Java sparrows can modulate vocalizations in response to different light wavelengths

Bird vocalization plays a crucial role in species survival and ecological adaptation and is sensitive to environmental changes. Given the increasing light pollution following rapid urbanization, it is critical to understand their consequence on bird vocalization. We investigated the changes in calls and songs of Java Sparrows (Lonchura oryzivora) under different light types (control, blue, yellow, red, and white light). We found that bird vocalization was sensitive to different light types, as indicated by the changes of multiple variables of both calls and songs after the light treatments at night. Generally, bird calls exhibited limited parameter adjustments under different light wavelengths. In contrast, bird songs were more sensitive to blue light than other types, as indicated by the lower syllable duration, higher peak frequency, minimum frequency, maximum frequency and bandwidth. This suggests that Java sparrows may adapt their behavior in response to the level of light pollution to minimize the interference with their acoustic communication. Our results provide strong evidence for the impacts of light pollution on bird vocalization and highlight the divergent impacts of different light types on bird calls and songs, with implications for understanding bird behavior alterations in a world with increasing light pollution.