Killer whale vocal behavior during joining events.

Killer whale discrete pulsed calls (DPCs) have been hypothesized to maintain group cohesion, but the specific usage of these calls in relation to animal movements (trajectory, orientation, joinings, etc.) is not well understood. We examine here the use of DPCs by individuals and small groups involved in joining events. DPC rates were examined before and after joining events, while vocal behavior during call initiations and one‐ and two‐way vocal exchanges were also explored. Acoustic data were obtained using a triangular hydrophone array in Johnstone Strait in the summers of 2006 and 2007, while killer whale behaviors and locations were observed from a cliff using a video camera and theodolite, respectively. The relative arrival times of the killer whale sounds at each array hydrophone was used to determine the location of the vocalizing whale. Sounds were then associated in time and space with the corresponding killer whale’s position and behavior. Both DPC rates and the number of two‐way vocal exchanges...