox baiting has been in place at Leschenault Peninsula capture-mark-release-recapture (termed ‘mark-recapture’) Conservation Park as part of a translocation release methods for estimating population size are not program for the western ringtail possum since the early appropriate. Alternative techniques are labour intensive, 1990s and predates Western Shield. Similarly, other fox costly and require training of survey personnel to ensure baiting programs have been in place at sites where the data collection techniques are consistent and comparable western ringtail possum and the quokka are known to between locations. occur, although these programs were not specifically The quokka occurs in densely vegetated creeklines over designed or implemented to conserve either species. much of its range (Christensen et al. 1985; de Tores et al. The western ringtail possum site specific research has in review; Hayward, 2002; Hayward et al. 2004). been associated with translocation release programs of Conventional trapping in this habitat is physically difficult, rehabilitated orphaned and/or injured possums and labour intensive and has the potential to ‘open up’ the possums displaced as a result of vegetation clearing and vegetation and expose resident quokka populations to habitat modification or habitat loss at development sites. increased risk from fox predation (de Tores et al. in Monitoring of these populations has recently raised several review). Conventional trapping techniques can, and have issues of concern (de Tores and Rosier, unpublished-a; been used to, estimate quokka population abundance (see de Tores et al. unpublished-a; de Tores et al. unpublished- for example Hayward et al. 2003). However, with the b). Similarly, site specific research investigating the ecology exception of the study by Hayward et al. (2003), quokka of the quokka in the northern jarrah forest has identified trapping has usually been undertaken in an ad hoc manner issues of concern for conservation management of the and the data has provided information on presence only, quokka (see Hayward, 2002; Hayward et al. 2003; or at best has provided indices to abundance. These indices Hayward et al. 2004). are not necessarily comparable across sites. Alternative The case studies below summarise much of the recent techniques are currently being investigated, see for published and unpublished findings and propose specific example Alacs et al. (2003), where extraction of DNA recommendations relevant to Western Shield and from epithelial tissue sloughed with faecal pellets was used conservation management of both species. to confirm species presence. Similarly, Hayward et al. (unpublished-b) used faecal pellet counts to derive Terms of reference for the case studies estimates of quokka abundance. Importantly, this technique was validated by comparison with densities Specific terms of reference for the case studies were to: derived from mark-recapture techniques. i) outline the distribution, changes in status over time The sites listed in Table 1 indicate there is only one and probable causes of change for each species Western Shield monitoring site (quokkas at ii) identify the components of Western Shield being used D’Entrecasteaux, Nuyts Wilderness) where there has been in the management of each species (e.g. predator a response to fox control, albeit only inferred. This control, translocation) and the populations being response has been inferred by detection of faecal pellets managed at baited sites of unburnt vegetation immediately outside the boundary of a recent wildfire. Population size has not iii) identify all the people (and their roles) involved in the been quantified and there are no pre fire data on management of each species abundance. There are no other Western Shield monitoring iv) describe or tabulate the implementation of Western sites where the western ringtail possum or the quokka Shield actions with respect to each managed population has been shown to respond to fox control. Anecdotal and the process for modifying prescriptions accounts (often reported in the media) of increases in v) in consultation with key people from each involved abundance of the western ringtail possum and quokka as Region, assess the efficacy of the implementation of a result of Western Shield baiting are not supported by Western Shield actions and decision making procedures. quantified data. Similarly, records of occurrence have not been shown to equate with persistence of populations. The components of Western Shield, the The lack of a detectable response to fox control should people involved, populations monitored be interpreted cautiously. It should not be seen as and actions implemented in relation to the indicating an absence of response, but a reflection of the difficulty of deriving reliable estimates of abundance for western