Habitat loss and fragmentation is recognised as a leading cause for biodiversity decline. Current fragmentation hypotheses such as the classic island biogeography theory and the habitat amount hypothesis, highlight the importance of landscape features for species persistence. However, these differ in which aspects of fragmentation are important, i.e. patch size and isolation versus total habitat amount. Understanding which theory, if any, best applies to a species would benefit management of habitat and mitigate further loss. The island state of Tasmania, Australia is considered a haven for native mammals but faces increasing threats from habitat fragmentation, mostly in the Midlands’ agricultural landscape. The Eastern bettong (Bettongia gaimardi), extinct in the wild on mainland Australia, is directly threatened. Using occupancy modelling, and home range analyses we determine the presence and habitat use of the Eastern bettong in an agricultural landscape, and which fragmentation theory best applies to better inform landholders and industry partners managing the landscape. We modelled the species’ occupancy, by deploying 100 cameras in different habitat types across two seasons, recording vegetation and landscape variables. To provide finer scale results we then used GPS telemetry, spatial analysis, and SECR analysis at 3 sites to determine landscape and habitat features influencing home ranges and movement.
Results/Conclusions
Our occupancy results suggest that the amount of habitat within a 1km buffer (an average home range size of a bettong) was a better predictor of occupancy than patch size and patch isolation. Moreover habitat quality- stem density- was also positively associated with their presence. The home range and spatial analyses showed differing home range sizes across our three sampled sites. Preliminary results show significantly larger home ranges and amount of habitat in the larger woodland remnants, than smaller more fragmented areas. Habitat amount and fragmentation appear to both be important determinants of home range size. Ranges decrease with increasing fragmentation and woodland. Current analysis will include the population density and habitat quality to further explain these results. At present, our results support the habitat amount hypothesis. For a species that can utilise small patches and move within the matrix, the island biogeography theory may be less suitable. In this case, improving the quality of smaller patches, and or connecting small remnant patches may be just as valuable as preserving larger core and remnant woodland.