Genome-wide SNPs Detect Fine-scale Genetic Structure in Threatened Populations of Squirrel Glider Petaurus Norfolcensis

Australian arboreal mammals are experiencing significant population declines, particularly due to land clearing and resulting habitat fragmentation. The squirrel glider, Petaurus norfolcensis, is a threatened species in New South Wales, with a stronghold population in the Lake Macquarie Local Government Area (LGA) where fragmentation due to urbanization is an ongoing problem for the species conservation. Here we report on the use of squirrel glider mitochondrial (385 bp cytochrome b gene, 70 individuals) and nuclear DNA (6,812 SNPs, 87 individuals) markers to assess their population genetic structure and connectivity across 14 locations sampled in the Lake Macquarie LGA. The mitochondrial DNA sequences detected evidence of a historical genetic bottleneck, while the genome-wide SNPs detected significant population structure in the Lake Macquarie squirrel glider populations at scales as fine as one kilometer. There was no evidence of inbreeding within patches, however there were clear effects of habitat fragmentation and biogeographical barriers on gene flow. A least cost path analysis identified thin linear corridors that have high priority for conservation. These areas should be protected to avoid further isolation of squirrel glider populations and the loss of genetic diversity through genetic drift.

Wildlife of the Box-Ironbark Country

Victoria's Box–Ironbark region is one of the most important areas of animal diversity and significance in southern Australia. The forests and woodlands of this region provide critical habitat for a diverse array of woodland-dependent animals, including many threatened and declining species such as the Squirrel Glider, Brush-tailed Phascogale, Regent Honeyeater, Swift Parrot, Pink-tailed Worm-Lizard, Woodland Blind Snake, Tree Goanna and Bibron's Toadlet. Wildlife of the Box–Ironbark Country gives a comprehensive overview of the ecology of the Box–Ironbark habitats and their wildlife, and how climate change is having a major influence. This extensively revised second edition covers all of the mammals, birds, reptiles and frogs that occur in the region, with a brief description of their distribution, status, ecology and identification, together with a detailed distribution map and superb colour photograph for each species. The book includes a 'Where to watch' section, featuring a selection of national parks, state parks and nature conservation reserves where people can experience the ecosystem and its wildlife for themselves. This book is intended for land managers, conservation and wildlife workers, fauna consultants, landholders, teachers, students, naturalists and all those interested in learning about and appreciating the wildlife of this fascinating and endangered ecosystem.

Use of tall wooden poles by four species of gliding mammal provides further proof of concept for habitat restoration

Tall wooden poles (glide poles) and rope canopy-bridges are frequently installed along new highways in Australia to maintain population connectivity for gliding mammals. Knowledge of the use of these structures is rudimentary. We monitored two pairs of glide poles and a canopy-bridge over three years at Port Macquarie, New South Wales. The sugar glider (Petaurus breviceps) and the squirrel glider (Petaurus norfolcensis) were collectively detected on 12–18% of nights on the pole pairs compared with 1% on the rope-bridge. The feathertail glider (Acrobates frontalis) was detected on 3% of nights on the pole pairs compared with 0.2% on the rope-bridge. The yellow-bellied glider (Petaurus australis) was detected twice on one pole. Our results demonstrate that gliding mammals readily use glide poles. Further research is needed to resolve whether glide poles can mitigate the barrier effect of the road canopy gap.

Time budget of the squirrel glider (Petaurus norfolcensis) in subtropical Australia

Exudivorous mammals exploit food items of high quality and high rates of renewal, offset by wide dispersion and variable availability. How this influences foraging effort and size-related foraging efficiency remains poorly described. We examined the time budget of 5–6 male and 5–6 female squirrel gliders (Petaurus norfolcensis) during 6–8 nights in each of three seasons that were stratified by moon phase. Radio-collared gliders were observed during a series of 1-h focal observations from dusk until dawn. Feeding dominated the time budget, accounting for 78% of observation time, or 85% of time when combined with behaviours associated with foraging. Females appear to maximise feeding rates before entering the energetically demanding phase of late lactation. Little time was spent resting while outside the den. Longer nights and the full moon were associated with later emergence and earlier retirement times. Animals re-entered their tree-hollow dens during the night, representing 2% of activity in late spring, 18% in winter and 9% in autumn (10% overall). This behaviour may relate to predation risk and lactation demands. We reviewed the percentage of the time budget that petaurid gliders devoted to feeding and found no clear relationship with body size.

Population monitoring of an urban gliding mammal in eastern Australia

Long-term monitoring is an important element of species conservation. This study describes changes in the size of a squirrel glider (Petaurus norfolcensis) population over a 10-year period. The population occupied a 45-ha forest remnant within the urban area of Brisbane. Gliders were tagged from 25 nights of trapping during 2006–08 and from 16 nights of trapping in 2015. Population modelling was used to estimate adult population size. This suggested the adult population comprised 30–40 individuals at the beginning and end of the 10-year period. It reached a peak of 70 individuals in mid-2007. These data suggest that the study area contains a small population that is prone to interannual variation but there was no evidence of it being in decline. Survival estimates during 2006–08 were equivalent to those estimated for a larger population in Victoria. Population monitoring should be continued to determine how resilient this population is to population decline and to investigate factors that may cause decline. This study provides an example of an approach that could be used to monitor threatened populations of the squirrel glider.

Demographic parameters of the squirrel glider (Petaurus norfolcensis) in an urban forest remnant

The effective management of species requires detailed knowledge of key population parameters. A capture–mark–recapture study of the squirrel glider (Petaurus norfolcensis) was conducted in an urban forest remnant in Brisbane, south-east Queensland. A total of 187 adult gliders (96 females, 91 males) was captured 620 times, in 19 sessions over a 4-year period. A Cormack–Jolly–Seber model was employed to estimate adult survival and abundance. Factors that may affect survival (e.g. sex, year, season) were included in population models. The overall probability of annual apparent survival was 0.49 ± 0.08. The capture probability over the duration of the study was 0.38 ± 0.03. The size of the local population was highest in the first year of the study (70–113 individuals) but then declined and generally remained low in the last two years. Apparent survival may include an unknown component of dispersal. However, our study area was mostly surrounded by a hostile urban matrix, so the effect of dispersal may have been minimal. Further studies that assess the survival of squirrel gliders are needed to assess the extent to which this parameter varies among localities.

Radio-collared squirrel glider (Petaurus norfolcensis) struck by vehicle and transported 500 km along freeway

Roadkill (the mortality of animals through wildlife–vehicle collisions) is one of the main impacts of roads on wildlife. Studies quantifying the location and rate of roadkill to identify ‘hot spots’ are often used to guide the location of mitigation efforts, such as fencing or wildlife crossing structures. However, sometimes quantifying rates of roadkill can be challenging, particularly for species that are small and difficult to detect. In our study, a squirrel glider that was trapped and radio-collared in north-east Victoria was found as roadkill more than 500 km away, suggesting that a vehicle struck the animal and carried the carcass away from the site of impact. Our observation is the first evidence that this occurs for squirrel gliders.

The influence of urban encroachment on squirrel gliders (Petaurus norfolcensis): effects of road density, light and noise pollution

Context Loss and degradation of habitat from urban development is a key threat to the squirrel glider (Petaurus norfolcensis), because its distribution coincides where most people live in Australia. Squirrel gliders are known to occur in or around urban fringes where native vegetation is retained; however, little is known about specific anthropogenic factors that may affect their persistence. Aims We investigated the relative influence of biophysical and urban factors on the use of large hollow-bearing Eucalyptus trees, which are a key resource for squirrel gliders. The study was located in a typical urban growth area located in southern New South Wales. Methods A stratified random sampling approach was used to survey squirrel gliders in urban and rural areas. Infrared, motion-sensor cameras were placed in 34 selected trees for 17 nights to record squirrel glider occupancy and activity. Data on urban (e.g. light and noise pollution levels, road and housing density) and biophysical (e.g. tree height, hollow-bearing tree density, vegetation cover) variables were recorded at each survey tree. Data were statistically analysed using general linear modelling approaches. Key results Squirrel gliders were detected more frequently in the rural matrix (23.4% of camera trap-nights) than in urban areas (9.5%). Model results showed that tree height, and the distance to neighbouring trees, had a significant influence on the occurrence and activity of squirrel gliders. Road density and light pollution were included in ‘best’ models to explain glider activity (a negative influence), and noise pollution negatively influenced glider occurrence. Although gliders used large trees in both urban and rural areas, activity generally decreased as levels of urbanisation increased. Conclusions and implications Access to and availability of key resources such as tall, hollow-bearing trees is critical for gliders to persist in urban environments. Squirrel gliders will tolerate human stressors such as roads, noise and light pollution to a certain extent, but impacts on population viability remain largely unknown. Novel solutions need to be developed to lessen the effects of anthropogenic factors (such as light and noise) on patches of native vegetation retained in urban areas for conservation purposes.