Three Decades of Research on Passive Acoustic Monitoring in Bats: Systematic Review and Perspectives

ABSTRACT Introduction Passive acoustic monitoring (PAM) has transformed bat research by enabling non‐invasive, large‐scale and long‐term assessment of bat ecology and conservation status. Yet despite its rapid expansion, substantial methodological heterogeneity, pronounced geographic biases and fragmented taxonomic coverage continue to limit global synthesis and constrain the broader ecological and conservation value of PAM. Aims This review aims to: (1) map global geographic patterns and collaboration networks in PAM‐based bat research; (2) characterise temporal trends and major developmental phases; and (3) evaluate methodological practices across detector technologies, survey designs, monitoring cycles and data‐processing workflows. These objectives collectively provide a basis for identifying knowledge gaps, improving methodological coherence and guiding future monitoring and conservation efforts. Methods We systematically reviewed 935 peer‐reviewed studies from 1992 to 2023, compiling associated bibliometric, methodological and thematic metadata. Keyword co‐occurrence, thematic clustering, device‐use profiles, methodological categorisation and temporal trends were analysed using bibliometric tools and descriptive statistics. Results and Discussion Our review revealed strong geographic biases, with PAM research heavily concentrated in a few well‐studied regions. Research shifted from early detector‐focused work to broader conservation applications. Methodologically, fixed surveys, seasonal sampling and manual call processing remained dominant, though automated tools are increasingly adopted. Research themes were heavily skewed towards movement and identification, with ecosystem‐health and disturbance topics markedly underrepresented. Synthesis and Recommendations PAM research is advancing rapidly but remains geographically uneven and methodologically fragmented. Strengthening standardised yet flexible protocols and expanding capacity in under‐represented regions will be essential to fully realise its value for global bat conservation.