Data Sheet 1_Determining recorder distances from multicopters to avoid bat disturbance.pdf

The larger and heavier ConVecDro produced louder, and potentially more deterrent noise emissions, for Pipistrelloid and particularly for Nyctaloid groups. In contrast, the DJI Mavic 2 Pro had a weaker deterrent effect on bat activity, and only the Nyctaloid groups were affected. Based on our observations of both multicopters, the threshold value below which no echolocation group showed any detectable impact was 4.5 dB at 23 kHz.

In our setup, where the recording device was oriented towards the multicopter, it should be placed at 20 m for the DJI Mavic 2 Pro and at 36.0 m for the ConVecDro.</p>Discussion<p>The findings indicate that multicopter noise exerts a significant influence on bat activity, with the magnitude of the impact varying depending on the echolocation group and the specific characteristics of the multicopter noise profile. The ability to define noise threshold values for the different echolocation groups suggests that beyond a certain point, multicopter noise has no discernible effect on bat activity levels compared to a control group.</p>