Social communication and interactions among echolocating bats in urban ecosystems

Abstract

Recording changes in animal vocal communication in response to urbanisation has focused on species within the human audible range, while communication in ultrasonic range remains comparatively overlooked. In this thesis, I used C. gouldii as a model species because it is widely distributed across different habitats and is well adapted to urban areas. To understand how C. gouldii persists in urban areas, I focused on its social communication. By analysing their call measurements and call playback experiments, I found that C. gouldii has at least five types of social vocalisations, and that both conspecifics and heterospecifics were attracted to C. gouldii vocalisations. Social vocalisation rates increased in areas with substantial canopy cover, particularly when canopy exceeded 40% in urban areas. In addition, C. gouldii also adjusted its social vocalisations toward higher frequencies and shorter durations in urban areas. Moreover, in areas with limited roost density, C. gouldii colonies displayed a high network density, and individuals exhibited greater variation in their social vocalisations. These findings suggest that bat social vocalisations play an important role in enabling persistence and communication across diverse environments, including urban areas. They also provide preliminary guidance for habitat management, such as retaining and improving canopy cover and installing compensatory roosts in urban green spaces, extending insights beyond well-studied, human audible vocal communication of other animals. Further research should validate the specific functions of these social vocalisations, assess the potential use of acoustic lures for attracting bats to new installed compensatory roost in key habitats, and evaluate how urban noise influences bat communication.