Six playback experimental designs fail to demonstrate acoustic preferences in common waxbills (Estrildidae: Estrilda astrild)

Playback experiments in controlled laboratory settings have been instrumental in studies of animal communication and signal evolution. Nonetheless, applying common methods to wild or non-model species can be challenging. We tested male and female common waxbills (Estrilda astrild) for behavioural preferences of conspecific vs. heterospecific songs, and of conspecific song vs. calls. Although common waxbills are related to model species used in this type of experiments, we could not demonstrate the predicted preference for conspecific over heterospecific song, or differential behavioural responses for conspecific song vs. calls. We confirm these results with experimental designs that either monitor movements, vocal responses, or active eliciting of playbacks, and that test birds in isolation or not, with or without visual stimuli accompanying playbacks. We discuss difficulties that may commonly apply to playback experiments with wild and social animals, and stress the importance of using simple discrimination tasks to validate common methods in novel species.