Common Ringtail Possum Pseudocheirus Peregrinus Research Articles

Facultative hyperthermia during a heatwave delays injurious dehydration of an arboreal marsupial.

Heatwaves negatively impact wildlife populations and their effects are predicted to worsen with ongoing global warming. Animal mass mortality at extremely high ambient temperature (Ta) is evidence for physiological dysfunction and, to aid conservation efforts, improving our understanding of animal responses to environmental heat is crucial. To address this, I measured the water loss, body temperature and metabolism of an Australian marsupial during a simulated heatwave. The body temperature of the common ringtail possum Pseudocheirus peregrinus increased passively by ∼3°C over a Ta of 29-39°C, conveying water savings of 9.6 ml h-1 When Ta crossed a threshold of 35-36°C, possums began actively cooling by increasing evaporative water loss and thermal conductance. It is clear that facultative hyperthermia is effective up to a point, but once this point is surpassed - the frequency and duration of which are increasing with climate change - body water would rapidly deplete, placing possums in danger of injury or death from dehydration.

The vacant planting: limited influence of habitat restoration on patch colonization patterns by arboreal marsupials in south‐eastern Australia

Many key questions remain unresolved about how biodiversity responds to temporal increases in native vegetation cover resulting from extensive restoration efforts. We quantified occupancy and colonization probability of old growth, regrowth and planted woodland patches by arboreal marsupials within Australian agricultural landscapes subject to woodland restoration over an 11-year period. Our analyses focused on the common brushtail possum Trichosurus vulpecula and common ringtail possum Pseudocheirus peregrinus. We found strong evidence of a gradient in occupancy levels ranging from highest in old growth woodland, approaching zero in plantings, with regrowth woodland intermediate between these two broad types of vegetation structure. Plantings were not occupied by either species at the outset of our investigation and were rarely colonized throughout the subsequent 10 years. We hypothesize that a lack of shelter sites in large old hollow-bearing trees is one of the key factors limiting the occurrence of plantings by cavity-dependent arboreal marsupials, suggesting a lag between planting establishment and the time required for plantings to become suitable habitat. We found the probability of colonization was positively related to the amount of vegetation cover in the surrounding landscape. Unexpectedly, colonization probability was not influenced by a temporal increase in woody vegetation cover surrounding a patch. A paucity of relationships between patch colonization and the temporal change in vegetation cover may be explained by the fact that most of the increased vegetation cover in our study landscapes over the past decade has resulted from establishment of plantings which are generally not suitable nesting habitat for arboreal marsupials. Our findings have key management implications such as emphasizing the value of old growth woodland for arboreal marsupials and of targeting restoration efforts around old growth and regrowth woodland patches, and the flawed notion of biodiversity offsets that allow replantings to compensate for clearing old growth woodland.

Effects of multiple disturbance processes on arboreal vertebrates in eastern Australia: implications for management

Habitat loss and invasive predators increasingly threaten global biodiversity. Here we use a landscape‐scale experimental approach to explore the individual and synergistic effects of logging and an invasive predator, the red fox Vulpes vulpes on two common native arboreal vertebrates (a predator and prey species) in south‐eastern Australia. We used site occupancy methods to evaluate different models evaluating the effects of site specific forest logging disturbance, lethal fox baiting and forest structural elements for explaining variation in site occupancy of a large monitor lizard Varanus varius, and a marsupial prey, the common ringtail possum Pseudocheirus peregrinus across a complex forest landscape. Site occupancy of ringtail possum was influenced by habitat resources and the structural complexity of forest, which indirectly mediated predation risk. Presence of fox baiting had no direct effect on the ringtail site occupancy. In contrast, access to prey resources and fox baiting appeared to best explain site occupancy variation in monitor lizards across the landscape. While these species are affected primarily by separate disturbances, synergistic interactions between the processes may intensify their effects. Our results demonstrate that species susceptibility to disturbance processes are highly idiosyncratic. This approach makes efficient use of integrated modelling to aid conservation management at both local and landscape levels.

Resources at the landscape scale influence possum abundance

Abstract There is increasing realization that human perceptions of a ‘patchy’ environment do not necessarily relate to that of a particular organism and ecological characteristics of land adjacent to patches of natural vegetation (‘remnants’) may influence the ecological processes within. We investigated how the distribution and abundance of resources within and surrounding 39 small remnants located within the city of Melbourne, Australia, influenced the abundance of common brushtail possums Trichosurus vulpecula (Phalangeridae) and common ringtail possums Pseudocheirus peregrinus (Pseudocheiridae), two primarily folivorous marsupials. Bayesian modelling techniques were used to relate the abundance of both possum species to estimates of den and food availability both within the remnant and within a 100‐m buffer strip extending out into adjacent residential development. We found that both brushtail and ringtail possum abundance within remnants increased with the density of potential den sites within the remnant and food availability within the surrounding landscape. Ringtail possum density within the remnant further increased with den availability within the surrounding landscape. Our results lend support to the hypothesis that, in highly modified landscapes, processes originating outside a remnant vegetation patch may influence the abundance of species within.

Sarcoptes scabiei: an important exotic pathogen of wombats

Sarcoptes scabiei is a parasitic astigmatid mite, which causes scabies in people and sarcoptic mange in mammals. Importantly, it is an emerging disease in wildlife throughout the world. The mite originates from a human ancestor and is thought to have spread to domestic and then free-living animals. Based on the recent emergence of sarcoptic mange in Australian wildlife and Aboriginal communities, it is thought that Sarcoptes scabiei was probably introduced to Australia by the Europeans and their animals. The mitochondrial genetic similarity of mites from Australian wildlife and domestic animals supports this. In Australian wildlife, sarcoptic mange has been reported in the common wombat Vombatus ursinus, southern hairy-nosed wombat Lasiorhinus latifrons, koala Phascolarctos cinereus, common ringtail possum Pseudocheirus peregrinus and in 2003 in the agile wallaby Macropus agilis. Compared with other native species, sarcoptic mange has by far its greatest impact on wombats, particularly common wombats, and is capable of causing high morbidity and mortality rates.

The conservation value of mesic gullies in dry forest landscapes: mammal populations in the box–ironbark ecosystem of southern Australia

Within the context of landscape variation in habitat quality, areas of unusually high productivity may serve as refuges for fauna during environmentally stressful periods and as sources of recruitment into less productive areas. In dry landscapes, water availability often defines habitat quality, so that drainages that concentrate run-off can facilitate relatively lush, and sometimes distinct, vegetation communities. The dry box–ironbark forests of south-eastern Australia may be such an ecosystem. Recent clearing of vegetation for agriculture and mining has eliminated 85% of the original vegetation in this area, with the fertile, alluvial soils being most affected. Fragmentation and degradation of remnant forest in this ecosystem has increased the potential importance of the remaining high-quality habitat to conservation. In this study, we tested the hypothesis that the abundance of mammals was higher in moist gullies than on dry hilltops, slopes and ridges in the box–ironbark forests of central Victoria. We compared 57 spatially paired gully and ridge sites. Habitat analyses indicated that gullies had a tree canopy height that was 51% taller than on ridges, 53% more trees with hollows in the upper bole and branches, and almost six times more very large trees. Ridges had 71% more small trees than gullies. Among marsupials surveyed, the common brushtail possum Trichosurus vulpecula and common ringtail possum Pseudocheirus peregrinus were significantly more abundant in gullies. Nearly all the reproduction observed in these two species occurred in gullies. The yellow-footed antechinus Antechinus flavipes was also significantly more abundant in gullies; numbers of the sugar glider Petaurus breviceps differed little. Whereas gullies occupy a very limited total area in this ecosystem, they may nonetheless be critical to some species of mammals that can survive in dry habitats but thrive only in mesic areas. Given the precariously degraded state of the box–ironbark ecosystem as a whole, protection of gullies from proposed alluvial gold mining and timber harvesting could have a disproportionate benefit to biodiversity conservation.

The conservation of arboreal marsupials in the montane ash forests of the central highlands of Victoria, South-east Australia, IV. The presence and abundance of Arboreal marsupials in retained linear habitats (wildlife corridors) within logged forest

Arboreal marsupials were censused in 49 retained linear habitats (wildlife corridors) that were excluded from timber harvesting in mountain ash Eucalyptus regnans F. Muell. and alpine ash E. delegatensis R. T. Bak. forests in the Central Highlands of Victoria, south-eastern Australia. The study sites varied in mean width from 30 to 264 m and were bounded by clearfelled and regenerated forests that were aged four years or younger. Of the 402 large trees with hollows that were measured and censused on the 49 study sites, a total of 69 animals was observed from 54 occupied trees, giving one occupied tree per 7·4 trees that were watched. The species of arboreal marsupials recorded during the study included greater glider Petauroides volans Kerr, mountain brushtail possum Trichosurus caninus Ogilby, feather-tail glider Acrobates pygmaeus Shaw, common ringtail possum Pseudocheirus peregrinus Boddaert, yellow-bellied glider Petaurus australis Shaw, sugar glider Petaurus breviceps Waterhouse and Leadbeater's possum Gymnobelideus leadbeateri McCoy. P. volans and T. caninus were the most commonly observed species and accounted for 78% of the animals seen. These species may survive better, at least in the short term, than others in linear strips that are retained after timber harvesting. Colonial and social species of arboreal marsupials that consume widely dispersed food such as saps and gums were uncommon, as predicted by the theory of central place foraging. The presence and abundance of arboreal marsupials in retained linear strips were compared with predictions from models of the habitat requirements of these species developed from sites in contiguous forest. These comparisons revealed that the presence of P. volans, P. breviceps and P. australis in retained linear strips was not significantly different from predictions derived from measures of the suitability of habitat in such areas. T. caninus was recorded at fewer sites than predicted, although the abundance of the species when present was not different from expected values. The endangered G. leadbeateri was recorded only once during the study, despite many sites providing apparently suitable habitat. Retained linear strips supported a significantly lower total abundance of arboreal marsupials than predicted from measures of habitat suitability. A combination of habitat parameters and other measured attributes of retained linear strips such as width and length were used to explain the variation in the presence and abundance of arboreal marsupials. The presence of T. caninus was influenced significantly by the number of trees with hollows and by the length of the site. P. volans was most likely to occur on sites with many trees with hollows, a westerly aspect and where there was no watercourse. Sites with the highest probability of supporting any species of arboreal marsupial occurred in E. regnans forests with numerous trees with hollows and which spanned the topographic sequence (e.g connected a ridge to a gully). The implications of our findings for the use, design and location of strips of retained linear habitat in timber production forests are discussed.

Preliminary Microscopic Investigations of the Digesta Derived From Foliage of Eucalyptus-Ovata (Labill) in the Digestive-Tract of the Common Ringtail Possum, Pseudocheirus-Peregrinus (Marsupialia)

A method is described that stabilizes vacuolar tannins in unchewed leaves of Eucalyptus ovata. This method, with light microscopy and electron microscopy, was used to study the fate of digesta in the gut of the common ringtail possum Pseudocheirus peregrinus. Normal animals (fed fresh foliage and practising coprophagy) were compared with animals denied access either to fresh foliage or to soft faecal pellets in the week before they were killed. Both manipulations appear to disturb gut function and create a need for caution in interpreting the observations. Nonetheless the results demonstrate some tanning of leaf cytoplasts in the ringtail possum, but the quantitative significance of the dietary losses so incurred is difficult to estimate. Partial digestion of cell walls and tanned cytoplasts occurs in the caecum, where massive populations of micro-organisms become attached to digestion-resistant tissue components. These 'microbial rafts' are reingested as soft pellets by coprophagy and the bacteria largely digested.

Histology and scanning electron microscopy of the development of the reproductive tract of the Common Ringtail Possum Pseudocheirus peregrinus (Pseudocheiridae: Marsupialia).

This paper describes the histological development of the reproductive tract of the female Common Ringtail Possum Pseudocheirus peregrinus. Scanning electron microscopy of the lumen of the Fallopian tubes and the uteri shows that the cells lining these tubes are ciliated or covered with microvilli. The lumenal configuration of these cells is polygonal. The development of the cilia, microvilli and well defined muscle layers found in the mature females, began in the juvenile. This sequence of differentiation indicates that the histological arrangement of the reproductive tract is associated with the onset of maturation, ovulation, pregnancy and birth of the young. This paper complements information presented in an earlier paper (Armati-Gulson and Lowe 1984) .