An accurate assessment of habitat loss and current threats to the mahogany glider (Petaurus gracilis)

Abstract

Despite the establishment of legislation to protect the remaining habitat of the endangered mahogany glider (Petaurus gracilis) there is an urgent need to understand where habitat remains and how it should be managed. Regional ecosystem mapping was used to identify the true extent of habitat loss from clearing and the extent of habitat degradation due to the transition to rainforest (where rainforest develops within in a sclerophyll community) and sclerophyll thickening (where saplings of local sclerophyllous species form a thick secondary tree layer). The total area of habitat available to mahogany gliders decreased by 49%, from 276 880 to 141 122 ha, as a result of clearing of vegetation for agriculture and other human activities. Of the habitat remaining, 51 870 ha was the most structurally complex and floristically diverse habitat type ‘Mixed Open Forest’, 55 760 ha was the more open and less diverse ‘Mixed Woodland’, 29 988 ha consisted of mainly single-canopy-species vegetation ‘Monotypic Stands’ and 3504 ha was classed as having only Emergent trees (trees emergent from a rainforest canopy) suitable for the mahogany glider. The loss of habitat occurred mostly on freehold land where it has decreased from 129 435 ha to 26 852 ha. Within the remaining Mixed Open Forest habitat, 45% is considered to have decreasing habitat suitability for the mahogany glider as a result of sclerophyll thickening or transition to rainforest, as is 26% of Mixed Woodland habitat, 33% of Monotypic Stands habitat and 8% of Emergent habitat. The impact of a large reduction in habitat area and decreasing habitat suitability has been compounded by habitat fragmentation. The remaining habitat must be actively managed to ensure its usefulness to the mahogany glider by implementing an appropriate fire regime and ensuring that habitat connectivity is maintained or increased.