Influence of leaf chemistry on the dietary choice and habitat quality of the koala in western Queensland
University of Queensland
Koalas are a vulnerable native Australian animal. Queensland koala populations are estimated to decline by 53 percent from 1991 to 2033. Koalas are highly selective feeders, depending on eucalypt leaves for nutrition and water. The concentrations of nutrients and toxins in Eucalyptus leaves are highly variable and influenced by environmental factors including rainfall and temperature.
Increasing climate variability in Australia, driven by global climate change, poses a serious threat to koalas by reducing food quality and quantity, especially in semi-arid regions. In addition, the occupation patterns and foraging behaviours of the south-west Queensland koala populations were found to be significantly related to rainfall regimes and surface water. Hence, understanding the effect of climate variability on koala food quality and availability at the landscape scale can help identify potential habitat refuges where koalas can persist in times of prolonged drought. Leaf chemistry is proved to be important for determining food quality and driving koala tree choice, but there is no study of how leaf nutrition varies with climate variability at the regional landscape scale (10,000s km2).
This question is critical for understanding how climatic change is likely to influence koala food quality and population persistence in semi-arid regions within its geographic range.
This project is significant for koalas and potentially for other Australian wildlife. Inland koala populations, which are most susceptible to degradation of habitat due to drought and heatwaves, make up around ~60 percent of vulnerable koala populations in Queensland, New South Wales and the ACT. The relationship between koala populations, food resources and climatic change are complex and little-understood in semi-arid regions. This project will provide further understanding of this threat and potential solutions as the first study to explore how climate variability influences food quality and habitat suitability of koalas on a regional landscape scale.
Results will provide scientific advice to underpin koala habitat management and conservation in semi-arid agricultural regions, and can contribute to koala conservation in eastern populations which are likely to face drier, hotter weather in the future.
On a more general note, exploring such interactions can inform our understanding of habitat dynamics under changing environmental conditions for other Australian wildlife in semi-arid landscapes. This knowledge is critical in maintaining sustainable populations of both species and their habitats in conservation management.