Greater Glider Petauroides Volans Research Articles

The Relative Concentrations of Nutrients and Toxins Dictate Feeding by a Vertebrate Browser, the Greater Glider Petauroides volans.

Although ecologists believe that vertebrate herbivores must select a diet that allows them to meet their nutritional requirements, while avoiding intoxication by plant secondary metabolites, this is remarkably difficult to show. A long series of field and laboratory experiments means that we have a good understanding of the factors that affect feeding by leaf-eating marsupials. This knowledge and the natural intraspecific variation in Eucalyptus chemistry allowed us to test the hypothesis that the feeding decisions of greater gliders (Petauroides volans) depend on the concentrations of available nitrogen (incorporating total nitrogen, dry matter digestibility and tannins) and of formylated phloroglucinol compounds (FPCs), potent antifeedants unique to Eucalyptus. We offered captive greater gliders foliage from two species of Eucalyptus, E. viminalis and E. melliodora, which vary naturally in their concentrations of available nitrogen and FPCs. We then measured the amount of foliage eaten by each glider and compared this with our laboratory analyses of foliar total nitrogen, available nitrogen and FPCs for each tree offered. The concentration of FPCs was the main factor that determined how much gliders ate of E. viminalis and E. melliodora, but in gliders fed E. viminalis the concentration of available nitrogen was also a significant influence. In other words, greater gliders ate E. viminalis leaves with a particular combination of FPCs and available nitrogen that maximised the nutritional gain but minimised their ingestion of toxins. In contrast, the concentration of total nitrogen was not correlated with feeding. This study is among the first to empirically show that browsing herbivores select a diet that balances the potential gain (available nutrients) and the potential costs (plant secondary chemicals) of eating leaves. The major implication of the study is that it is essential to identify the limiting nutrients and relevant toxins in a system in order to understand feeding behaviour.

Diet of the spotted‐tailed quoll (Dasyurus maculatus) in eastern Australia: effects of season, sex and size

AbstractThe diet of spotted‐tailed quolls Dasyurus maculatus (Marsupialia: Dasyuridae) in the north‐eastern tablelands of New South Wales was investigated by faecal analysis. Medium‐sized mammals (500–6999 g) formed the bulk of the faecal content, in terms of both volume and frequency of occurrence. The most frequently consumed vertebrates were the greater glider Petauroides volans, rabbit Oryctolagus cuniculus, bandicoots Perameles nasuta and/or Isoodon macrourus, red‐necked pademelon Thylogale thetis, ringtail possum Pseudocheirus peregrinus, and brushtail possums Trichosurus vulpecula and/or T. caninus. Insects were also eaten frequently, but birds and reptiles occurred relatively infrequently in the diet. The seasonal variation in diet was marked, with insects and reptiles being consumed more frequently, and mammals less frequently, in summer than in winter. This seasonal pattern was also mirrored by the relative volumes of mammals and insects consumed. The results obtained here indicate that the spotted‐tailed quoll is an opportunistic predator, consuming a wide variety of taxa and apparently varying its diet to take advantage of short‐term fluctuations in prey abundance. The extremely high proportion of mammals in the diet identifies D. maculatus as a hypercarnivore, or meat specialist. The importance of tree hollow‐nesting mammals in the diet indicates that the preservation of hollow‐bearing trees should aid the conservation of D. maculatus. Future dietary studies of the species should sample over extensive time periods and involve concurrent monitoring of prey populations.

Assessing spatial PVA models of arboreal marsupials using significance tests and Bayesian statistics

The predictions of stochastic metapopulation models of four species of arboreal marsupial were compared to field data on patch occupancy. The species examined were the greater glider Petauroides volans, the mountain brushtail possum Trichosurus caninus, the ringtail possum Pseudocheirus peregrinus and the yellow-bellied glider Petaurus australis. The models were developed for a system of 39 eucalypt patches in southeastern Australia, embedded within an exotic plantation of radiata pine Pinus radiata. Additionally, two alternative (null) models were developed for each species: one in which it was assumed that there was no impact of fragmentation; and a second that only modeled local population dynamics with no dispersal between patches. Congruence between the probability of occupancy of patches predicted by the metapopulation model and the actual occupancy observed in the field was assessed using tests of significance based on logistic regression. The relative performance of the three competing models was assessed for each species using Bayesian statistics. The results demonstrated that the metapopulation model made reasonable predictions for the greater glider and the yellow-bellied glider. However, none of the models predicted the observed increase in population density of mountain brushtail possums and ringtail possums in patches relative to continuous forests. Incorporating edge effects and inter-specific interactions would improve the predictions for these two species.

Effects of variable-intensity logging on mammals, reptiles and amphibians at Waratah Creek, southeastern New South Wales

Populations of arboreal marsupials, small ground-dwelling mammals, reptiles and amphibians were assessed in forest before and after logging. Different levels of canopy retention were specified to estimate the effect of varying intensities of logging on these fauna. The logging treatments imposed were; unlogged, and the retention of approximately 72%, 58% and 30% of the original canopy cover. This corresponded to 62%, 52% and 21 % retention of the original tree basal area on each logged area. The objectives of the study were to determine the sensitivity of species to logging, both in terms of the intensity of the initial impact and in terms of the time to recovery following disturbance, and to develop methods for managing areas within wood production forests where special wildlife values have been identified. A total of 53 species was recorded in the 500 ha study area, only 18 (34.0%) of which were abundant enough for assessments to be made about the effects of logging. The arboreal marsupials, in particular the Greater Glider Petauroides volans, were among the species more sensitive to logging disturbance. The small, ground-dwelling mammals and the reptiles that were sampled adequately in this study appeared to be relatively unaffected by logging or they recovered quickly (most within eight years, and probably all within 10?15 years) following logging. Despite a large survey effort, insufficient data were available to assess the effects of logging on most species of frogs, although two species may have been advantaged. The species requiring management consideration include those that declined as a result of logging, but which had not recovered within eight years (the Greater Glider, the Yellow-bellied Glider Petaurus australis, the Sugar Glider P. breviceps, and the skink Niveoscincus coventryi), the species that declined in both logged and unlogged areas (the frogs Pseudophryne bibronii, Limnodynastes peronii, Geocrinia victoriana and Heleioporus australiacus), and the species for which the data were too sparse to make any assessments. It is unclear when the species most disadvantaged by integrated logging, that is, the large gliding possums, will recolonize the logged areas. The persistence of these gliders was attributed to the retention of unlogged forest within and adjacent to logged areas. This highlights the role of riparian reserves ("wildlife corridors") and filter strips in retaining residual populations of the Greater Glider and the Yellow-bellied Glider until the logged areas are suitable for recolonization, and the importance of determining the effective size for these unlogged reserves. The data were not sufficient to determine conclusively whether reduced logging intensity at the levels applied was a better option than standard logging practices for managing populations of gliding possums in these forests. The results of this study, which was conducted in a forested landscape that was multi-aged but predominantly unlogged, may not be comparable to intensively-managed forests in which there is a lower proportion of unlogged forest and where multiple logging events have occurred.