Experimental influence of a non-vocal signal on the vigilance of the Scaled Dove (Columbina squammata)

In social contexts, information exchange between individuals is an efficient mechanism to avoid predation and coordinate escape attempts. Different signs are recognized in avian communication, such as chemical, visual and acoustic. Considering acoustic signals, the role of non-vocal communication in antipredatory contexts have been overlooked and needs to be better exploited. The scaled dove (Columbina squammata) is a cryptic bird that gathers in flocks and produces a strong mechanical sound during takeoff flights. Previous study demonstrated that the emission of the non-vocal sound was related to the presence of a potential threat and that it influences the response of the other group members. In this context, we tried to experimentally evaluate the effect of the non-vocal signal on the vigilance of the C. squammata. The experimental manipulation was based on the emission of three different playbacks (treatments): (1) C. squammata takeoff flight sound (non-vocal signal), (2) vocalization of C. squammata and (3) vocalization of the sympatric species Troglodytes aedon musculus. After each treatment, the vigilance rate of the focal individual was recorded during five minutes. Results demonstrated that the non-vocal signal significantly enhanced the vigilance rate of the focal animal when compared to the other treatments. Considering the observed results, it is possible to infer that the non-vocal signal of C. squammata must have an important role on the communication, being used to transmit valuable information about predation risk.