Abstract
The global growth of wind energy can harm wildlife and ecosystems, especially airborne animals, which face high collision risks with turbine blades. While detailed knowledge of bird and bat collision risk exists for temperate regions, risk assessments for insects and bats in the Global South remain lacking. To fill this gap, we investigated the activity of bats and nocturnal insects in Thailand at different heights above the ground. To this end, we suspended ultrasonic detectors and sticky traps from a helium-filled balloon kite at 25, 50, 75, and 100 m above ground, and also mounted them on a 2 m post to record ground-level activity. We documented the rotor-swept zone of local wind turbines to range between 21 and 159 m above ground. Mostly bat species from the guild of open-space foragers were active within this zone, namely Mops plicatus, Taphozous theobaldi, T. melanopogon, Scotophilus kuhlii, S. heathii, and Myotis siligorensis. Aerial insects, including Diptera, Hemiptera, Lepidoptera, and others, were also present within the rotor-swept zone of local wind turbines. Our findings demonstrate that aerial hawking bats, specialized for hunting insects in open space, face a high collision risk at wind turbines in Southeast Asia. Wind turbines may also kill airborne insects like Diptera, Hemiptera, and Lepidoptera. To reduce bat fatalities at wind turbines, we advocate for effective mitigation measures, such as limiting turbine operation at night during periods of high bat activity and specific environmental conditions. Further, wind turbines should only be built at great distance of ecologically important habitats.