Vulnerability of bats to climate change and the potential consequences for their populations in Aotearoa New Zealand

Globally, rapid human-caused climate change is posing one of the greatest emerging pressures on species and ecosystems. Uncertainty remains about how species will react to changing climate, particularly how vulnerable or adaptable and resilient they will be to changes and whether they can move to remaining favourable habitats. Here we report on a rapid trait-based climate change vulnerability assessment for all bat taxa resident in Aotearoa New Zealand. We use 16 traits across three dimensions (sensitivity, low adaptive capacity, exposure) that could make bats highly vulnerable to climate change, review the potential consequences on their long-term population viability and recommend research required to understand vulnerability and potential adaptive management requirements. We assessed all five known endemic bat taxa under two greenhouse gas concentration scenarios (representative concentration pathways: RCP4.5, RCP8.5) for two future time periods (2040, 2090). One taxon (the greater short-tailed bat Mystacina rousta) was categorised as Highly Vulnerable by 2040 under RCP4.5, and the other four taxa demonstrated Latent Risk profiles, indicating they should be monitored closely to determine whether their potential responses to projected climate change happen earlier than 2090. All taxa were categorised as Highly Vulnerable by 2090 under the high emission RCP8.5 scenario. Although no overall conclusion can be reached about whether climate change will have positive, negative or mixed consequences for bats, the likely negative consequences include increased risk of predation, reduced availability and quality of roosting and foraging habitats, and increased thermal stress. Future research should focus on understanding the costs and benefits of changing climate on productivity and survival of bats and determining if management responses are desirable and feasible.