Conserving the Endangered Woylie (Bettongia Penicillata Ogilbyi): Establishing a Semi-Arid Population Within a Fenced Safe Haven

Home , Woylie

RESEARCH doi: 10.1111/emr.12402 REPORT Conserving the endangered woylie (Bettongia penicillata ogilbyi): Establishing a semi-arid population within a fenced safe haven

By Michael Smith, Georgia Volck, Nicola Palmer, Chantelle Jackson, Carly Moir, Raquel Parker, Bryony Palmer and Adele Thomasz

Michael Smith, Georgia Volck, Nicola Palmer, Summary Measuring and monitoring population size and growth are critical to assess- Chantelle Jackson, Carly Moir, and Raquel ing the progress and ultimately the success (or failure) of a reintroduction. The Woylie (Bet- Parker a Regional Ecologist, Senior Field tongia penicillata ogilbyi) is one of Australia’s threatened critical weight range mammals. To Ecologist, Senior Field Ecologist, Senior Field increase the species’ area of occupancy, extent of occurrence, number of sub-populations and global population size, in addition to creating a source population for future reintroduc- Ecologist, Field Ecologist, and Field Ecologist, tions, a new population has been re-established into a safe haven located within the spe- respectively, with the Australian Wildlife cies’ former range – Mt Gibson Wildlife Sanctuary. In this paper, we document the first Conservancy (PO Box 8070 Subiaco East, Perth, 3 years of the reintroduction programme, over which time 162 individuals were translocated WA 6008, Australia; Email: Michael.Smith to Mt Gibson. Specifically, we (i) provide information on survivorship, (ii) estimate changes @australianwildlife.org). Bryony Palmer and in critical population metrics (density, population size and distribution) and (iii) look for any major habitat preferences. Survivorship of collared animals was complete (i.e. zero mortal- Adele Thomasz are both former Field Ecologists ity). The most recent population estimate was in the order of 750 individuals, reflecting with the Australian Wildlife Conservancy. strong growth in population size and density. The woylie has occupied the majority of the Bryony is now a PhD candidate at the safe haven and is well represented in all major vegetation communities. The translocation University of Western Australia (Ecosystem is on track to meeting the key success criteria: a self-sustaining population of woylies with Restoration & Intervention Ecology Research a minimum of 300 individuals. Group, School of Biological Sciences, The Key words: population size, reintroduction, survival, Woylie. University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, Australia, 6009). Adele Thomasz, Formerly Field Ecologist with the Australian Wildlife Conservancy (PO Box 8070 Subiaco East, WA 6008, Austarlia; Email: [email protected]) This project arose from a need to assess the success of a reintroduction programme for the Woylie.

fecundity; Royle et al. 2013) are considered fundamental metrics in threatened species Implications for management (Williams 2002). Addi- Introduction et al. managers tionally, by monitoring population abun- o assess the success of a translocation dance, managers should be able to programme, it is particularly important correlate change with monitored pro- This work provides information on T to monitor initial survival, population cesses. Managers then have a pathway to the establishment of a new growth and the dispersal of individuals, enact management, whether it be to population of Woylies in a semi- with a view to ultimately understanding reduce population size of key predators arid setting, with an additional the capacity of a management area to sup- or competitors, increase emigration rates, emphasis on describing a port a particular population size (i.e. carry- fence off areas to allow vegetation recov- monitoring approach (and ing capacity) and its ‘normal’ oscillations ery, genetically supplement the population subsequent analysis) that can be (i.e. Robert et al. 2015). For these and and so on. It is, therefore, also very impor- applied to species that are other reasons, population density and tant to identify key risk factors for monitor- commonly monitored via cage abundance (and underlying processes such ing (Burgman 2005; Metcalf & Wallace trapping. as immigration, emigration, survival and 2013; Smith et al. 2015) and to, over time,

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Ecological Society of Australia RESEARCH REPORT develop targets and evidence to inform a populations and three translocated popu- Release site theory of management, such as a carrying lations (Yeatman & Groom 2012; Woi- Mt Gibson Wildlife Sanctuary is managed capacity and limits of acceptable change narski et al. 2014). by the not-for-profit organisation, the Aus- (Rogers et al. 2013; Gell et al. 2016). In this study, we document the estab- tralian Wildlife Conservancy (AWC). The The Brush-tailed Bettong (Bettongia lishment and dispersal of a new popula- property is approximately 132,500 ha penicillata) is one of Australia’s threatened tion of woylies released into a 7,838 ha and is located about 350 km north-east critical weight range (CWR) mammals safe haven (Fig. 1) and report on initial of Perth (Fig. 1). Mt Gibson is in a transi- (Burbidge & McKenzie 1989; but see Cardi- survival, changes in population density tion zone between the wetter south-west llo & Bromham 2001). Once distributed and abundance, and habitat utilisation and the more arid Eremean region. It fea- across much of the continent, populations over the first 3 years post-reintroduction. tures a mix of Acacia shrublands, various of the Brush-tailed Bettong collapsed fol- In addition to providing a new source pop- Eucalyptus woodlands and Callitris-domi- lowing the introduction of the Red Fox ulation for future translocations, the pri- nated vegetation communities. A 1.8 m (Vulpes Vulpes) and Cat (Felis catus; Yeat- mary aim of this reintroduction was, as high fence surrounds 7,832 ha and pro- man & Groom 2012). By the 1970s, only a per IUCN guidelines (IUCN 2012), to vides a barrier to cats and foxes and other few populations of the Western sub- increase the overall area of occupancy, similarly sized or larger terrestrial verte- species, the Woylie (Bettongia penicillata extent of occurrence, number of sub-pop- brates. Control efforts ensured that the ogilbyi) persisted in south-western Wes- ulations and global population size of woy- safe haven was free of cats, foxes and tern Australia. With a concerted manage- lies (Ruykys & Kanowski 2015). By goats (Capra aegagrus hircus), after ment effort, primarily broad-scale control developing a robust monitoring pro- which a reintroduction programme for of the fox and translocations, the species gramme, ongoing management can pro- ten regionally extinct mammal species was downgraded to ‘low risk’ (conserva- ceed in an adaptive manner with a view was instigated (Kanowski et al., 2018). tion dependent) in 1996 (Start et al. to assessing the success of the transloca- Before the second survey (October– 1998). However, between 1999 and 2006 tion and developing an understanding of November 2017), 71 Banded Hare-walla- the woylie declined again by c. 90% carrying capacity and its management. bies (Lagostrophus fasciatus), a macro- (Wayne et al., 2015) and in 2008 was re- pod herbivore, had been translocated to listed as ‘fauna that was rare, or likely to Mt Gibson. Other than Banded Hare-walla- become extinct’ under the Western Aus- Materials and Methods bies, translocations for Numbats (Myrme- tralian Wildlife Conservation Act 1950, Translocations cobius fasciatus), Greater Bilbies and as critically endangered in the IUCN (Macrotis lagotis), Red-tailed Phascogales Red List (Woinarski & Burbidge 2016). In Woylies were reintroduced to Mt Gibson (Phascogale calura), Greater Stick-nest 2009, it was listed as endangered under from August 2015, with translocations Rats (Leporillus conditor), Shark Bay the Environment Protection and Biodi- being completed by July 2019. Animals bandicoots (Perameles bougainville) and versity Conservation Act 1999 (Groom were translocated from the Karakamia Shark Bay Mice (Pseudomys fieldi) had 2010). Clearly, developing a robust moni- Wildlife Sanctuary, Perup Sanctuary, and begun. However, most of these species toring programme for every woylie popula- Whiteman Park (Yeatman & Groom are not herbivores and all were considered tion is particularly important if managers 2012); these source locations were to be in low enough numbers to not have are to identify and respond to unwanted selected to maximise the genetic diversity had sufficient time to have made signifi- changes in population size in a timely man- of the reintroduced population (Pacioni cant impact upon food availability or veg- ner. et al. 2013). A total of 162 woylies (90 etation structure. Predation by introduced foxes and cats males:72 females) from the three sources is considered an important factor in the were translocated to Mt Gibson and Survival declines of CWR mammals, including the released at a series of pre-determined woylie (Woinarski et al. 2014). One release sites (Fig. 1). Fifty individuals were To assess their survival, 40 individuals (14 approach to manage the impacts of foxes released into Mt Gibson (from Karakamia males:26 females) translocated between and cats is the creation of fenced or island Wildlife Sanctuary) in 2015. A further nine September 2015 and September 2016 ‘safe havens’ from which introduced individuals were translocated from Kara- had radio-tracking collars (Sirtrack V5C predators (and other unwanted species) kamia and 32 from Perup Sanctuary in 163E 130–260 mm or ZV6C 163D 130– are removed (Legge et al. 2018) to which 2016. Fifteen individuals were translo- 260 mm) attached at release. Collars were predator-vulnerable species can be rein- cated from Whiteman Park to Mt Gibson all below 5% of the animal’s body weight. troduced. Reintroductions of the woylie in 2017 and a further 56 from Perup Sanc- Animals were tracked daily for the first to such areas have made a major contribu- tuary to Mt Gibson in 2018. Thus, only 15 2 weeks post-release, and twice weekly tion to securing the species, with ten pop- individuals were translocated to Mt Gib- for the following 2–4 weeks and then ulations established within island or son after the 2017 survey, but before the weekly until either the collars fell off mainland safe havens. Outside of safe 2018 survey from which data are reported or reached approximately 25% of their havens, there are only two ‘natural’ herein. expected battery life, at which point

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processed. Animals were scanned and microchipped when necessary and had their sex, age, reproductive status, weight, pes length and general condition mea- sured. Animals were released, by approximately 08:00 AWST. When required, a microchip was inserted (following Depart- ment of Biodiversity, Conservation, & Attractions 2017). A combination of Avid, Biomark and Trovan microchips had been used at the source sites but, on recapture at Mt Gibson, only Trovan 9-mm microchips were used. The technique of having multiple traps per site and checking traps twice per night in 2017, or having four traps per site in 2018 (but single-trap clearing), ensured that open traps generally remained available to woylies for the entire trap night and thus reduced the effects of the species’ trap happiness. Given the different Location of the Mt Gibson Wildlife Sanctuary (solid black line) and the fenced safe Figure 1. sampling approach employed, each haven (dashed line). year’s trapping results were analysed sep- arately. The SECR approach is designed to esti- animals were caught and their collars two (2017) and four (2018) wire-mesh mate density and alleviate the issues with removed. Tracking involved confirming cage traps (20 cm 9 20 cm 9 56 cm) the definition of effective trapping area the survivorship of each individual (as were placed at 40 sites in the northern that are associated with more standard determined by pulse frequency, with a third of the safe haven for three trap mark–recapture approaches (Efford & doubling of the same if no movement nights (Fig. S1). The cages were then Fewster 2013; Royle et al. 2013). had been detected by the collar for 10 h). moved to 40 sites in the centre of the safe Although these are not major issues here haven for the subsequent three trap nights because the study area is defined by the and, finally, to the southern end of the safe safe haven fence, the approach allowed Estimating density and population size haven for the last three trap nights us to readily model spatial variation in den- Woylies are easily trappable, so cage trap- (Fig. S1). Sites were located by first creat- sity, an explicit goal of the monitoring. In ping is an inexpensive, well-established ing a 50 m buffer around the vehicle particular, SECR models the spatial distri- and potentially effective approach to mea- tracks within the safe haven and then ran- bution of latent individual activity centres sure population size. However, the spe- domly assigning 120 points within the buf- and distant-dependent detection (Efford & cies can also present a monitoring fered area. This approach was taken: (i) to Fewster 2013). The approach is essentially challenge with single-trap cages because allow sampling across the entire safe spatial in nature and is based on the pre- individuals are particularly ‘trap happy’; haven (as we expected considerable spa- mise that each individual animal is increas- this can then introduce bias to estimates tial heterogeneity in density) and (ii) as it ingly detectable with its proximity to its of density (Royle et al. 2013). To reduce was critical for staff and animal welfare activity centre (Efford & Fewster 2013; the bias associated with the ‘trap-happy’ that cages could be quickly and effectively Royle et al. 2013). nature of woylies, a spatially explicit cap- checked and cleared. Within each site, the The use of SECR techniques with sin- ture–recapture (SECR) modelling two or four cages were positioned within gle-catch traps has the potential to intro- approach (Efford 2016) was used to esti- 10 m of each other. Each trap was duce additional bias to estimates of mate population size. The SECR approach weighted down, half-covered with a hes- population size; this is because the statistically accounts for biases relating to sian bag and baited with universal bait approach assumes all traps are always ‘trap happiness’ (Royle et al. 2013) and (peanut butter and rolled oats). Traps available to individuals of the target spe- can be used to easily model spatial varia- were set between 16:00 and 18:30 AWST cies over the sampling period (Royle tion in density. each evening (i.e. just prior to sunset). et al. 2013). Although this is clearly not Trapping was conducted over a period Traps were cleared twice per night in the case for single-catch traps, some initial of nine days in July 2017 and July 2018, 2017 and once per night in 2018. All traps research has found that ‘reasonable’ popu- respectively. In each trapping session, were finally cleared, and all animals were lation size estimates can nevertheless be

ª 2020 Ecological Society of Australia and John Wiley & Sons Australia, Ltd ECOLOGICAL MANAGEMENT & RESTORATION 3 RESEARCH REPORT made for some species (Distiller & Borch- centres, trap deployment details, animal Trapping ers 2015). Including multiple traps at each capture details and the area that is associ- site and/or checking traps twice per night ated with each potential home range cen- In 2017, 121 woylies (75 males:46 (i.e. effectively mimicking multiple catch tre pixel. A trap response, spatial or non- females) were captured and the maximum cages), allowed an improvement in capac- spatial model, and either a half-normal or distance an individual moved between ity of the SECR approach to estimate woy- negative exponential detection function capture sites was 7.3 km. All models per- lie population size. (Gopalaswamy et al. 2012) can be chosen. formed well and converged (Table S1). Package SPACECAP (Gopalaswamy Finally, as the analysis is a Bayesian data For all models, there was significant indi- et al. 2012), initiated through R software augmented model (Royle et al. 2013), cation of a positive trap response by woy- (R Core Team 2013), was used to analyse the user must enter the number of MCMC lies (95% credibility intervals did not the data. SPACECAP is a simple but robust iterations, the burn-in period, the thinning include zero), as reflected in the increased R package developed for SECR analysis by rate and the augmentation level (Gopalas- detectability of an individual after its first Gopalaswamy et al. (2012) that performs wamy et al. 2012). Models with different capture (Table S1). The density and popu- the Bayesian data augmented models that detection functions and home range spac- lation size estimates from each model were originally developed by Royle et al. ing (25, 50 and 100 m) were run to assess were similar, regardless of pixel density; (2009). Gopalaswamy et al. (2012) pro- their impact on the estimated population however, the negative exponential detec- vide a detailed description of SPACECAP, size. Note that 25 m is equivalent to tion function consistently produced its use and its statistical underpinnings. 0.000625 km2, 50 to 0.0025 km2 and slightly smaller estimates (Fig. 2). The package uses a hierarchical model 100 to 0.01 km2. In 2018, 253 woylies (165 males:88 that incorporates an observation and a N(S) (the population size) is an esti- females) were captured and the maximum state process (Royle et al. 2009). The state mate of the number of activity centres distance an individual moved between process models density and individual located within S. Density is calculated as capture sites was 14.6 km, with mean activity centres, where the location of an D = N(S)/||S||. ||S|| is the state-space area. movement of 2.25 km (SD = 3.32 km). individual (i) is defined by si ~ Uniform k0 is the expected encounter rate of an All models converged (Table S1) well (S). si (1, 2,..,N) represents individual ani- individual [i,j,k] with an activity centre but the Bayesian P-values for the models mal activity centres that are distributed exactly at the site. r (or 1/b2) can be inter- with a half-normal detection function indi- randomly over region S. As described by preted as a mean ‘range’ parameter that is cated a poor fit. The population and den- Gopalaswamy et al. (2012), SPACECAP scaled according to Borchers and Efford sity estimates were consistent across incorporates binary observations (yijk) col- (2008). pixel densities for each detection func- lected from multiple individuals (i) at mul- SPACECAP automatically generates out- tion. As with 2017, the negative exponen- tiple sites (j) across multiple repeated puts that allow assessment of the model; tial models predicted a smaller population visits (k). yijk ~ Bernoulli(pijk), where pijk these include a Bayesian P-value (Gopalas- size than did the half-normal models. is the probability of detecting individual i wamy et al. 2012 provide details relating Given the models with the negative expo- at site j on visit k. Also, SPACECAP uses to the generation of the Bayesian P-value) nential detection function had better fit in the complementary log–log link transfor- that should be around 0.5 for an adequate 2018, we report on the models with a mation (cloglog(pijk) = b0), where b0 is model fit. To evaluate convergence, negative exponential function and a 25- the inverse of the cloglog transformation: SPACECAP provides the Geweke’s diag- m grid spacing (or 0.000625 km2 pixel

eb0 nostic (Geweke 1992) and a z-score of area). Of note, in 2018, 47 individuals pi;j;k ¼ 1 e the diagnostic. Absolute z scores <1.6 were recaptured (from 2017), all of which

Under a Poisson model, pijk is the prob- or >1.6 indicate a lack of convergence. were male. ability that individual i is captured by a The mean ‘range parameter’ estimate can The population estimate from 2017 trap at site j on visit k (Royle et al. be thought of as an estimate of the average was 241 animals (95% CI: 180–300), with 2009). SPACECAP allows the modelling amount of movement around each activity an average density of 3.09 woylies/km2 of (i) the probability of capture up to centre, such that animals that move fur- (95% CI: 2.34–3.88). The population esti-

(b0) and after (b1) ﬁrst capture of individ- ther away from their activity centres will mate from 2018 was 758 (95% CI: 566– ual i at site j; and (ii) change in the effect have a larger mean range parameter esti- 989), with an average density of of distance between an individual’s activ- mate (Gopalaswamy et al. 2012). 9.95 woylies/km2 (95% CI: 7.35–12.94; ity centre and site location (b2). SPACE- Fig. 3). The mean range parameter CAP employs either a half-normal or a decreased from 721.8 (95% CI: 642.2– negative exponential link function (Royle Results 799.6) in 2017 to 621.5 (95% CI: 543.3– et al. 2009) and improper uniform priors. 676.7) in 2018, indicating that individual Translocations Positive parameters are Uniform(0,∞), activity areas decreased over time. and others are Uniform(∞,∞). No mortality occurred during the translo- In 2017, mean predicted pixel density SPACECAP requires the provision of a cation process, nor whilst individuals estimates across the various habitat types data ﬁle with potential home range were wearing radio-tracking collars. (Fig. S2) were reasonably similar, but

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Discussion In addition to creating a new population for future reintroductions, the primary aim of the reintroduction of woylies to Mt Gibson was to increase the overall area of occupancy, extent of occurrence, number of sub-populations and global population size of the species (Ruykys & Kanowski 2015). A new population has now been established at Mt Gibson that is growing in size and spreading across the available area. Although the translocation is still in its early phase in terms of a typical reintroduction time frame (i.e. it may take decades to ensure a viable and Figure 2. Estimate of woylie population size at Mt Gibson in 2017 and 2018 for different pixel genetically diverse population has been densities and detection functions. Vertical lines indicate 95% credibility intervals. Note that, for established), the key long-term success cri- ease of interpretation, pixel densities have been jittered and reported in metres between each terion for Mt Gibson is that by 2021 there pixel. A distance of 25 equals a pixel density of 0.000625 km2; 50 equals a pixel density of will be a population of woylies with a min- 0.0025 km2; and 25 equals a pixel density of 0.001 km2. imum of 300 individuals (Ruykys & Kanowski 2015). This criterion is well on its way to being met. At this stage, it is uncertain just how large the population at Mt Gibson will be or how much it will oscillate over time. Understanding population size and its vari- ability with a view to quantifying and managing a viable carrying capacity is a critical goal of any translocation (Robert et al. 2015). The long absence of woylies from Mt Gibson or similar environments makes it challenging to develop a management regime based on a target density range; however, the concurrent monitoring of woylie density and other system elements and processes will provide an evidence base on which to evaluate the impacts of woylie population size on their habitat. Collection of these data, and understanding of the processes driving change in this system, should eventually facilitate adoption of a mature theory of management for the woylie population at Figure 3. Map of predicted woylie density in the Mt Gibson safe haven in 2017 and 2018, based on models that included a trapping response covariate, a negative exponential detection Mt Gibson (e.g. Van Wilgen et al. 1998). function and 0.000625 km2 (25-m spacing) pixel density. Density is the predicted number of indi- Based on the results reported here, we viduals per square kilometre. can see that woylies can occupy the majority of the safe haven and, given a reduction in the mean range parameter, slightly higher in mallee, saltbush and 2018, mean predicted pixel density esti- individual activity areas appear to be York Gum woodland habitats (Fig. 4). mates across the various habitat types decreasing with population size (as has Saltbush habitats are geographically lim- were similar, with the exception of the been shown for other macropods; Viggers ited, with the only patch occurring in saltbush habitat, which maintained its & Hearn 2005). Thus, it will be particu- the north–eastern area, where woylies comparatively high mean density larly important to identify, monitor and, were also in high densities in 2017. By (Fig. 4). where possible, manage key threatening

ª 2020 Ecological Society of Australia and John Wiley & Sons Australia, Ltd ECOLOGICAL MANAGEMENT & RESTORATION 5 RESEARCH REPORT

vegetation structure and composition along with other key system elements and risk factors. We also note that, given the changes in range parameter, infer- ences about home range size and habitat use made from shorter-term radio-tracking studies should be viewed with suitable caution. Finally, by adapting a standard single-catch cage trapping method and applying the SECR modelling approach, we were able to generate estimates of the population size (and associated uncertainty) of a species that is known to be ‘trap happy’. We suggest that this approach could be trialled on other populations of woylies and on other species Figure 4. Mean predicted pixel density for each habitat type within the safe haven in 2017 and that present similar challenges. By using 2018. Vertical lines indicate standard deviation. a simple-to-use R software package, we feel that the approach can be easily adopted by people and organisations that processes, including those that relate to may indicate that there is a male bias in lack significant statistical expertise, but the possibility of over-population (e.g. the population. Alternatively, it is also pos- with confidence that the outputs can be see Linley et al. 2017). As a first step to sible that, using this approach, males are checked and assessed appropriately. managing threatening processes, AWC more trappable than females (note that a ecologists conducted a structured expert- similar approach used at Karakamia typi- Acknowledgements based risk assessment for the Mt Gibson cally results in a slightly female-biased safe haven in 2016 (unpublished), follow- sex ratio, AWC unpublished data, 2020). This work was conducted under the Wes- ing the approach of Smith et al. (2015) If the latter is correct, then population size tern Australian Department of Biodiversity, and Smith et al. (2019). The risk assess- will have been underestimated and further Conservation, and Attractions Animal ment identified several direct risk factors work may be required to address that Ethics Committee permit number 2015/ and their associated system process for issue. If the former is correct, the male 10 and under an approved translocation monitoring. Disease and the availability bias may eventually dissipate, the popula- proposal. Funding was from AWC support- of food were believed to be particularly tion may be male-biased and will remain ers, Lotterywest, Perth Zoo, the National important risk factors for woylies. Should so, and/or further research to determine Landcare Programme and the Northern over-population of woylies occur, food the cause of the bias may be warranted. Agricultural Catchments Council. The availability may decrease and disease out- research reported here was also partly breaks may become more likely (e.g. Her- funded by the Australian Government’s Conclusion man 1969). Additionally, with over- National Environmental Science Pro- population of one of the reintroduced AWC has established a population of the gramme through the Threatened Species grazing species, the safe haven’s vegeta- endangered woylie within Mt Gibson Recovery Hub. We would especially like tion elements might be negatively Wildlife Sanctuary’s safe haven. Reintro- to thank Dr Manda Page and Keith Morris impacted, with possible cascading effects duced individuals had high survivorship from DBCA for their advice and assistance for many different faunal elements, includ- and, given the increases in population in planning the translocations and staff ing woylies, via changes to the availability size, have clearly recruited into the popu- from both DBCA Upper Warren and White- of habitat and food (e.g. Ripple & Beschta lation. The species now also occupies man Park for assistance in translocations. 2012). Regularly measuring woylie popu- most of the safe haven and, as such, the Thanks are also extended to previous and lation size will allow AWC to monitor site is on track to becoming an extra insur- current AWC science and operational staff, the species’ density and distribution. ance population. The population also volunteers and supporters for their contri- In terms of the monitoring of woylies, increases the species’ overall extent of butions, with a special acknowledgement we found the approach of having more occurrence, number of sub-populations of John Kanowski, Laura Ruykys, Noel traps per site, but with a single check, to and global population size. By developing Riessen, Fay Lewis, Mel Farrelly, Bradley be more manageable (as opposed to multi- a robust monitoring approach, ongoing Gale, Edward Ellis, Dean Portelli, Kelly ple checks per night). The male-biased assessment of population size can occur Woolerton, Kaarissa Harring-Harris and inter-annual recapture rates and sex ratio in conjunction with monitored change in Carlie Armstrong.

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