Passive acoustic monitoring for assessing forest bird distribution and identifying conservationally important areas in a subtropical forest landscape

Passive acoustic monitoring (PAM) has recently been developed and used for long-term and/or large spatial scale surveys. PAM is expected to be one of the most efficient methods for assessing species distribution and examining the factors affect it, helping identify important areas for biodiversity conservation and inform the management plan. In this study, we tested the feasibility of the PAM for monitoring bird species and revealed some critical points to consider in improving or developing more widely applicable PAM. We conducted PAM in the subtropical forest landscape of Amami-Oshima Island, Japan, which harbors rich biodiversity (over 100 species), including endangered and/or endemic plants and animals. Nine endemic forest bird species were detected across recording locations. The effects of environmental factors on the four bird species were analyzed, excluding the five species that were commonly detected and did not require occupancy modeling. Different environmental factors influenced the occupancy probability of the four species examined according to their habitat preferences, which is consistent with previous studies. Our results suggest that the combination of PAM and occupancy model enables us to identify the bird's spatial occupancy pattern, associated environmental factors, and the important areas that should be protected for conservation. PAM is a relatively low-cost and non-invasive method that can be applied in various monitoring of biodiversity conservation areas.