A glimpse into the foraging and movement behaviour of Nyctalus aviator; a complementary study by acoustic recording and GPS tracking

Species of open-space bats that are relatively large, such as bats from the genus Nyctalus, are considered as high-risk species for collisions with wind turbines (WTs). However, important information on their behaviour and movement ecology, such as the locations and altitudes at which they forage, is still fragmentary, while crucial for their conservation in light of the increasing threat posed by progressing WT construction. We adopted two different methods of microphone array recordings and GPS-tracking capturing data from different spatio-temporal scales in order to gain a complementary understanding of the echolocation and movement ecology of Nyctalus aviator, the largest open-space bat in Japan. Based on microphone array recordings, we found that echolocation calls during natural foraging are adapted for fast flight in open-space optimal for aerial-hawking. In addition, we attached a GPS tag that can simultaneously monitor feeding buzz occurrence, and confirmed that foraging occurred at 300 m altitude and that the flight altitude in mountainous areas is consistent with the turbine conflict zone, suggesting that the birdlike noctule is a high-risk species in Japan. Further investigations on this species could provide valuable insights into their foraging and movement ecology, facilitating the development of a risk assessment regarding WTs.