Koala tree selection in a mixed-tenure landscape and post-fire implications Nicole Gallahar A,D , Kellie Leigh B and David Phalen C A Science, Economics and Insights Division, Department of Planning, Industry and Environment, Locked Bag 5022, Parramatta, NSW 2124, Australia. B Science for Wildlife, PO Box 286, Cammeray, NSW 2062, Australia. C Sydney School of Veterinary Science, Faculty of Science, University of Sydney, Private Mail Bag 4003, Narellan, NSW 2570, Australia. D Corresponding author. Email: ngal2752@alumni.sydney.edu.au Abstract Context. The more frequent and intense bushfires predicted under climate change are likely to heavily impact koalas living inside protected areas and intact forests, which makes koala habitat in asset protection zones more important. Understanding how koalas use different habitats in a mixed-tenure landscape can inform effective conservation management. Aims. The aims of this study were to determine (1) the species and size of trees used by koalas, (2) whether choice of daytime trees was affected by available proportions of tree species and sizes in koala home ranges, and (3) whether developed land was used as frequently as native forest. Methods. Tree use by koalas was determined by radio-tracking 10 koalas for an average of 12 months and recording the species and diameter of trees they occupied. To compare the proportions of tree species used by koalas with those available, tree availability was measured using random quadrats in the home ranges of five koalas that used forested areas extensively. The habitats used by 10 koalas were classified as native forest or developed land to investigate the importance of human-modified areas. Key results. Eucalyptus punctata was a preferred tree species, but each individual used four to nine species. Tree species were not chosen solely on the basis of available proportions; some species were selected preferentially. Half of the koalas used more developed land than native forest. Koalas preferentially used trees with larger diameters than the mean of available trees, and selected larger trees in developed areas than in native forest and when re-using trees. Conclusions. Despite the higher availability of trees in protected native forest at the site, 70% of the koalas used developed land in and around asset protection zones. Koalas whose home ranges were geographically close, but had different soil types and vegetation communities, were able to utilise different tree species. Implications. Koalas would benefit from protection of remnant native forests containing preferred trees on shale cap soil and conservation of native vegetation corridors along fence lines and in paddocks in developed areas because they are valuable resources and connect patchy landscapes. Protecting koalas on developed land improves their likelihood of surviving bushfires, allowing recolonisation of surrounding protected areas. Keywords: Phascolarctos cinereus, tree choice, tree diameter, habitat, developed land, Eucalyptus, post-fire impacts, bushfire. Received 6 December 2020, accepted 8 June 2021, published online 15 October 2021 Introduction Wildlife face different threats depending on the land tenures they occupy (Lunney et al. 2002a; McAlpine et al. 2015). For example, in urban and peri-urban areas, they are exposed to a combination of threats such as habitat loss and fragmentation and vehicle strike (Bladon et al. 2002; Dique et al. 2003; Griffith et al. 2013; Dexter et al. 2018), whereas in native forests, bushfire is a significant risk (Phillips et al. 2021). Understanding how wildlife use different habitats in mixed-tenure landscapes is essential to guiding conservation actions to manage threats (Rhodes et al. 2006). This is particularly important in light of the impacts of more frequent and intense bushfires and drought predicted under climate change (Lindenmayer et al. 2013; Crowther et al. 2014; Lunney et al. 2014; Gorissen et al. 2015; Butt et al. 2015; Mella et al. 2019). Insights into habitat use may be gained by studying the habitat choices made by individual CSIRO PUBLISHING Wildlife Research https://doi.org/10.1071/WR20206 Journal compilation Ó CSIRO 2021 www.publish.csiro.au/journals/wr