Predicted impacts of climate change and extreme temperature events on the future distribution of fruit bat species in Australia

Fruit bats are important pollinators and seed dispersers whose distribution may be affected by climate change and extreme-temperature events. We assessed the potential impacts of those changes and events on the future distribution of fruit bats in Australia. Correlative species distribution modelling was used to predict the distribution of seven (based on data availability) tropical and temperate fruit bat species. We used bioclimatic variables, the number of days where temperature ≥42 °C (known to induce extreme heat stress and mortality in fruit bats), and land cover (a proxy for habitat) as predictors. An ensemble of machine-learning algorithms was used to make predictions for the current-day distribution and future (2050 and 2070) scenarios, using multiple emission scenarios (RCP 4.5 and 8.5) and global circulation models (Australian Community Climate and Earth System Simulator, Hadley Centre Global Environment Model Carbon Cycle, and the Model for Interdisciplinary Research on Climate). Our results predict, under current conditions, on average, 9.1 % and 90.8 % of the area are suitable and unsuitable, respectively. Under future scenarios, on average, 6.7 % and 89.7 % continued to be suitable and unsuitable, respectively, while there was a 1.1 % gain and 2.4 % loss in suitable areas. Under current conditions, we predict, on average, 5.6 % and 3.4 % are suitable inside and outside species’ IUCN-defined range, respectively. While under future scenarios, 4.8 % (4.4 % stable and 0.4 % gain) and 2.9 % (2.2 % stable and 0.6 % gain) are suitable inside and outside the range respectively. On average, the gain in areas inside the range covers 2703.5 grid cells of size 5 km, while outside the range it is 4070.3 cells. Under future scenarios, the loss in areas is predicted to be 1.2 % and 1.1 % on average, inside and outside species range respectively. Fruit bats are likely to respond to climate change and extreme temperatures by migrating to more suitable areas, including regions not historically inhabited by those species. Our results can be used for identifying areas at risk of new fruit-bat colonisation, such as human settlements and orchards, as well as areas that might be important for habitat conservation.