Koalas on North Stradbroke Island: diet, tree use and reconstructed landscapes

Abstract

North Stradbroke Island lies 4 km off the coast of Queensland, Australia. It is home to one of the only naturally occurring island populations of koalas and it is mined for mineral sands. We analysed the diet and day use tree selections of koalas and recorded the tree species composition of revegetated and undisturbed landscapes at this location. We used faecal cuticle examination to compare the diet of koalas that used reconstructed landscapes with that of koalas that used undisturbed areas. Reconstructed landscapes that were composed of more than 95% diet and/or roost tree species had evidence of use by koalas. Eucalyptus robusta was the most commonly eaten and utilised species and there was no difference in general diet composition between koalas that used the revegetated landscape and those inhabiting undisturbed areas. Other species that were used for roosting and forage included E. racemosa, E. pilularis, Lophostemon confertus and Melaleuca quinquinerva. We observed individual differences and seasonal variation in the diet composition of radio-tracked koalas. These results suggest either flexibility in the diet choices of koalas, or individual preferences within groups of koalas. Our results also indicate that post-mining landscapes can provide habitat that will be used by koalas, which should encourage further efforts into habitat re-creation for native species.