Comparison of home range size, habitat use and the influence of resource variations between two species of greater gliders (Petauroides minor and Petauroides volans)

Knowledge of the spatial requirements of a species is fundamental to understanding its environmental requirements. However, this can be challenging as the size of a species' home range can be influenced by ecological factors such as diet and size-dependent metabolic demands, as well as factors related to the quality of their habitat such as the density and distribution of resources needed for food and shelter. Until recently, the genus Petauroides was thought to include only a single species with a widespread distribution across eastern Australia. However, a recent study has provided genetic and morphological evidence supporting Petauroides minor as a distinct northern species. Previous studies have focused on the ecology of P. volans, but there has been inadequate research on P. minor. Data on home range and habitat use were obtained for both species using a combination of techniques including GPS collar locations, radiotelemetry, and spotlighting and comparisons were made using consistent methodology. Home range sizes of P. minor (4.79 ha ± 0.97 s.d., KUD .95) were significantly larger than those of P. volans (2.0 ha ± 0.42 s.d., KUD .95). There were no significant differences between male and female home range sizes in either species. Both species showed site-specific preferences for tree species and for larger diameter trees for both forage and shelter. Tree size and biomass/ha were significantly greater in the P. volans study sites than the P. minor study sites and there was a negative correlation between home range size and eucalypt biomass. Larger home range size is likely driven by the substantial differences in biomass between northern (tropical) and southern (temperate) eucalypt-dominated habitats affecting the quality and quantity of resources for food and shelter. Understanding landscape use and habitat requirements within each species of Petauroides can provide important information regarding limiting factors and in directing conservation and management planning.

Conservation genomics of an endangered arboreal mammal following the 2019-2020 Australian megafire

The impacts of a changing climate threaten species, populations and ecosystems. Despite these significant and large-scale impacts on threatened species, many remain understudied and have little to no genetic information available. The greater glider, Petauroides volans, is an endangered species highly sensitive to the predicted changes in temperature under a changing climate and was recently severely impacted by a megafire natural disaster (85% estimated population loss). Baseline genetic data is essential for conservation management and for detecting detrimental changes in fire-effected populations. We collected genetic samples within 2 years post the 2019-2020 catastrophic Australian bushfires to examine adaptive potential, baseline genetic diversity and population structure, across their southern range in the state of New South Wales. Population genomic analyses were conducted using 8493 genome-wide SNPs for 86 greater glider individuals across 14 geographic locations. Substantial genetic structure was detected across locations, with low genetic diversity and effective population sizes observed in isolated areas. Additionally, we found signals of putative adaptation in response to temperature in greater gliders using a genotype-environment association analysis. These findings have important implications for the management of greater glider populations by identifying at-risk populations and identifying adaptive potential. We demonstrate the importance of baseline genetic information for endangered species as a practical approach to conservation. This is particularly important given the threat that changes in temperatures and megafire events, as predicted under a changing climate, poses for this species.

Multiyear monitoring of threatened iconic arboreal mammals in a mid‐elevation conservation reserve in eastern Australia

Multiyear investigations of population dynamics are fundamental to threatened species conservation. We used multiseason occupancy based on spotlight surveys to investigate dynamic occupancy of the koala and the greater glider over an 8‐year period that encompassed a severe drought in year 6. We combined our occupancy estimates with literature estimates of density to estimate the population sizes of these species within the focal conservation reserve. Both species showed substantial yearly variation in the probability of detection (koala: 0.13–0.24; greater glider: 0.12–0.36). Detection of the koala did not follow any obvious pattern. Low detection of the greater glider coincided with the drought and two subsequent years. We suggest the low detection reflected a decline in abundance. The probability of occupancy of the koala was estimated to be 0.88 (95% CI: 0.75–1.0) in year 8. Autonomous recording units were also used in year 8, enabling an independent occupancy estimate of 0.80 (0.64–0.90). We found no evidence of a drought‐induced decline in the koala. Habitat variables had a weak influence on koala occupancy probabilities. The probability of occupancy of the greater glider changed little over time, from 0.52 (95% CI: 0.24–0.81) to 0.63 (0.42–0.85) in year 8. Modeling suggested that the probability of colonization was positively influenced by the percentage cover of rainforest. Increased cover of these nonbrowse trees may reflect thermal buffering, site productivity, or soil moisture. We estimate that our study reserve is likely to contain >900 adult koalas and >2400 adult greater gliders. These are among some of the first reserve‐wide estimates for these species. Our study reserve can play an important role in the conservation of both species.

Elevation, disturbance, and forest type drive the occurrence of a specialist arboreal folivore

Quantifying the factors associated with the presence and abundance of species is critical for conservation. Here, we quantify the factors associated with the occurrence of the Southern Greater Glider in the forests of the Central Highlands of Victoria, south-eastern Australia. We gathered counts of animals along transects and constructed models of the probability of absence, and then the abundance if animals were present (conditional abundance), based on species' associations with forest type, forest age, the abundance of denning sites in large old hollow-bearing trees, climatic conditions, and vegetation density. We found evidence of forest type effects, with animals being extremely uncommon in Alpine Ash and Shining Gum forest. In Mountain Ash forest, we found a negative relationship between the abundance of hollow-bearing trees and the probability of Southern Greater Glider absence. We also found a forest age effect, with the Southern Greater Glider completely absent from the youngest sites that were subject to a high-severity, stand-replacing wildfire in 2009. The best fitting conditional abundance model for the Southern Greater Glider included a strong positive effect of elevation; the species was more abundant in Mountain Ash forests at higher elevations. Our study highlights the importance of sites with large old hollow-bearing trees for the Southern Greater Glider, although such trees are in rapid decline in Mountain Ash forests. The influence of elevation on conditional abundance suggests that areas at higher elevations will be increasingly important for the conservation of the species, except where Mountain Ash forest is replaced by different tree species that may be unsuitable for the Southern Greater Glider.

Koala tree selection in a mixed-tenure landscape and post-fire implications

Abstract ContextThe more frequent and intense bushfires predicted under climate change are likely to heavily impact koalas living inside protected areas and intact forests, which makes koala habitat in asset protection zones more important. Understanding how koalas use different habitats in a mixed-tenure landscape can inform effective conservation management. AimsThe aims of this study were to determine (1) the species and size of trees used by koalas, (2) whether choice of daytime trees was affected by available proportions of tree species and sizes in koala home ranges, and (3) whether developed land was used as frequently as native forest. MethodsTree use by koalas was determined by radio-tracking 10 koalas for an average of 12 months and recording the species and diameter of trees they occupied. To compare the proportions of tree species used by koalas with those available, tree availability was measured using random quadrats in the home ranges of five koalas that used forested areas extensively. The habitats used by 10 koalas were classified as native forest or developed land to investigate the importance of human-modified areas. Key resultsEucalyptus punctata was a preferred tree species, but each individual used four to nine species. Tree species were not chosen solely on the basis of available proportions; some species were selected preferentially. Half of the koalas used more developed land than native forest. Koalas preferentially used trees with larger diameters than the mean of available trees, and selected larger trees in developed areas than in native forest and when re-using trees. ConclusionsDespite the higher availability of trees in protected native forest at the site, 70% of the koalas used developed land in and around asset protection zones. Koalas whose home ranges were geographically close, but had different soil types and vegetation communities, were able to utilise different tree species. ImplicationsKoalas would benefit from protection of remnant native forests containing preferred trees on shale cap soil and conservation of native vegetation corridors along fence lines and in paddocks in developed areas because they are valuable resources and connect patchy landscapes. Protecting koalas on developed land improves their likelihood of surviving bushfires, allowing recolonisation of surrounding protected areas.

Genetic evidence supports three previously described species of greater glider, Petauroides volans, P. minor, and P. armillatus

The identification and classification of species are essential for effective conservation management. This year, Australia experienced a bushfire season of unprecedented severity, resulting in widespread habitat loss and mortality. As a result, there has been an increased focus on understanding genetic diversity and structure across the range of individual species to protect resilience in the face of climate change. The greater glider (Petauroides volans) is a large, gliding eucalypt folivore. This nocturnal arboreal marsupial has a wide distribution across eastern Australia and is considered the sole extant member of the genus Petauroides. Differences in morphology have led to suggestions that the one accepted species is actually three. This would have substantial impacts on conservation management, particularly given a recent history of declining populations, coupled with extensive wildfires. Until now, genetic evidence to support multiple species has been lacking. For the first time, we used DArT sequencing on greater glider tissue samples from multiple regions and found evidence of three operational taxonomic units (OTUs) representing northern, central and southern groups. The three OTUs were also supported by our morphological data. These findings have important implications for greater glider management and highlight the role of genetics in helping to assess conservation status.