Monitoring koala density and habitat condition to trigger management intervention in an overabundant population in south-eastern Australia (#264)
Some koala (Phascolarctos cinereus) populations in south-eastern Australia occur at high density, resulting in over-browsing of preferred food trees. The koala population on French Island, Victoria, has high fecundity and low mortality, resulting in over-abundance in many areas of preferred habitat. This issue is currently managed by Parks Victoria and the Department of Environment, Land, Water and Planning (State Government) via contraception and translocation. Preservation of habitat is the primary management goal, as this will achieve better overall biodiversity maintenance. Effective management, which requires setting priority areas for management within budget constraints, is an ongoing challenge. This long-term study is examining koala density along permanent transects, and correlating this with food tree condition. In prime habitat, koala density was up to 24 ha-1, vastly greater than the recommended 1 ha-1 for suitable Victorian koala habitat. At these densities there is significant defoliation of the more preferred food tress, which places them at serious risk. Data on the percentage of contracepted females across sites is also being collected, to examine how long it takes for population density to decline under the current management regime. This study will provide data on optimal population density for maintaining habitat in good condition, which will allow Parks Victoria and DELWP to prioritize their management efforts. Ultimately assessment of habitat condition will become the major data source for driving localised management intervention, as this is a more rapid, and therefore cheaper, method for determining when management intervention is required.