Usually passive visual monitoring are preferred because they can concentrate various information in a single image or videos and are thus very efficient. However, if there is the possibility that the image and video quality may be too low for the task at hand or that other environmental constraints, passive acoustic monitoring might be a suitable solution in individual use cases. Although, there are approaches that employ both techniques simultaneously, their results generally do not yield significantly better performances (Sharma et al.) .
References:
M. Principato, L. Hasselwander, M. Stangner and R. Buettner, "Unlocking the Potential of Wind Energy With Machine Learning-based Avian Detection: A Call to Action", IEEE Access, Volume 11, 2023.
N. Sharma, A. Vijayeendra, V. Gopakumar, P. Patni, A. Bhat, "Automatic Identification of Bird Species using Audio/Video Processing", International Conference on Advancement Technology, ICONAT 2022, pages 1-6, 2022.