Non-vocal communication as an anti-predator strategy in scaled doves (Columbina squammata)

Different strategies have evolved in response to predation pressure. Many species use acoustic signals to communicate about the presence of predators, and some of them use non-vocal sounds. Here, we evaluated the role of the non-vocal sound produced by scaled doves (Columbina squammata) during escape takeoffs. Initially, we investigated the context of the non-vocal sound production to access the effects of natural threats on individuals’ escape response. Then, we used simulated attacks (a direct running movement toward the focal individuals) to confirm the preliminary observations and to evaluate how position in the group affects escape response and vigilance. For both the observational and experimental parts, we registered, among other variables, the occurrence of takeoff flight, if it was followed by a production of non-vocal sound, the position of the individuals within the flock and their response (e.g., stay, flew, vigilance). We observed that both solitary and flocked individuals produce non-vocal sounds during takeoff flights, although it was more commonly registered for flocks. The production of the non-vocal sound elicited a faster escape response on flock members, and individuals at the center of the flock showed a higher probability to takeoff. The results suggest that the non-vocal sound may signal information about predation risk and that it may be directed both to conspecifics and to the predator itself. Our results therefore contribute to the understanding of the evolution of mechanical sound production in birds and shed some light on its function as a communication signal, especially under a predation context.