Establishing baselines for echolocating bat activity at wind farms in mainland Southeast Asia

Efforts to reduce bat fatalities caused by collisions with wind turbines in Southeast Asia are hampered by a lack of information on bat activity and factors influencing this at wind farms in the region. To address this deficit, we employed acoustic detectors to establish a baseline for bat activity at wind turbines in southern Vietnam for one year. Fieldwork confirmed the local occurrence of 22 bat species, whereas 11 were registered at the turbines. Bat activity at the turbines was greatest in May–October, although moderate-to-high and high levels of activity frequently occurred every month. Our findings suggest that rain and temperature may have limited utility for refining curtailment in the study area because they do not markedly reduce bat activity. However, this is unlikely to be true of the many areas experiencing greater rainfall and/or distinct winter periods in Southeast Asia. In demonstrating that increased windspeeds significantly reduce bat activity, our results also indicate curtailment at low wind speeds will be effective at reducing bat fatalities at wind farms in the region. As the first publicly available study to report bat activity and factors influencing this at a windfarm in Southeast Asia however, much remains to be learnt.