Ana Gracanin

Understanding the gliding ability of gliding mammals provides important insights into their evolutionary adaptations as well as critical information to guide habitat management and conservation planning, especially to mitigate barriers caused by habitat fragmentation. We studied the gliding movements of the endangered southern greater glider (Petauroides volans), a nocturnal marsupial reliant on mature forests, in five locations in NSW, Australia. Gliding angles were measured from 41 glides using three methods: (i) observing glides from captured gliders released onto isolated trees; (ii) observing glides after individuals left their den hollows in isolated hollow-bearing trees after sunset and (iii) recording glides while observers were engaged in spotlighting or other fieldwork. Trees in our study areas ranged from 16 to 40 m tall. Greater gliders launched from an average height of 21.8 m above ground and landed at an average height of 4.7 m, achieving an average horizontal glide distance of 19.1 m (range: 6.7–49.6 m). The average glide ratio (horizontal distance/height dropped) was 1:1.1 with an average glide angle of 43.5°. These estimates of glide performance may vary in other forests with different structural attributes, particularly taller canopies. The results of this study can be incorporated into management strategies to help maintain habitat connectivity and mitigate the effects of habitat fragmentation so as to support the conservation of this endangered species.

Context: Southern greater gliders (Petauroides volans) are obligate hollow users. Few studies have reported on nest box use by greater gliders, resulting in designs that often lack robust experimental testing, and concerns remain about thermal suitability. Aims: This study evaluated the effectiveness of nest boxes as supplementary habitat for southern greater gliders. Methods: Nest boxes were installed in areas with varying abundance of greater gliders and monitored over 2 years. Greater glider activity patterns and nest box thermal properties were compared with 16 tree hollows. Key results: Of the 34 nest boxes installed, 11 (31%) were used by southern greater gliders. Nest boxes placed in areas with a lower abundance of southern greater gliders and with fewer natural tree hollows, had a higher likelihood of use by southern greater gliders. European honeybees (Apis mellifera) were observed to impact nest box use by greater gliders. Nest boxes provided less thermal insulation than tree hollows, although both den types experienced internal temperatures above 30°C while occupied by southern greater gliders. None of the environmental co-variates tested had a significant influence on whether a southern greater glider would leave a nest box and not return. Conclusions: This study found that nest boxes can provide supplementary habitat for greater gliders, particularly in areas lacking natural tree hollows. There was no difference in activity patterns and use between nest boxes and tree hollows. Implications: Strategic placement of nest boxes may support short-term conservation management of southern greater gliders by improving habitat availability.

The loss of hollow‐bearing trees poses a critical threat to hollow‐dependent species. Nest boxes as supplementary habitat have emerged as a conservation tool for certain species, but their use in providing habitat for Southern Greater Gliders (Petauroides volans), a heat‐sensitive and hollow‐dependent species, remains limited. This study investigates the uptake and use of nest boxes designed specifically for Greater Gliders in a postfire environment. Thirty nest boxes were installed at a site that experienced moderate to severe fire during the 2019/2020 bushfires. Four different nest box designs were investigated for their thermal properties, colonisation rates and usage patterns. The time for a nest box to be used by a Greater Glider was rapid, at an average of 34 days after time of installation. Continuous camera monitoring over the course of a year revealed 100% colonisation, with gliders consistently using nest boxes across seasons regardless of nest box design. We found that nest box design influenced internal temperatures, and the best performing nest box design (constructed of wood and without foil insulation) was on average 1.99°C cooler inside than ambient temperatures (on warm days equal to or above 20°C). In comparison, natural tree hollows in use by Greater Gliders at the study site, had a much greater thermal buffer (on average 7.32°C cooler than ambient temperatures on warm days). Observations of Greater Gliders sitting outside at the entrance hole of nest boxes during the day was linked to warmer temperatures, indicating Greater Gliders likely exited nest boxes to thermoregulate. This study identified a rapid acceptance of nest boxes by the Greater Glider and offered insights into the role of nest boxes as supplementary habitat to assist population recovery following the loss of hollow‐bearing trees.

Camera traps are widely used in wildlife research and monitoring, so it is imperative to understand their strengths, limitations, and potential for increasing impact. We investigated a decade of use of wildlife cameras (2012–2022) with a case study on Australian terrestrial vertebrates using a multifaceted approach. We (i) synthesised information from a literature review; (ii) conducted an online questionnaire of 132 professionals; (iii) hosted an in‐person workshop of 28 leading experts representing academia, non‐governmental organisations (NGOs), and government; and (iv) mapped camera trap usage based on all sources. We predicted that the last decade would have shown: (i) exponentially increasing sampling effort, a continuation of camera usage trends up to 2012; (ii) analytics to have shifted from naive presence/absence and capture rates towards hierarchical modelling that accounts for imperfect detection, thereby improving the quality of outputs and inferences on occupancy, abundance, and density; and (iii) broader research scales in terms of multi‐species, multi‐site and multi‐year studies. However, the results showed that the sampling effort has reached a plateau, with publication rates increasing only modestly. Users reported reaching a saturation point in terms of images that could be processed by humans and time for complex analyses and academic writing. There were strong taxonomic and geographic biases towards medium–large mammals (>500 g) in forests along Australia's southeastern coastlines, reflecting proximity to major cities. Regarding analytical choices, bias‐prone indices still accounted for ~50% of outputs and this was consistent across user groups. Multi‐species, multi‐site and multiple‐year studies were rare, largely driven by hesitancy around collaboration and data sharing. There is no widely used repository for wildlife camera images and the Atlas of Living Australia (ALA) is the dominant repository for sharing tabular occurrence records. However, the ALA is presence‐only and thus is unsuitable for creating detection histories with absences, inhibiting hierarchical modelling. Workshop discussions identified a pressing need for collaboration to enhance the efficiency, quality and scale of research and management outcomes, leading to the proposal of a Wildlife Observatory of Australia (WildObs). To encourage data standards and sharing, WildObs should (i) promote a metadata collection app; (ii) create a tagged image repository to facilitate artificial intelligence/machine learning (AI/ML) computer vision research in this space; (iii) address the image identification bottleneck via the use of AI/ML‐powered image‐processing platforms; (iv) create data commons for detection histories that are suitable for hierarchical modelling; and (v) provide capacity building and tools for hierarchical modelling. Our review highlights that while Australia's investments in monitoring biodiversity with cameras position it to be a global leader in this context, realising that potential requires a paradigm shift towards best practices for collecting, curating, sharing and analysing ‘Big Data’. Our findings and framework have broad applicability outside Australia to enhance camera usage to meet conservation and management objectives ranging from local to global scales. This review articulates a country/continental observatory approach that is also suitable for international collaborative wildlife research networks.

Southern greater gliders (Petauroides volans) are endangered Australian marsupials for which there is little health data currently available. Chlamydia pecorum is the only reported pathogen of greater gliders and infects a broad range of hosts, including other marsupials, ruminants, swine and birds. Conjunctival and cloacal swabs collected from thirty-two southern greater gliders across southeastern New South Wales, Australia were screened for Chlamydia spp. by 23S real-time PCR. None of the ninety-six swabs tested returned a positive result for Chlamydia DNA. We found no evidence of Chlamydia infection among the four geographically disparate populations sampled, suggesting that Chlamydia may not pose a widespread health risk to southern greater gliders in this region, based on the current data. However, various clinical signs of ophthalmic pathology were observed, warranting further investigation to determine their underlying aetiology.

Detection of animals is influenced by species traits, environment, season and the methods used. Analytical techniques can address imperfect detection, such as false absences, but data limitations hinder accurate density estimation. Identifying field survey methods that optimize detectability is therefore a high research priority, especially for species of conservation concern. We consider a model species, the sugar glider Petaurus notatus, to evaluate how optimizing detections can affect survey outcomes. A literature meta‐analysis found little innovation in baiting approaches for sugar gliders over four decades. Honey‐based baits prevailed, despite emerging evidence of opportunistic carnivory. We compared sugar glider detection probabilities using honey and fish‐based baits in a spatially explicit capture‐recapture study. Fish bait increased detections 33‐fold, and density estimation (0.12 ha⁻¹) was only possible using the fish‐baited data – detections were too sparse using honey‐bait to facilitate analysis. Other factors that influence detectability include trap height and habitat connectivity, which were top moderators in our meta‐analysis, but these may be secondary to the bait or lure used. By using (i) species‐specific bait that accounts for the biology of the target species, and (ii) analytical tools to account for imperfect detection and heterogeneous movement of animals, we achieved good enough detection probabilities to undertake detailed analysis of the spatial ecology of sugar gliders. Compared to honey‐based baits (the prevailing approach of other studies on this species), the high detection probability attained with fish‐based baits provides an improvement on conventional practices. Our study is an important reminder that accounting for the biology of the target species during survey effort may mean the difference between collecting enough data for analysis or not. In the context of species conservation, optimizing detection likelihoods is critical for answering ecological questions about cryptic species, and our results demonstrate the need to reappraise generic approaches when better information is available.

Context: In highly fragmented landscapes, arboreal mammals are limited by their ability to move and disperse between core habitats. Connectivity modelling for multiple species allows scientists to identify the most efficient movement and/or dispersal pathway(s) to prioritise for conservation efforts. Objectives: In this study, we evaluated the most cost-effective corridor pathway for eight species of arboreal mammals, with particular emphasis on an endangered population of greater gliders (Petauroides volans). Methods: We use species distribution modelling and circuit theory to calculate connectivity in the landscape for each species. An all-species corridor was then modelled using a least cost path analysis. The final corridor was evaluated for all species through ground-truthing accessible segments. Results: We identified that some segments of the corridor had low suitability for highly specialised species, and those with tree hollow requirements for denning. The all-species corridor also utilised an artificial crossing structure over a highway, and monitoring of this rope bridge found only two species (sugar gliders; Petaurus breviceps and ringtail possums; Pseudocheirus peregrinus) used the structure on occasion. Thus, the modelled corridor pathway was not suitable for all species, rather it was found to be more suitable for generalist species such as sugar gliders, ringtail possums, brown antechinus; Antechinus stuartii and brushtail possums; Trichosurus vulpecula. Conclusions: Our study exemplifies the importance of ground-truthing in connectivity conservation studies to ensure conservation outcomes are realised. Furthermore, we provide detailed recommendations for relevant conservation managers, to improve the usage of these existing habitat corridors by arboreal species.

Habitat loss and fragmentation contribute significantly to the decline of arboreal mammal populations. As populations become fragmented and isolated, a reduction in gene flow can result in a loss of genetic diversity and have an overall impact upon long-term persistence. Creating wildlife corridors can mitigate such effects by increasing the movement and dispersal of animals, thus acting to reduce population isolation. To evaluate the success of a corridor, a before–after experimental research framework can be used. Here, we report the genetic diversity and structure of sugar glider (Petaurus breviceps) sampling locations within a fragmented landscape prior to the implementation of a wildlife corridor. This study used 5999 genome-wide SNPs from 94 sugar gliders caught from 8 locations in a fragmented landscape in south-eastern New South Wales, Australia. Overall genetic structure was limited, and gene flow was detected across the landscape. Our findings indicate that the study area contains one large population. A major highway dissecting the landscape did not act as a significant barrier to dispersal, though this may be because of its relatively new presence in the landscape (completed in 2018). Future studies may yet indicate its long-term impact as a barrier to gene flow. Future work should aim to repeat the methods of this study to examine the medium-to-long-term impacts of the wildlife corridor on sugar gliders, as well as examine the genetic structure of other native, specialist species in the landscape.

Hollow-bearing trees provide essential habitat for a range of threatened Australian wildlife species. Limited data exist for the hollow choice of greater gliders (Petauroides volans). This study aimed to provide the first comprehensive overview of the dimensions and characteristics of the den trees and hollows used by greater gliders, in the context of an endangered population. Through spotlighting and stag-watching, we identified 68 greater glider hollows in 54 den trees. When compared to reference hollows, greater gliders appeared to be preferentially choosing dens based on tree species, tree diameter at breast height (DBH), hollow type, hollow height and hollow depth. The aspect, entrance diameter, and cavity wall thickness of hollows did not appear to be influencing den choice, when compared to reference hollows. Greater gliders preferred to den in blackbutt (Eucalyptus pilularis) trees with a mean DBH of 114.1 cm (±4.3 cm). Hollows were most commonly a ‘branch end’ type of hollow. Mean depth of hollows was 252 cm (±12 cm). Mean hollow height was 15.4 m (±0.4 m). While not significant, hollows had a mean minimum hollow entrance of 18.1 cm (±0.6 cm) and a mean maximum cavity wall thickness of 8.0 cm (±0.7 cm). It is likely that hollow depth contributes to temperature buffering within dens, which is important for den choice as greater gliders are highly sensitive to hot temperatures. Our findings have important conservation implications for assessing den trees, and for improving designs of nest boxes and artificial cavities. Hollow-bearing trees provide essential habitat for a range of threatened Australian wildlife species. Limited data exist for the hollow choice of greater gliders (Petauroides volans). This study aimed to provide the first comprehensive overview of the dimensions and characteristics of the den trees and hollows used by greater gliders, in the context of an endangered population. Through spotlighting and stag-watching, we identified 68 greater glider hollows in 54 den trees. When compared to reference hollows, greater gliders appeared to be preferentially choosing dens based on tree species, tree diameter at breast height (DBH), hollow type, hollow height and hollow depth. The aspect, entrance diameter, and cavity wall thickness of hollows did not appear to be influencing den choice, when compared to reference hollows. Greater gliders preferred to den in blackbutt (Eucalyptus pilularis) trees with a mean DBH of 114.1 cm (±4.3 cm). Hollows were most commonly a ‘branch end’ type of hollow. Mean depth of hollows was 252 cm (±12 cm). Mean hollow height was 15.4 m (±0.4 m). While not significant, hollows had a mean minimum hollow entrance of 18.1 cm (±0.6 cm) and a mean maximum cavity wall thickness of 8.0 cm (±0.7 cm). It is likely that hollow depth contributes to temperature buffering within dens, which is important for den choice as greater gliders are highly sensitive to hot temperatures. Our findings have important conservation implications for assessing den trees, and for improving designs of nest boxes and artificial cavities.

Camera trapping to study wildlife allows for data collection, without the need to capture animals. Traditionally, camera traps have been used to target larger terrestrial mammal species, though recently novel methods and adjustments in procedures have meant camera traps can be used to study small mammals. The selfie trap (a camera trapping method) may present robust sampling and ecological study of small mammals. This study aimed to evaluate the selfie trap method in terms of its ability to detect species and estimate population density. To address this aim, standard small mammal live trapping was undertaken, immediately followed by camera trapping using the selfie trap. Both methods were set to target the arboreal sugar glider (Petaurus breviceps) and semi-arboreal brown antechinus (Antechinus stuartii). The more ground-dwelling bush rat (Rattus fuscipes) was also live trapped and recorded on camera. Across four survey areas, the probability of detection for each of the three species was higher for selfie traps than for live trapping. Spatially explicit capture-recapture models showed that selfie traps were superior at estimating density for brown antechinus and sugar gliders, when compared to simulated live trapping data. Hit rates (number of videos per various time intervals) were correlated with abundance. When correlating various hit rate intervals with abundance, the use of 10-min hit rate was best for predicting sugar glider abundance (R² = 0.94). The abundance of brown antechinus was estimated from selfie traps using a 24-h hit rate as a predictor (R² = 0.85). For sugar gliders, the selfie trap can replace live trapping as individuals can be identified through their unique facial stripes and natural ear scars, and thus used in capture-recapture analysis. This method may be useful for monitoring the abundance of other small mammal species that can also be individually recognized from photographs.