Thesis
Small population ecology: the squirrel glider (Petaurus norfolcensis) as a model species for conserving arboreal mammals in urban managed habitat
Southern Cross University
Doctor of Philosophy (PhD), Southern Cross University
2024
DOI:
https://doi.org/10.25918/thesis.532
Appears in Recent Southern Cross PhD Theses
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Abstract
In urban landscapes, native mammals often occur as small, disjunct populations which are vulnerable to extinction. However, they can provide useful models for understanding extinction processes. This thesis focusses on the squirrel glider (Petaurus norfolcensis), a small gliding mammal representative of Australian arboreal species threatened by habitat loss. The species relies on resources found primarily in mature native forest. In the urban forest remnants of eastern Australia, the species is threatened by fragmentation and isolation, barriers to movement, loss of tree hollows, increased predation, and erosion of genetic diversity.
Two squirrel glider populations occupying forest fragments in Brisbane, Australia were studied over 16 years. One occupied an isolated urban remnant, and the other a larger, interconnected peri-urban forest. The urban population has been in decline steadily since 2009, while the peri-urban population has remained stable with some inter-year variation. Survival was higher in the peri-urban gliders than the urban gliders (0.70±0.14 versus 0.32±0.04). It was hypothesised that the urban population would show inbreeding depression due to isolation. However, the urban gliders did not show evidence of inbreeding depression, and observed heterozygosity differed little between the two populations (0.261±0.004 urban, 0.262±0.003 peri-urban). This study could not determine whether genetic diversity influenced survival at the urban site, and further data such as offspring mortality may be required.
Other potential drivers of decline were explored, including rainfall and predation. Rainfall, which varied greatly over the study period may influence food availability, as nectar from flowering trees forms a major part of the glider’s diet. Low floral output during droughts may reduce breeding success. Breeding appeared related to rainfall between 2015–2021 at the urban site, with a marked drop during the 2019 drought (39% of females bred), followed by a rebound in 2020 (89% of females bred). No direct evidence of predation was found, though red foxes (Vulpes vulpes) were abundant at the urban site and powerful owls (Ninox strenua) were recently recorded nearby. Fur cortisol, as a predictor of individual and population-level stress, was also tested. No differences were found between habitat locations, but differences occurred between sites and years, possibly linked to drought and the 2019 bushfire.
Protecting small populations is useful for species conservation at the regional level. This study should provide insights for conserving related species such as the mahogany glider (P. gracilis) and Leadbeater’s possum (Gymnobelideus leadbeateri), that are threatened by habitat loss and fragmentation.
Details
- Title
- Small population ecology: the squirrel glider (Petaurus norfolcensis) as a model species for conserving arboreal mammals in urban managed habitat
- Creators
- Anita Jane Marks
- Contributors
- Ross Goldingay (Supervisor) - Southern Cross UniversityDavid A Newell (Supervisor) - Southern Cross University
- Awarding Institution
- Southern Cross University; Doctor of Philosophy (PhD)
- Theses
- Doctor of Philosophy (PhD), Southern Cross University
- Publisher
- Southern Cross University
- Number of pages
- 130
- Identifiers
- 991013329628602368
- Copyright
- © Anita J. Marks 2024
- Academic Unit
- Faculty of Science and Engineering
- Resource Type
- Thesis