Leadbeater's Possum Research Articles

Reproduction in a population of the endangered Leadbeater's possum inhabiting lowland swamp forest

AbstractDenning groups (colonies) of Leadbeater's possum Gymnobelideus leadbeateri inhabiting nest boxes in lowland swamp forest were characterized by the presence of only a single breeding pair. The percentage of adult females and males in the population that held the position of ‘resident breeding individual’ within their colony was 66±12 and 62±13%, respectively. The remaining animals were mainly younger adults yet to acquire breeding positions within established colonies. Male and female Leadbeater's possums that attain breeding status within a colony usually reproduced for more than 3 years. Breeding vacancies that arose following the death of an individual were quickly filled by immigrants from neighbouring colonies. Typically, both male and female possums did not commence breeding until they were more than 2 years of age and had dispersed from their natal colony to a neighbouring group. Births were recorded in every month, with no discernible peaks in reproductive activity. This is the first reported case of aseasonal reproduction by a small petaurid species in temperate Australia. The mean litter size was 1.55, and females typically produced two litters per year. The reproductive ecology of Leadbeater's possum differs from that of other small (<260 g), communally denning petaurids in temperate Australia in the following respects: (1) first breeding occurs when individuals are older, (2) breeding occurs throughout the year, (3) the natality rate per female is higher and (4) at any time, reproduction appears to be restricted to a single pair of animals within each colony.

Wonders from down under

Many an eighteenth century gentleman's 'cabinet of curiosities' found its way into the collections that became national museums in the following century. And some of the most curious of curiosities came from Australia. Danielle Clode's Continent of Curiosities takes a similarly eclectic approach to the current exhibits in one of Australia's oldest museums, the Museum Victoria in Melbourne, as a way of telling the story of natural history in the country. Nature asked a London-based Australian to review the book, Leadbeater's possum and all.

Evaluation of PVA Models of Arboreal Marsupials: Coupling Models with Long-term Monitoring Data

This paper reports the outcomes of a novel inter-twining of long-term monitoring data and population modelling to assess the accuracy of predictions of a Population Viability Analysis (PVA) model. In particular, the relative effectiveness of different management options for reserving areas from timber harvesting was assessed for two forest-dependent arboreal marsupials, the greater glider (Petauroides volans) and Leadbeater's Possum (Gymnobelideus leadbeateri). We used data from 7 years of monitoring conducted at 161 sites to assess and modify, where appropriate, previous population models of the two species of arboreal marsupials. The results indicated that the importance of food resources for both had been underestimated in past work. Despite this, the modified models that included increased importance of food availability did not change the predicted risks of decline substantially, particularly for Leadbeater's Possum. Importantly, past conclusions about the optimal sizes of patches to reserve within the forests used wood production were robust to changes in the model. This is a valuable finding because the work we report is one of the first to empirically test the robustness of the relative predictions of a PVA model. Nevertheless, the new insights we derived from this study have implications both for: (1) the implementation of our ongoing long-term monitoring study, in particular the value of what can be termed ȁ8adaptive monitoring', and, (2) the establishment of a new silvicultural experiment designed to better create habitat for arboreal marsupials within logged and regenerated sites.

Salvage Logging in the Montane Ash Eucalypt Forests of the Central Highlands of Victoria and Its Potential Impacts on Biodiversity

The two major forms of disturbance in the montane ash eucalypt forests of the Central Highlands of Victoria (southeastern Australia) are clearfell logging and unplanned wildfires. Since the 1930s wildfire has been followed by intensive and extensive salvage-logging operations, which may proceed for many years after a wildfire has occurred. Although applied widely, the potential effects of salvage logging on native flora and fauna have been poorly studied. Our data indicate that the abundance of large trees with hollows is significantly reduced in forests subject to salvage harvesting. This has implications for thepersistence of an array of such cavity-using vertebrates as the endangered arboreal marsupial, Leadbeater's possum (Gymnobelidues leadbeateri). Salvage logging also reduces the prevalence of multiaged montane ash forests--places that typically support the highest diversity of arboreal marsupials and forest birds. Limited research has been conducted on the effects of salvage logging on plants; thus, we constructed hypotheses about potential impacts for further testing based on known responses to clearfell logging and key life history attributes. We predict many species, such as vegetatively resprouting tree ferns, will decline, as they do after clearfelling. We also suggest that seed regenerators, which typically regenerate well after fire or conventional clearfelling, will decline after salvage logging because the stimulation for germination (fire) takes place prior to mechanical disturbance (logging). Understoryplant communities in salvage-logged areas will be dominated by a smaller suite of species, and those that are wind dispersed, have viable soil-stored seed remaining after salvage logging, or have deep rhizomes are likely to be advantaged. We recommend the following improvements to salvage-logging policies that may better incorporate conservation needs in Victorian montane ash forests: (1) exemption of salvage logging from some areas (e.g., old-growth stands and places subject to only partial stand damage); (2) increased retention of biological legacies on burned areas through variations in the intensity of salvage logging; and (3) reduction in the levels of physical disturbance on salvage-logged areas, especially through limited seedbed preparation and mechanical disturbance.

A role for nest boxes in the conservation of Leadbeater's possum (Gymnobelideus leadbeateri)

A combination of fires and logging mean that more than 80% of the montane ash forests inhabited by Leadbeater’s possum (Gymnobelideus leadbeateri) in the Victorian Central Highlands consist of ecologically young stands possessing few trees with hollows. As a consequence, there have been predictions of a substantial decline in Leadbeater’s possum populations over the next 40 years. If this is to be averted, or reduced in extent, then an immediate means of increasing den site availability for the species is required. The results of a recent investigation into nest-box use by the species in lowland swamp forest demonstrate that high rates of occupancy can be achieved by targeting established colonies at sites where the vegetation structure is suitable for box installation. This suggests that nest boxes can be an effective means of increasing den-site availability for the possum, and therefore have considerable potential to contribute to the species’ conservation in the short term. Such measures should be applied in conjunction with altered forestry practises that better provide for the retention and future provision of mature hollow-bearing trees.

A set of microsatellite markers for an endangered arboreal marsupial, Leadbeater's possum

AbstractLeadbeater's possum is a small, cryptic nongliding petaurid, which is threatened by habitat loss due to the collapse of large hollow‐bearing trees and ongoing timber production in Victoria's central highlands. The recent decline of this species and the difficulties faced by researchers collecting field data has prompted the development of a suite of polymorphic microsatellite markers for application to the continuing conservation of the Leadbeater's possum.

Forests of Ash: An Environmental History. By Tom Griffiths. Cambridge, England: Cambridge University Press, 2001. 272 pp. Illustrations, photographs, maps, bibliography, index. Cloth $55.00, paper $18.95

Part I. A History of the Ash Range: 1. Continent of fire 2. Tall trees 3. 'Improving' 4. Crossing the Blacks' Spur 5. Mining 6. Timber tramways 7. Water 8. The theatre of nature 9. Tourism 10. Black Friday 11. The long experiment 12. Heritage Part II. Spotlights Ash and ants Alan Yen Co-evolution, a tall forest story Ken Walker Lyrebird Rory O'Brien Coranderrk calendar Lindy Allen Gems in the forest Bill Birch The good oil Gary Presland Hairstreak butterfly Ross Field Shortfin eel Martin Gomon 'The strength and beauty of the mountain valleys' Elizabeth Willis Leadbeater's possum Joan Dixon Insect outbreaks Alan Yen Exhibiting the tall forests Luke Simpkin Epilogue.

The use of nest boxes by arboreal marsupials in the forests of the Central Highlands of Victoria

The results are reported of a nest-box study conducted in two locations in the mountain ash (Eucalyptus regnans) forests of the Central Highlands of Victoria (south-eastern Australia) to compare usage of different nest-box designs located at different heights in trees. A total of 96 nest boxes was established using a rigorous experimental design – two regions (Powelltown and Toolangi State Forests), two forest age classes (20-year post-logging regrowth and 60-year fire- and salvage-logging regrowth), two nest-box designs (large boxes with large entrance holes and small boxes with small entrance holes), and two heights at which nest boxes were attached to trees (3 m and 8 m above the ground). The study entailed setting out four nest boxes at each of 24 sites to meet the design criteria. Evidence of occupancy by vertebrates was recorded in a total of 19 of 96 boxes on 11 of 24 sites site during regular inspections over more than three years. Thirteen boxes were used by Leadbeater's possum (Gymnobelideus leadbeateri), six by the mountain brushtail possum (Trichosurus cunninghami) and seven by the common ringtail possum (Pseudocheirus peregrinus). The common ringtail possum and mountain brushtail possum were seen only in high–large boxes but Leadbeater's possum used all but the low–large boxes. There was evidence of spatial dependence in usage patterns, with all four boxes at a given site showing signs of eventually being occupied. Only two nest boxes located in mountain ash forest regenerating after the 1939 wildfires were occupied. Relatively limited use of nest boxes supports concerns about the use of a nest box over large scales and long timeframes as an effective recovery tool for species threatened by the loss and subsequent shortage in the numbers of naturally occurring hollows.

Comment — Economics of a nest-box program for the conservation of an endangered species: a re-appraisal

Spring et al. (D.A. Spring, M. Bevers, J.O.S. Kennedy, and D. Harley. 2001. Can. J. For. Res. 31: 1992–2003) recently published a paper on the economics of a nest-box program for the endangered arboreal marsupial, Leadbeater's possum (Gymnobelideus leadbeateri) in southeastern Australian forests. While their paper is a useful one, there are some important limitations of nest-box programs that need to be highlighted. In the case of Leadbeater's possum, we have undertaken extensive nest-box studies in Victoria mountain ash (Eucalyptus regnans F. Muell.) forests, where the vast majority of populations of the species now occur. Although large numbers of nest boxes have been deployed, very few have actually been occupied, which is a major problem since the effectiveness of any nest-box program will depend on patterns of use by the target species. Given very low levels of nest-box occupancy, harvesting regimes such as those that lead to on-site tree retention are needed to better conserve hollow-dependent species like Leadbeater's possum. Moreover, the need for nest boxes in the first place indicates that logging practices are presently not ecologically sustainable, and modified forestry practices need to be adopted.

A survey design for monitoring the abundance of arboreal marsupials in the Central Highlands of Victoria

We describe a non-standard sample design for monitoring the abundance of arboreal marsupials in the montane ash forests of the Central Highlands of Victoria, south-eastern Australia. The survey design is based on overlapping and rotating sampling from a given population of sites—in this case 160 sites, each measuring 1 ha in size. Estimates of population sizes are obtained using a model-based statistical analysis. Results so far reveal considerable year-to-year variability in populations of Leadbeater's Possum ( Gymnobelideus leadbeateri), the Mountain Brushtail Possum ( Trichosurus cunninghamii), and the Greater Glider ( Petauroides volans). There appears to be an initial decline in the numbers of Leadbeater's Possum, an increase in the Mountain Brushtail Possum and no change in the Greater Glider and the total number of arboreal marsupials. It will be possible report more substantive findings about long-term trends after several more years of the program. Relationships between current and past counts for Leadbeater's Possum and Mountain Brushtail Possum were very weak. This result appeared to be due to low levels of site fidelity for these two species.

The influence of time since fire and distance from fire boundary on the distribution and abundance of arboreal marsupials in Eucalyptus regnans-dominated forest in the Central Highlands of Victoria

The impact of time since fire after two consecutive wildfires 44 years apart (1939 and 1983) within the same area, and the distance from the fire boundary (<100 m or 500-2000 m), were investigated in relation to the distribution and abundance of arboreal marsupials in 1994. Arboreal marsupials were censused by stagwatching and spotlighting in two relatively young age classes of mountain ash (Eucalyptus regnans) dominated forest in the Central Highlands of Victoria. Five species of arboreal marsupial were detected, but only three were detected in sufficient numbers to determine habitat preferences. Petauroides volans (greater glider) was statistically more abundant in 1939 regrowth forests, while Trichosurus caninus (mountain brushtail possum) showed no significant preference for either age class of forest. All but one record of Gymnobelideus leadbeateri (Leadbeater's possum) came from young forest, though the effect of age-class was not statistically significant. Distance from fire boundary explained little or no variation in mammal distribution or abundance. While the actual number of hollow-bearing trees was similar in both age classes of forest, the long-term lifespan of hollow-bearing trees in more recently burnt forest is predicted to be lower than in unburnt or not recently burnt forest. Post-fire salvage logging following the 1983 wildfires appears to have reduced the number of hollow-bearing trees at sites burnt in 1983.

Economics of a nest-box program for the conservation of an endangered species: a reappraisal

An optimization model is developed to identify timing and placement strategies for the installation of nest boxes and the harvesting of timber to meet joint timber–wildlife objectives. Optimal management regimes are determined on the basis of their impacts on the local abundance of a threatened species and net present value (NPV) and are identified for a range of NPV levels to identify production possibility frontiers for abundance and NPV. We apply the model to a case study focusing on an area of commercially productive mountain ash (Eucalyptus regnans F. Muell.) forest in the Central Highlands region of Victoria, Australia. The species to be conserved is Leadbeater's possum (Gymnobelideus leadbeateri McCoy), which is locally limited by a scarcity of nesting hollows. The modeling is exploratory but indicates that nest boxes may offer a promising population recovery tool if consideration is taken of their placement and areal extent through time.

Imidacloprid treatment of marsupials for fleas (Pygiopsylla hoplia).

Two eastern barred bandicoots (Perameles gunnii), two eastern quells (Dasyunrus viverrinus), four fat-tailed dunnarts (Sminthopsis crassicaudata), a Leadbeater's possum (Gymnobelideus leadbeateri), a yellow-bellied glider (Petaurus australis), and a ring-tailed possum (Pseudocheirus peregrinus) were treated with imidacloprid (10.7 +/- 0.6 mg/kg topically, minimum dose 0.5 mg) after observation of fleas (Pygiopsylla hoplia) on animals and in their nest boxes. No live fleas or adverse reactions to imidacloprid were observed for 27 days following treatment. The ease of application, absence of toxicity, and long residual effect makes imidacloprid a useful drug for treating flea infestations in these marsupials.

Economics of a nest-box program for the conservation of an endangered species: a reappraisal

An optimization model is developed to identify timing and placement strategies for the installation of nest boxes and the harvesting of timber to meet joint timber–wildlife objectives. Optimal management regimes are determined on the basis of their impacts on the local abundance of a threatened species and net present value (NPV) and are identified for a range of NPV levels to identify production possibility frontiers for abundance and NPV. We apply the model to a case study focusing on an area of commercially productive mountain ash (Eucalyptus regnans F. Muell.) forest in the Central Highlands region of Victoria, Australia. The species to be conserved is Leadbeater's possum (Gymnobelideus leadbeateri McCoy), which is locally limited by a scarcity of nesting hollows. The modeling is exploratory but indicates that nest boxes may offer a promising population recovery tool if consideration is taken of their placement and areal extent through time.

Factors at multiple scales affecting distribution patterns and their implications for animal conservation - Leadbeater's Possum as a case study.

Detailed field and modelling studies have been completed at different spatial scales for the endangered arboreal marsupial, Leadbeater's Possum (Gymnobelideus leadbeateri); a species virtually confined to the ash-type eucalypt forests in the Central Highlands of Victoria, south-eastern Australia. These forests are also subject to considerable pressure to produce timber and paper products. The studies of Leadbeater's Possum highlighted the factors influencing the distribution and abundance of the species ranging from broad distribution patterns, the occupancy of habitat patches at the landscape scale, and the use of individual den sites and the quality of trees that provide food within particular stands. These scales correspond to the entire known range of the species, sub-populations within a metapopulation occupying an ensemble of patches at the landscape scale, and colonies occupying den trees in individual stands. Information on the factors influencing the distribution of Leadbeater's Possum at one spatial scale were found to be important for informing processes at another. For example, an understanding of the species‘ habitat requirements informed the spatial distribution of habitat patches at the landscape level which, in turn, gave insights into predicted metapopulation dynamics. Each spatial scale of ecological investigation of Leadbeater's Possum had a corresponding scale of forest management, and they included: virtually the entire ash-type eucalypt resource in the region, the location of large reserves, the design of corridors and retained patches within production forest landscapes, silvicultural practices employed in individual stands, and the retention of individual trees and clusters of trees on logged sites. This range of forest management scales, and the corresponding-scaled array of ecological studies, have particular implications for the conservation of Leadbeater's Possum. The results of investigations to date have revealed that conservation efforts must focus on ash-type eucalypt forests in the Central Highlands of Victoria because populations of Leadbeater's Possum are virtually confined to these areas. Within the broadscale limits of the distribution of the species, the long-term conservation of Leadbeater's Possum will not only be dependent on large reserves, but also intermediate-scale reserves and corridors within wood production areas, as well changed silvicultural practices to better provide suitable habitat on logged sites. While each strategy will make a contribution to the persistence of Leadbeater's Possum, it also has important limitations; an outcome which highlights the need for a multi-scale approach to attempts to conserve the species. Notably, the overaching implications for the design of an array of different conservation strategies for Leadbeater's Possum could not have been derived from any single study at a particular spatial scale. Thus, the case study on Leadbeater's Possum suggests that consideration of factors at a range of scales should be an integral part of management and conservation planning, not only for this species, but for wildlife per se.

Spatially-correlated extinction in a metapopulation model of Leadbeater's Possum

The importance of considering spatially-correlated extinction in metapopulation viability analyses was investigated using a model of the population dynamics of Gymnobelideus leadbeateri McCoy (Leadbeater's Possum). Fire caused local extinction of G. leadbeateri and induced changes in the suitability of the habitat over a period of decades and centuries. Spatially-correlated fires, in which the correlation between the incidence of fire declines with distance, and uniformly-correlated fires were simulated. The predicted risk of metapopulation extinction increased: (i) as the variance in the number of fires each year increased, (ii) as the mean fire interval decreased, and (iii) as the mean dispersal distance decreased. Incorporating spatial correlation in the incidence of fires between patches had little effect on the results, provided the variance in the number of fires per year remained the same and fires modified habitat quality. The predicted risk of metapopulation extinction was greater for spatially-correlated fires than for uniformly-correlated fires when fires only caused local extinction but did not change habitat suitability. Incorporating spatial correlation in the incidence of fire within patches, which allowed partial burning of patches, reduced the predicted risk of extinction. This effect was only slight when patches were smaller than about 50 ha. The results of our simulations demonstrate the importance of considering correlations in disturbance regimes in metapopulation models, especially if these models are used to assist the design of nature reserves.

The conservation of arboreal marsupials in the montane ash forests of the central highlands of Victoria, south-eastern Australia. VIII. Landscape analysis of the occurrence of arboreal marsupials

We describe the results of landscape analysis of the occurrence of a suite of species of arboreal marsupials in the montane ash forests of the central highlands of Victoria, south-eastern Australia. The species targeted for study were: Yellow-bellied Glider ( Petaurus australis), Mountain Brushtail Possum ( Trichosurus caninus), Greater Glider ( Petauroides volans) and Leadbeater's Possum ( Gymnobelideus leadbeateri). Our analyses involved exploring statistical relationships between the presence/absence of these four species and compositional variables used to characterise the landscape within 20 and 80 ha circles surrounding each of 166, 3 ha, sites surveyed for arboreal marsupials. Many potential statistical models were examined for each of the four species targeted for analysis. With the exception of P. australis, the final model chosen was the null model; i.e. none of the landscape variables were statistically significant as predictors of the presence of animals at a site. In the case of P. australis, three measures of the landscape within the 80 ha circles surrounding our survey sites were found to be statistically significant: (1) the presence of old forest, (2) the steepness of the forest terrain, and, (3) the area of forest on different aspects. There was a significantly higher probability of detecting the species on northerly and westerly aspects, on either steep or flat terrain, and within circles supporting old growth montane ash forest. P. australis has a home range of 40–60 ha which is at least an order of magnitude larger than the other species of arboreal marsupials examined. Thus, the size of the 80 ha circle used to capture data on landscape composition matched the home range size of P. australis more closely than other species of arboreal marsupials examined in this study. This may, in part, explain why it was the only species for which landscape composition variables were found to be significant predictors of occurrence. Our findings tentatively suggest that changes in the spatial coverage of old growth forest that have resulted from past wildfires, post-fire salvage logging and more recent intensive and extensive clearfell logging operations, have created landscape patterns unsuitable for P. australis. The implications of our results for the conservation of the species are discussed. In addition, some difficulties were experienced in the use of landscape-scale data in our statistical analyses, such as identifying attributes of landscape composition that are biologically relevant to the taxa targeted for analysis. We briefly discuss the nature of these problems.

Patterns of co‐occurrence among arboreal marsupials in the forests of central Victoria, southeastern Australia

Abstract Patterns of co‐occurrence were examined among the suite of species of arboreal marsupials that inhabit the montane ash forests of the Central Highlands of Victoria, southeastern Australia. The data used in our analyses were counts of different species of arboreal marsupials derived from stagwatching surveys of 152 sites throughout the Central Highlands region. Our work investigated both the number of species that tend to occur together, as well as identity of the taxa in such associations. A total of eight different species of arboreal marsupials were recorded from field surveys of montane ash forests: Leadbeater's Possum (Gymnobelideus leadbeateri), Sugar Glider (Petaurus breviceps), Yellow‐bellied Glider (Petaurus australis), Greater Glider (Petauroides volans), Mountain Brushtail Possum (Trichosurus caninus), Feathertail Glider (Acrobates pygmaeus), Common Ringtail Possum (Pseudocheirusperegrinus), and Eastern Pygmy Possum (Cercartetus nanus). Large assemblages of taxa were rare and no sites supported the full array of species of arboreal marsupials– the maximum number of species recorded on a given 3 ha site was five. The results of our analyses indicated that if any one species of arboreal marsupials was present at a site, then on average 1. 5 other taxa will co‐inhabit that site. The exception was the Common Ringtail Possum. When this species was detected, few other arboreal marsupial taxa tended to be recorded with it. Principal Co‐ordinates Analysis showed that although combinations of animals comprised of either Mountain Brushtail Possum, Leadbeater's Possum, or Greater Glider were often recorded, there were no strong patterns in the identities of co‐occurring taxa. This finding, together with the result that most taxa in these forests typically co‐occurred with one or two other species, indicates that none of the arboreal marsupials inhabiting the montane ash forests of the Central Highlands of Victoria would be a good surrogate for (or ‘indicator’ of), the presence of the suite of other species in the assemblage.

Scale Insects under Eucalypt Bark: a Revision of the Australian Genus Phacelococcus Miller (Hemiptera: Coccoidea: Eriococcidae)

The scale insect genus Phacelococcus Miller originally was created for a single species, Phacelococcus brookesae Miller, found under the bark of Eucalyptus globulus Labill. (Myrtaceae) in Tasmania. Three new species, all from under the bark of Eucalyptus species in mainland Australia, share the characteristics of Phacelococcus: clusters of quinquelocular pores, absence of enlarged dorsal setae and reduced anal lobes. P. brookesae is redescribed and the generic diagnosis of Phacelococcus is expanded to include the three species, P. cookae sp.n., P. frenchi sp.n. and P. subcorticalis sp.n., which are described and illustrated. the latter two species are sometimes so abundant on the trunks of their host trees that they are fed upon by yellow‐bellied gliders and probably Leadbeater's possums (Mammalia: Marsupialia: Petauridae).

Modelling the abundance of rare species: statistical models for counts with extra zeros

We consider several statistical models for the analysis of the abundance of a rare species and these are illustrated in detail with data for the abundance of Leadbeater's Possum in montane ash forests of south-eastern Australia. These data are characterised by a discrete distribution with the zero class inflated. In many statistical problems the parameters of this distribution depend on covariates, such as the number of hollow bearing trees. We advocate a conditional model which is simple to interpret and readily fitted. We show how to obtain standard errors for the parameter estimates. We also show how to estimate the mean abundance of animals at a site. The methods outlined in this paper offer a powerful framework for the study of problems having a discrete response (like abundance) with the zero class inflated.