Western Ringtail Research Articles

Captive-raised western ringtail possum (Pseudocheirus occidentalis) with a bold personality have higher survival rates when released into the wild

We tested if the personality of captive-raised western ringtail possums (Pseudocheirus occidentalis), and the impact of other variables would influence their survival after release using radiotelemetry. We hypothesised a greater survival for individuals: (i) bold; (ii) habituated in advance to food collected from the release area; (iii) juveniles instead of adults, because more easily tolerated by wild individuals, and (iv) released in new dreys (nests) as they would not have the strong odour of old dreys and would be less attractive to foxes. After 3 months of radio tracking, out of 143 possums released, 79 died: 51 (64.6%) were preyed upon by European red foxes (Vulpes vulpes). Bold or female individuals had higher survival rates than shy or male individuals (survival rate bold: 53%, shy: 41%, p = 0.046, hazard ratio = 0.352, 95% CI HR [0.126, 0.979]; survival rate females: 44%, males: 35%, p = 0.007, hazard ratio = 2.811, 95% CI HR [1.322, 5.976]). Shooting was a more effective fox control strategy to improve survival compared to baiting (p = 0.019, hazard ratio = 0.167, 95% CI HR [0.038, 0.742]). Our results demonstrate that the control of introduced predators is critical for the success of reintroductions of this critically endangered species.

Use of wildlife-friendly structures in residential gardens by animal wildlife: evidence from citizen scientists in a global biodiversity hotspot

Private gardens comprise a large component of greenspace in cities and can offer substantial conservation opportunities. There has been strong advocacy from researchers, policymakers, and conservation practitioners to engage householders in wildlife-friendly gardening practices to increase the quantity, quality and connection of habitat resources for urban wildlife. Despite this call to action, there remains limited knowledge on the use and benefit of some wildlife-friendly structures within gardens, such as artificial refuges and water sources. In collaboration with 131 citizen scientists in southwestern Australia, we examined the use of seven wildlife-friendly structure types by four vertebrate taxa groups. Following 2841 wildlife surveys undertaken between 31 July 2022 and 22 February 2023, we found that all structures were used primarily by target taxa, water sources were often used by relatively common species, certain structures such as possum shelters were used by rare and threatened species (e.g. western ringtail possum), and that there was evidence of animals making use of the wildlife-friendly structures for reproduction (e.g. bird eggs in nest boxes and tadpoles in water sources). Water sources were used more frequently and by a greater diversity of wildlife than artificial refuges. In particular, bird baths were used by the highest number of species (mainly birds) while ponds were used by the greatest variety of taxa (birds, reptiles, frogs, mammals). Our findings provide evidence-based support for the advocacy of wildlife-friendly gardening practices and further highlight the role of residential gardens for biodiversity conservation.

Practical, effective and safer: Placing traps above ground is an improved capture method for the critically endangered ngwayir (western ringtail possum; Pseudocheirus occidentalis).

The capture of wild-living animals can provide valuable information that is critical in developing and implementing effective conservation actions. These capture procedures, however, often require direct handling of individuals by researchers, and conservationists should constantly seek to improve capture methods so that the impacts on animal welfare are minimised. The ngwayir (western ringtail possum; Pseudocheirus occidentalis) is a critically endangered arboreal marsupial in need of effective conservation. It is, however, not amenable to conventional trapping, leading to the use of methods such as nest robbing and tranquilisation using dart guns or pole syringes, which involve potentially serious animal welfare risks and longer exposure of animals to humans as compared to conventional trapping. In pursuit of an improved capture method, we investigated opportunistically whether placing traps above the ground would increase the capture success rate of the species, using wire cage traps baited with universal bait and fruit. Between 2010 and 2019, we deployed trapping grids in Locke Nature Reserve and adjacent campsites near Busselton, WA, Australia, with traps placed on the ground for 1,985 trap nights and traps placed on horizontal tree branches, fallen trees or fences, 1-2 m above ground for 694 trap nights. With the above ground traps we trapped 82 ngwayirs out of 694 trap nights, 27 in autumn and 55 in spring. We also captured eleven common brushtail possums (Trichosurus vulpecula; 1.6% trap success rate), 12 King's skinks (Egernia kingii; 1.7%) and five black rats (Rattus rattus; 0.7%). Trapping success rate was higher in elevated traps (up to 18.3%) compared to traps on the ground (0.5%) and using fruit as bait increased the trap success rate. These results suggest that using elevated traps baited with fruit is a practical, effective method to capture the ngwayir.

Quantifying the direct fire threat to a critically endangered arboreal marsupial using biophysical, mechanistic modelling

AbstractHistorically unprecedented areas of forest habitat have been impacted by fire, as climate change and other anthropogenic disturbances drive increases in fire burned area and severity. Although 88% of Australia's [threatened] land mammals are threatened by inappropriate fire regimes, calculations of animal mortality resulting from specific events have been impeded by knowledge gaps relating to both the direct (first‐order) and long‐term (second‐order) effects of fire on different species. This study addresses the need for a quantified, mechanistic understanding of first‐order effects, presenting an extension of the Fire Research and Modelling Environment (FRaME) to allow prediction of species‐specific mortality. FRaME is demonstrated and tested here by replicating an incident in which a prescribed burn caused 77% mortality of a population of the critically endangered ngwayir (Pseudocheirus occidentalis, Pseudocheiridae). FRaME correctly predicted heavy mortality (62–79%) arising from partial and full‐thickness burns and asphyxiation due to burns in the respiratory tract. Mortality varied with animal fire‐avoidance strategies (p < 0.001) and the thickness of tree hollow walls (r = −0.95, p < 0.001). Although management guidelines specified low intensity fire, mortality had no significant relationship with Byram intensity and larger flames due to ‘torching’ were most frequent when fire spread was slowest. FRaME modelling predicted that individuals would be impacted by temperatures exceeding 500°C for several minutes. Fire management that is premised on discredited notions of fire behaviour and overly simple models can lead to catastrophic management outcomes such as those documented here. FRaME addresses this need by providing a platform to account for heterogeneous fire behaviour as well as animal behaviour and habitat quality, calculating fire risk to fauna and guiding management that maximizes safe habitat.

Critically Endangered marsupial calls residential gardens home

AbstractUrbanization is one of the biggest global threats to biodiversity. However, urban areas can offer opportunities for biodiversity conservation because of the assortment of resources and numerous taxa that occur in these habitats. While the use of gardens by animals is well documented, the ability of native fauna to exclusively use (i.e. reside in) them is largely uninvestigated and therefore constrains our current understanding of their conservation ‘value’. We aimed to determine whether individuals of a threatened species can exclusively reside in gardens for several months of their life, and the frequency that novel resources (i.e. non‐natural) are used compared to natural ones. We predicted that individuals captured in gardens would use both bushland and residential habitat, and use natural resources more frequently than novel resources because of the assumption that remnant habitat is more suitable than modified gardens. Using the Critically Endangered western ringtail possum (Pseudocheirus occidentalis) as a case study, we captured 20 individuals in gardens and radio‐tracked them for a period of 95 ± 3.3 days to determine their habitat use. Contrary to our predictions, for the duration of our study individuals exclusively resided within gardens, irrespective of proximity to bushland, and used novel resources more frequently than natural resources for all behaviours. We also found that over half (53%) of all the captured female possums had pouch young, and at the conclusion of the study, male possums were on average 43 g heavier. Our results exemplify that gardens can be of sufficient quality to support individuals, and that these modified habitats should be incorporated into conservation policy in urban landscapes. Given the extensive number of threatened species located within cities globally, our finding that a threatened species can reside exclusively within gardens further highlights the conservation opportunity that residential landscapes and cities offer wildlife.

Is the presence of a threatened arboreal mammal in residential areas related to remnant habitats?

AbstractRemnant natural habitat is assumed critical for supporting threatened animals within urban landscapes because these species generally have specific habitat requirements and typically respond poorly to anthropogenic disturbances. However, evidence that demonstrates some threatened species can occur, persist and even prosper in highly modified areas with seemingly little dependence on remnant vegetation challenges the role remnant vegetation is perceived to play in sustaining threatened species in urban landscapes. In this study, we tested the assumption that the presence of a threatened species in modified areas of an urban environment was dependent on remnant vegetation using the Critically Endangered western ringtail possum (Pseudocheirus occidentalis) as a case study. We predicted that the presence of possums in highly modified habitats would be positively correlated with proximity to remnant vegetation. Using spotlight surveys of 195 transects to determine species occurrence on residential streets, we found that the presence of the western ringtail possum was not related to remnant vegetation within the immediate surrounds, nor the distance from remnant habitats (neither large nor small). Our results promote the suggestion that highly modified habitats in urban landscapes can contribute conservation outcomes and that their potential role in wildlife conservation warrants serious consideration.

2D or not 2D? Three-dimensional home range analysis better represents space use by an arboreal mammal

For animals which utilise vertically distributed habitat resources, home ranges quantified in two-dimensions (2D) likely misrepresent space use and constrain interpretations of species' ecology and behaviour. Three-dimensional (3D) home range estimation has proved useful for understanding space use over relatively large vertical ranges (e.g. 100's of meters), yet none have applied a 3D approach to describe space use over narrower vertical ranges (e.g. meters or 10's of metres) typical for many arboreal animals. This study demonstrates 3D home range estimation for the arboreal western ringtail possum (Pseudocheirus occidentalis) using temporally resolute locations (15 min intervals) of five radio collared animals. We hypothesised that, due to the use of vertically distributed habitat resources, 3D home ranges would be more complex, spanning a range of heights, and would subsequently be larger in size compared to those estimates derived from typical 2D analysis. A comparison of 50% (core) and 95% (total) 2D kernel density and 3D kernel density utilisation distributions reveal structurally complex home ranges that span the entire vertical range of vegetated habitat. Estimates of the total 3D home range size were significantly greater than those derived from 2D analysis, and the difference in size was positively related to the vertical range of available habitat. This study establishes that 3D home range analysis can reveal information on vertical space use of arboreal species over relatively small vertical ranges, and is likely to be valuable in understanding the use and identification of key habitats and resources, as well as interactions among sympatric species.

New evidence of unexpectedly high animal density and diet diversity will benefit the conservation of the Critically Endangered western ringtail possum

AbstractA comprehensive and contemporary understanding of habitat and resource requirements has been critical to the conservation of multiple taxa and ecosystems globally. Until recently, much of the ecological knowledge that contributes to conservation priorities and strategies for the Critically Endangered western ringtail possum (Pseudocheirus occidentalis) was largely derived from decades‐old observations in peppermint (Agonis flexuosa) and marri‐jarrah (Corymbia calophylla and Eucalyptus marginanta) woodlands in the northern parts of the species range. These observations do not account for more recent evidence of their flexible use of habitat resources in other regions of its range. This may represent a significant conservation opportunity for the species through the identification of additional habitats that warrant protection. In a region where knowledge of their ecology is scarce, we used scat analysis and quantitative spotlighting to determine the diet and density of western ringtail possums in three vegetation types: peppermint, sheoak (Allocasuarina fraseriana) and marri‐eucalypt (C. calophylla, E. marginanta and Eucalyptus staerii) woodlands. Given the species’ reported dependence on peppermint woodlands and dominant canopy species for food sources, we hypothesised that western ringtail possums would be most abundant in this habitat type and that their diet would comprise the foliage of few (≤2 species) canopy species. We found western ringtail possums consumed a higher diversity of plant species than expected (8–14), exhibited dietary preference for non‐dominant canopy species and were present in all sampled vegetation types at substantially higher densities than previously recorded for the region (as high as 17 possums ha−1). Our results confirm (i) the western ringtail possum is flexible in its use of habitat resources and (ii) the significant conservation value of sheoak and marri‐eucalypt woodlands in the southernmost portion of its distribution.

Physiological implications of climate change for a critically endangered Australian marsupial

Extreme weather events (e.g. heatwaves and droughts) can expose animals to environmental conditions outside of their zones of physiological tolerance, and even resistance, and impact long-term viability of populations and species. We examined the thermal and hygric physiology of the critically endangered western ringtail possum (Pseudocheirus occidentalis), a member of a family of marsupial folivores (Pseudocheiridae) that appear particularly vulnerable to environmental extremes. Basal metabolic rate and other standard physiological variables measured at an ambient temperature of 30°C conformed to values for other marsupials. At lower temperatures, body temperature decreased slightly, and metabolic rate increased significantly at 5°C. At higher temperatures, possums experienced mild hyperthermia and increased evaporative heat loss by licking rather than panting. Their point of relative water economy (–8.7°C) was more favourable than other pseudocheirid possums and the koala (Phascolarctos cinereus). We predict that western ringtail possums should tolerate low ambient temperatures well and be more physiologically tolerant of hot and dry conditions than common (Pseudocheirus peregrinus) and particularly green (Pseudochirops archeri) ringtail possums, and koalas. Our physiological data can be incorporated into mechanistic species distribution models to test our hypothesis that western ringtail possums should physiologically tolerate the climate of habitat further inland than their current distribution, and withstand moderate impacts of climate change in the south-west of Western Australia.

Sheoak woodlands: a newly identified habitat for western ringtail possums

ABSTRACTAlthough critically endangered western ringtail possums (Pseudocheirus occidentalis) have been recorded from a variety of vegetation types in southwestern Australia, the extent to which many of these vegetation types are occupied by the species remains unknown. We conducted spotlight surveys for western ringtail possums between March and April 2018 in Albany, southwestern Australia, to determine the species’ occupancy in 2 vegetation types. Using occupancy models, we demonstrated that sheoak (Allocasuarina fraseriana) woodlands, previously unrecognized as providing western ringtail possum habitat, support the species, although the median probability of their occupancy was lower than in marri (Corymbia calophylla) and eucalypt (Eucalyptus marginata and E. staeri) woodlands. Use of trees and other habitat components by western ringtail possums varied within and between vegetation types. Sheoak woodlands are likely critical for western ringtail possums and given the apparent flexibility in vegetation types used by the species, investigation of the potential value of other vegetation types for this species has conservation merit. © 2019 The Wildlife Society.

Going to ground: implications of ground use for the conservation of an arboreal marsupial

On the basis of previous observations, the critically endangered western ringtail possum (Pseudocheirus occidentalis) has been described as strictly arboreal. Using motion-sensing cameras placed in bushland remnants and residential gardens, we demonstrate that the species uses the ground during its nocturnally active period. To acknowledge that ground use may make the species more susceptible to terrestrial predators than previously thought, we propose that the species should not be described as ‘strictly’ arboreal.

Use of urban bushland remnants by the western ringtail possum (Pseudocheirus occidentalis): short-term home-range size and habitat use in Albany, Western Australia

Management of wildlife in habitats fragmented by urbanisation requires an understanding of a species’ habitat use. Known populations of the critically endangered western ringtail possum (Pseudocheirus occidentalis) are largely restricted to bushland remnants in rapidly urbanising areas of south-western Australia. Habitat use is thought to be driven by nutritional content, structure and connectivity of canopy vegetation. At the southernmost extent of the species’ range, habitat use is largely unknown, although it is expected to be different from previous descriptions due to differences in vegetation characteristics. We used VHF and global positioning system tracking collars to determine short-term home-range size, diurnal refuge use and night-time tree use of western ringtail possums in bushland remnants within Albany City. Possums had small home ranges (0.88 ha) that were negatively correlated with percentage canopy cover; used a variety of daytime refuges (predominantly dreys); and preferentially utilised marri (Corymbia calophylla) and jarrah (Eucalyptus marginata) at night. These results confirm that differences in habitat use among populations exist and suggests that the species is reasonably flexible in its use of habitat. Management of western ringtail possums needs to be population specific and will benefit from further examination of habitat use in the variety of occupied habitats.

Recoveries and cascading declines of native mammals associated with control of an introduced predator

Invasive animal species are a major factor in the extinction and endangerment of native species worldwide. Longterm monitoring reveals some mammal recoveries have not been sustained in the presence of a broad-scale threat abatement program aimed at reducing the impact of the introduced Vulpes vulpes (red fox)-a top-order predator and key threat to many native species in Australia. Over 51,000 records of 19 terrestrial mammal species reported from a range of survey methods (pitfall traps, Elliott box traps, wire cage traps, spotlighting, sand plots, and nest boxes) across the Upper Warren region of southwestern Australia were used to investigate population changes over 41 years (1974-2014). Since the mid-1990s, populations of at least 7 native mammal species or genera have successively declined at similarly rapid rates and magnitudes (80-100%): Sminthopsis spp., Rattus fuscipes, Phascogale tapoatafa, Isoodon obesulus, Pseudocheirus occidentalis, Bettongia penicillata, and Notamacropus irma. R. fuscipes has not been recorded in the region since 2005 and may have become locally extinct. The other species that have declined remain at risk of becoming locally extinct. Three species have increased since 2000: Trichosurus vulpecula, Dasyurus geoffroii, and Notamacropus eugenii. The Upper Warren region in which this community disassembly has occurred is one of the principal sites for the conservation of many threatened mammal species and is within Australia's global biodiversity hotspot. We discuss the critical importance of long-term monitoring and the need to identify the causes of population change to inform how conservation and management activities can best be focussed. Predation by the introduced Felis catus (cat) is hypothesized as the most likely common or primary cause behind many of the recent declines in the Upper Warren. The integrated reduction of both cats and foxes, conducted within an experimental framework, is the most direct and definitive action to test this and deliver the greatest practical conservation outcomes.

Owl survey of the Peel–Harvey Estuary in south-western Australia

Little is known of owls in south-western Australia compared with the owls of southern and eastern Australia. Surveys of forest owls in the south-west are almost completely lacking. This study sought to determine the abundance and detectability of owls immediately around the Peel–Harvey Estuary in south-western Australia. The southern boobook (Ninox boobook) and the masked owl (Tyto novaehollandiae) were the only owls detected (n = 23 and n = 1 respectively), although the nocturnal tawny frogmouth (Podargus strigoides) was detected from unelicited calls on three occasions. Southern boobooks were found to be common in this area though they are reported to be in decline in south-eastern and inland Australia. Their detectability was significantly greater in August (late winter) than at other times through unelicited calls; otherwise, there were no detections in winter. A variety of small mammals were detected during the surveys, including: a little red flying-fox (Pteropus scapulatus), a western ringtail possum (Pseudocheirus occidentalis), 19 southern brown bandicoots (Isoodon obesulus), 4 common brushtail possums (Trichosurus vulpecula), 21 rabbits (Oryctolagus cuniculus), a black rat (Rattus rattus), 2 red foxes (Vulpes vulpes) and 22 microbats.

An Endangered Arboreal Specialist, the Western Ringtail Possum (Pseudocheirus occidentalis), Shows a Greater Genetic Divergence across a Narrow Artificial Waterway than a Major Road.

The fragmentation of habitats by roads and other artificial linear structures can have a profound effect on the movement of arboreal species due to their strong fidelity to canopies. Here, we used 12 microsatellite DNA loci to investigate the fine-scale spatial genetic structure and the effects of a major road and a narrow artificial waterway on a population of the endangered western ringtail possum (Pseudocheirus occidentalis) in Busselton, Western Australia. Using spatial autocorrelation analysis, we found positive genetic structure in continuous habitat over distances up to 600 m. These patterns are consistent with the sedentary nature of P. occidentalis and highlight their vulnerability to the effects of habitat fragmentation. Pairwise relatedness values and Bayesian cluster analysis also revealed significant genetic divergences across an artificial waterway, suggesting that it was a barrier to gene flow. By contrast, no genetic divergences were detected across the major road. While studies often focus on roads when assessing the effects of artificial linear structures on wildlife, this study provides an example of an often overlooked artificial linear structure other than a road that has a significant impact on wildlife dispersal leading to genetic subdivision.

An artificial waterway and road restrict movements and alter home ranges of endangered arboreal marsupial

Artificial linear structures can cause habitat fragmentation by restricting movements of animals and altering home ranges. The negative impacts of these linear structures, especially of those other than roads, on arboreal species have been rarely studied even though these species can be greatly affected because of their fidelity to the canopy. We studied the home ranges of an endangered arboreal marsupial, the western ringtail possum (Pseudocheirus occidentalis), with a focus on the impacts of a road and an artificial waterway on their movement. We radiotracked 18 females and 19 males along a major road and an artificial waterway near Busselton, Western Australia, for 3 years and estimated home ranges using an a-local convex hull (a-LoCoH) estimator. No possum crossed the road successfully during the monitoring period while one crossed the waterway. Males had a mean home range size of 0.31 ± 0.044 (SE) ha, almost double that of the females at 0.16 ± 0.017 ha. Possums near the waterway had larger home ranges (0.30 ± 0.048 ha) than those near the road (0.19 ± 0.027 ha), and the size increased with proximity to the waterway, probably due to the greater availability of nearby canopy connections and the lower availability of preferable foliage. These results demonstrate that both the road and waterway represent significant physical barriers to possums, and the artificial waterway influenced home ranges more severely than the road. This suggests that linear infrastructure other than roads can affect movements of strictly arboreal animals, and negative impacts of these structures need to be assessed and mitigated by reconnecting their habitat, just as those of roads.

A remarkably quick habituation and high use of a rope bridge by an endangered marsupial, the western ringtail possum

Rope bridges are being increasingly installed worldwide to mitigate the negative impacts of roads on arboreal animals. However, monitoring of these structures is still limited and an assessment of factors influencing the crossing behaviours is lacking. We monitored the use of a rope bridge near Busselton, Western Australia by the endangered western ringtail possums (Pseudocheirus occidentalis) in order to identify the patterns of use and factors influencing the crossings. We installed motion sensor cameras and microchip readers on the bridge to record the crossings made by individual animals, and analysed these crossing data using generalised linear models that included factors such as days since the installation of the bridge, breeding season, wind speed, minimum temperature and moonlight. Possums started investigating the bridge even before the installation was completed, and the first complete crossing was recorded only 36 days after the installation, which is remarkably sooner than arboreal species studied in other parts of Australia. The possums crossed the bridge increasingly over 270 days of monitoring at a much higher rate than we expected (8.87 ± 0.59 complete crossings per night). Possums crossed the bridge less on windy nights and warm nights probably due to the risk of being blown away and heat stress on warmer days. Crossings also decreased slightly on brighter nights probably due to the higher risk of predation. Breeding season did not influence the crossings. Pseudocheirus occidentalis habituated to the bridge very quickly, and our results demonstrate that rope bridges have a potential as an effective mitigation measure against the negative impacts of roads on this species. More studies and longer monitoring, as well as investigating whether crossing results in the restoration of gene flow are then needed in order to further assess the true conservation value of these crossing structures.

Species distribution modelling using bioclimatic variables to determine the impacts of a changing climate on the western ringtail possum (Pseudocheirus occidentals; Pseudocheiridae)

SUMMARYThe ngwayir (western ringtail possumPseudocheirus occidentalis) is an arboreal species endemic to south-western Australia. The range and population of this species have been significantly reduced through multiple anthropogenic impacts. Classified as vulnerable, the ngwayir is highly susceptible to extremes of temperature and reduced water intake. Ngwayir distribution was determined using three different species distribution models using ngwayir presence records related to a set of 19 bioclimatic variables derived from historical climate data, overlaid with 2050 climate change scenarios. MaxEnt was used to identify core habitat and demonstrate how this habitat may be impacted. A supplementary modelling exercise was also conducted to ascertain potential impacts on the tree species that are core habitat for ngwayir. All models predicted a reduction of up to 60% in the range of the ngwayir and its habitat, as a result of global warming towards the south-west of the project area, with a mean potential distribution of 10.3% of the total modelled area of 561 059 km2. All three tree species modelled (jarrah, marri and peppermint) were predicted to experience similar contractions in range throughout most of the predicted ngwayir range, although their distributions differed. Populations of ngwayir persisting outside core habitat may indicate potential conservation opportunities.

HEMATOLOGIC AND SERUM BIOCHEMICAL REFERENCE RANGES AND AN ASSESSMENT OF EXPOSURE TO INFECTIOUS DISEASES PRIOR TO TRANSLOCATION OF THE THREATENED WESTERN RINGTAIL POSSUM (PSEUDOCHEIRUS OCCIDENTALIS)

Health screening of animals before translocation is important to minimize the risk of pathogen transmission between sites and species. Reintroduction has been incorporated into management of the endangered western ringtail possum (Pseudocheirus occidentalis) to mitigate for habitat loss within the species' core range in southwestern Australia. Between November 2005 and March 2008 we screened 47 wild and 24 captive P. occidentalis and 68 sympatric common brushtail possums (Trichosurus vulpecula hypoleucus) for infectious diseases that might compromise possum survival or fecundity at translocation sites. We found no evidence that infectious disease limits translocation success, and neither possum species showed evidence of infection with Salmonella spp., Toxoplasma gondii, Leptospira spp., or Chlamydophila spp. Antigen of Cryptococcus gattii was detected in one T. v. hypoleucus but was not of pathologic significance. Hematologic and serum biochemical reference ranges were determined for 81 wild and 24 captive P. occidentalis. Site differences were identified for red blood cell count, hemoglobin, albumin, urea, and globulin, suggesting that habitat quality or nutrient intake may vary among sites. Differences between wild and captive values were found for several parameters. These data are useful for health evaluations of injured P. occidentalis and the future monitoring of wild populations.

An inland population of the common ringtail possum (Pseudocheirus peregrinus) at Black Rock Ridge, New South Wales: a preliminary ecological assessment

The common ringtail possum (Pseudocheirus peregrinus) is considered abundant throughout its distribution in eastern Australia but appears to be declining at a regional level in inland New South Wales. Previous studies of the common ringtail possum in south-eastern Australia have focussed on coastal populations and little is known about the ecology of inland populations. In south-western Australia studies of the closely related western ringtail possum (Pseudocherius occidentalis) have found that coastal populations differ from inland populations, particularly in their nesting behaviour. In this preliminary study of an inland population of the common ringtail possum at Black Rock Ridge in central west New South Wales population density has been estimated and the habitat and nesting preference assessed. Up to one ringtail per hectare and 4.5 ringtails per spotlight hour were recorded. Tree hollows appeared to be the preferred nest site, with possums seen entering hollows during spotlighting and no dreys being located. Threats to common ringtail possums at Black Rock Ridge include the isolation of the remnant ridge vegetation within an extensively cleared landscape and the associated change in fire regimes. Within this landscape there has been an extensive reduction in available habitat, and an overall lack of habitat connectivity has placed ringtail possums at an increased risk of predation.