Recording animal vocalizations from a UAV: bat echolocation during roost re-entry

Area of Science:

• Bioacoustics
• Wildlife Monitoring
• Robotics

Background:

• Unmanned Aerial Vehicles (UAVs) are increasingly used for wildlife monitoring.
• Direct recording of animal vocalizations via UAVs is challenging due to UAV-generated noise.
• Echolocating bats, like Tadarida brasiliensis, are suitable for UAV recording due to their flight characteristics.

Purpose of the Study:

• To achieve the first direct recordings of animal vocalizations using a UAV.
• To characterize echolocation signals of bats during group flight and roost re-entry.
• To assess the potential of UAVs as tools for bioacoustic monitoring.

Main Methods:

• A modified UAV was designed to minimize propeller noise interference with microphone recordings.
• UAV-based bioacoustic recordings were conducted during bat roost re-entry.
• Echolocation signals from Tadarida brasiliensis were analyzed for time-frequency characteristics.

Main Results:

• The study reports the first published characteristics of bat echolocation signals recorded from a UAV during group flight.
• Changes in inter-individual time-frequency signal shape were observed, suggesting adaptive call design in complex social settings.
• Successful recordings demonstrate UAVs' capability for in-situ bioacoustic data collection.

Conclusions:

• UAVs equipped with noise-reduction technology can successfully record bat echolocation signals.
• Observed variations in echolocation signals may indicate sophisticated communication strategies in bats.
• UAVs represent a promising advancement for non-invasive bioacoustic monitoring in natural habitats, with ethical considerations noted.