Application, progress, and future perspective of passive acoustic monitoring in terrestrial mammal research

Background & Aims: Passive acoustic monitoring (PAM) is an observational method that collects acoustic signals of wildlife and the surrounding environment using automatic sound recorders.PAM itself is a multidisciplinary technique, integrating biology, ecology, acoustics, and computer science, and was developed in the 1990s first to study bats and primates.Since then, PAM has been utilized in a variety of research contexts to study animal behavior, ecology, and conservation biology.However, a systematic review of the progress of the field is lacking.Progress: Here, we review how PAM has been used to monitor terrestrial mammal activity patterns, habitat use, species distribution, population size and density, biodiversity, and human influence.We also identify factors which prevent its wider application, such as the complexity of storing and managing acoustic data, limitations of acoustic indices,challenges associated with automated identification of species or individuals, and the overall cost of equipment.As a consequence, we observe limited use of PAM in terrestrial mammal research, especially in China.Perspective: Finally, we discuss potential novel applications of PAM to study terrestrial mammals.We highlight the importance of establishing and improving standardized PAM networks and data management platforms, developing citizen science programs, encouraging participation of more scientific institutions, and expanding the presence of acoustic monitors particularly throughout protected areas.PAM is an indispensable technique which can further support efforts to conserve biodiversity and increase ecological consciousness in China.