Investigating the drivers of temporal and spatial dynamics in urban forest bird acoustic patterns

Urban forests, combining the characteristics of urban habitats and forest ecosystems, play an increasingly crucial role in enhancing urban environmental quality and maintaining ecological balance, emerging as vital areas for biodiversity. Bird monitoring effectively evaluates changes in urban habitats and serves as an important indicator for ecosystem services and biodiversity health. However, the relationship between bird community characteristics and urban forest environments across seasons is not fully understood. In this regard, we employed passive acoustic monitoring (PAM) combined with acoustic diversity index (ADI), normalized difference soundscape index (NDSI) and power spectral density (PSD), to explore how habitat features impact the acoustic activity intensity of forest bird community. Sound collection was conducted for 48 h at 30 monitoring points in spring, autumn, and winter. The results indicated that the acoustic bird community in autumn exhibited an obvious dominance. Seasonal variation significantly influenced the correlation between green space soundscapes and vegetation types. Average tree height and distance to the forest edge were identified as main factors affecting bird diversity and dominance changes. In addition, vegetation features accounted for most of the variation in the frequency band distribution of birdsong over different temporal scales. This study highlights the considerable potential urban forests hold for supporting avian diversity. The utility of acoustic monitoring method in tracking biodiversity in urban forests is demonstrated by the findings. Through this efficient monitoring approach, we conducted an in-depth evaluation of the acoustic characteristics of birds in urban forests, providing new insights into biodiversity conservation in rapidly urbanizing environments.