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Species and Threatened Status
The mahogany glider Petaurus gracilis is one of Australia's most threatened arboreal mammals. It is distinguished externally from other petaurids, particularly its closest relative the squirrel glider Petaurus norfolcensis, by its larger size, a long and relatively short-haired tail, and buff to mahogany brown belly. The mahogany glider is listed as 'Endangered' under the Queensland Nature Conservation Act 1992 (NCA) and the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act).
Habitat and distribution summary
Mahogany gliders are restricted to the southern Wet Tropics of north Queensland, from the Hull River (east of Tully) south to Ollera Creek, south-east of Ingham, and extending inland about 100km. Occurring in habitat below 120m elevation, mahogany gliders are highly mobile and dependent on continuous open forest or woodland to range freely. The main determinants of suitable habitat appear to be a sufficient variety of available flowering plant species to provide year-round food. A population viability analysis suggests that a minimum area of 8000ha containing 800 individuals is required for the long term.
Clearing has had a dramatic impact on mahogany glider habitat, the legacy of which is a severely fragmented and modified landscape comprising patches of various sizes, shapes, connectivity and condition. Only 20 percent (106,669ha) of former habitat remains available (Kemp et al. 2006). Altered fire regimes, weed invasion and intensive grazing threaten the structure and ecological integrity of remaining fragments.
Isolation of populations and the decline in habitat quality are major threats to the species' survival. Open forests suitable for mahogany gliders are converting from sclerophyll forest to pioneer rainforest communities because of altered, reduced fire regimes. These changes threaten the necessary structural components (i.e. hollows, open canopy) and food sources the mahogany glider requires. Weeds exacerbate this process by inhibiting grass cover necessary to maintain fire ecotones. Weeds might also affect fire intensity and the ability of understorey fuel loads to carry fire.
The impact of grazing pressure on habitat remains unquantified. Above a tolerance threshold, grazing may degrade the understorey species composition and cover, and alter long-term canopy maintenance. The spread of weeds can also be exacerbated through grazing pressure.
Major transport corridors disrupt mahogany glider movements; a number of road kills on the Bruce Highway have been recorded. Like other glider species, mahogany gliders may die after becoming entangled on barbed-wire fences.
The overall aim of this plan is to improve the conservation status of the mahogany glider through habitat protection and recovery, reduced threats and public involvement.
Summary of actions
Recovery plan actions include the following:
- Update mahogany glider habitat mapping and identify areas for protection, restoration and management.
- Develop strategies to conserve mahogany glider habitat on private lands.
- Identify, manage and monitor habitats threatened by encroaching rainforest.
- Implement habitat recovery burns at key sites and improve weed control.
- Promote a mahogany glider friendly-fencing scheme.
- Reduce threats arising from transport and easement corridors.
- Determine the population genetic structure of mahogany gliders.
- Review the recovery plan.