Using acoustic indices to detect interspecific bird interactions and behaviour

Communication networks and acoustic interactions play a crucial role in shaping animal communities by mediating information exchange between individuals. These interactions contribute to the biophonic component of the soundscape—the acoustic environment of a place—which is increasingly analysed to understand ecosystem structure and functioning. However, soundscape analysis has rarely been applied to investigate the dynamics of information exchange within and between species. In this study, we tested whether two acoustic indices, Acoustic Entropy and Acoustic Complexity, could effectively reflect intra‐ and interspecies responses to playback experiments in a forest bird community. Our results indicate that, in the absence of non‐biotic background noise, playback elicited vocalizations that altered the soundscape sufficiently to be reflected in acoustic index values. These changes in the indices also reflect the number of bird species responding to playback. However, this effect was observed only in experiments conducted under low‐noise conditions, outside the breeding period, and when alarm calls were broadcast—conditions where the acoustic background is likely to be lower. In contrast, under conditions where the acoustic background is likely to be higher, the indices were unable to detect changes in bird acoustic behaviour elicited through playback. Our study highlights that acoustic indices may be a promising tool for investigating the acoustic networks emerging from homo‐ and heterospecific communication within an ecosystem, provided that precautions are taken regarding the experimental environment, ensuring that the acoustic background is not excessively high.