International Journal of Comparative Psychology

In odontocetes, synchronous visible displays accompany a small proportion of vocalizations but the function of these multimodal signals is still unclear.  Bouts of stereotyped pulsed calls were collected from two adult female killer whales ( Orcinus orca ) concurrently with behavioral observations and the incidence of two synchronous behaviors, bubble streams and nodding, were measured.  Thirty-four hours of focal individual data were collected in the presence of dependent calves in 1993 and 1994.  Overall, 471 pulsed calls were attributed to the two subjects using synchronous behaviors or independent cues (proximity, localization by ear in air).  Both subjects used the same stereotyped pulsed call repertoire and they ordered calls within bouts similarly, despite dissimilar previous histories.  Both nodding and bubble streams were disproportionately associated with a subset of stereotyped pulsed calls, but the subset was different for the two behaviors.  General Linear Model analysis was used to predict the relative odds that the subjects would be swimming with calves given call class and attribution cue.  Bubbling was not associated with significant odds that a subject would be swimming with one or more calves, but nodding was associated with significantly higher odds and resting calls with lower odds.  Given these observations, synchronous behaviors in the presence of calves could function in one or more of the following ways: altering the signal value of calls, emphasizing an aspect of the social context, and facilitating learning.  All are possibilities at the interface between cognition and communication that would have interested Stan Kuczaj.