Systematic acoustic surveys inform priority conservation areas for koalas in a modified landscape

Abstract

ContextLandscape modification due to urbanisation, agriculture and other human activity can have considerable impact on species’ distributions. Understanding the influence of both site and landscape level characteristics is essential for guiding conservation actions.ObjectivesOur study aimed to determine the influence of site and landscape level characteristics on the distribution of koalas and to identify areas for conservation action in a modified landscape.MethodsWe used passive acoustic surveys undertaken from October 2019 to January 2020 to determine site occupancy by koalas at 123 sites on the Mornington Peninsula, Victoria, Australia. We extracted variables for each site (within 100 m of recorders) and landscape (within 1 km of recorders) within a GIS. Site variables were tree cover, land use and soundscape, and landscape variables were tree cover, fragmentation, road density, and watercourse length.ResultsSite variables did not have an influence on site occupancy by koalas. Landscape-scale tree cover positively influenced, and road density negatively influenced site occupancy. We used our model to predict site occupancy in one-hectare grid cells across the landscape and found that public land was three times as likely as land under private tenure to have high probability of koala presence. Based on our results, increasing tree cover in landscapes where there already is 30% to 68% tree cover and a sealed road density of < 1 m per hectare would have the greatest benefit for koalas. Approximately 85 km2 (11%) of the Mornington Peninsula meets these criteria, with 87% of that land under private tenure.ConclusionsLandscape context is of primary importance for conservation of koalas in a modified landscape. Modelling should be used to improve the effectiveness of conservation actions.