| Abstract: | This study provides evidence for interactive singing, or countersinging, in the dawn song of a male Mueller's gibbon. Tape-recorded answering calls from a simulated neighbor were initiated at the subject's baseline rate (every 18 sec), then successively at every 14 sec, 10 sec, 18 sec, 22 sec, and 26 sec. Two types of evidence for interactive singing were considered. First, the subject's initiation rate significantly increased when the initiation rate of the simulated neighbor increased (but did not decrease when the simulated neighbor's rate decreased). Second, the subject's rate of interruption of the simulated neighbor's vocalizations remained at the same low level regardless of the initiation rate of the simulated neighbor; these interruption rates were, in all cases, significantly lower than would have been expected by chance if interactive singing were not occurring. Evolutional value of interactive singing is considered in relation to demonstration of individual fitness and achievement of clear communication between neighboring groups. |
