Kikuchi, S.; Kondo, N.; Koda, H.

Vocal exchange or turn-taking - an interaction in which vocalizer alternation occurs at very short intervals to avoid overlapping vocalizations - occurs not only in human conversation but also in animal communications, characterized by temporal regularities in the timing of spontaneous and response vocalizations. This temporal regularity has been observed in social mammals or primates, including humans, but little has been known about vocal exchange of call in birds, a highly vocal animal. Here, we experimentally manipulated a face-to-face setting with Java sparrows to observe their vocal exchange between two birds and analyzed its temporal regularity. The results showed that the temporal regularity of their vocal exchange was significantly different from that of primates. In particular, Java sparrows responded reflexively to the vocalizations of other individuals, but they showed no tendency to await the vocalizations of other individuals. Similar to behavioral synchrony, which is commonly observed in avian species, contagious vocalization possibly shapes avian vocal exchange. These results suggested the need for careful comparative studies of vocal exchange among social animals, considering the differences in the ecological backgrounds of group formation.