Auditory Survey of Endangered Eurasian Bittern Using Microphone Arrays and Robot Audition.

Area of Science:

• Ornithology
• Bioacoustics
• Ecology

Background:

• Bioacoustics monitoring is crucial for studying elusive bird species.
• The endangered Eurasian bittern (Botaurus stellaris) is difficult to monitor due to its secretive nature and habitat.
• Accurate population and habitat data are vital for bittern conservation.

Purpose of the Study:

• To assess the practical effectiveness of sound localization technology for monitoring Eurasian bitterns.
• To investigate the use of microphone arrays and robot audition for detecting low-frequency bittern calls.
• To evaluate the feasibility of this technology in remote, vegetated wetland environments.

Main Methods:

• Simulated sound source localization of bittern calls with varying microphone array sizes and noise levels.
• Field monitoring of bitterns using small microphone arrays in Sarobetsu Mire, Hokkaido, Japan.
• Utilized HARK (Honda Research Institute, Audition for Robots with Kyoto University) software for sound analysis.

Main Results:

• Larger microphone arrays improved spectral detectability, while smaller arrays enhanced temporal detectability.
• Identified false detections in smaller arrays due to reverberation.
• Successfully localized calls from at least two male bitterns in a complex wetland environment.

Conclusions:

• This study demonstrates the first successful field localization of rare birds using small microphone arrays.
• The technology offers a non-invasive method for population surveys, behavior, and habitat studies of bitterns and other rare nocturnal birds.
• Future development of robust localization systems is needed to mitigate reverberation and false detections in challenging field conditions.