Perspectives on the Function of Behaviors Synchronized with Calling in Female Killer Whales, Orcinus orca: Patterns of Bubbling and Nodding in Bouts

Abstract

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.

Multimodal imitative learning and synchrony in cetaceans: A model for speech and singing evolution

“…A very interesting example of odontocete multimodal and synchronous social communication in orcas in controlled environments is given by Bowles et al (2016) . She and her collages described in two adult female killer whales two types of synchronous multimodal behaviors that consisted in bouts of stereotyped pulsed calls that occurred concurrently with bubble formations and nodding.…”

“…They suggest that vocalizations are important to calf survival, such as the mother’s signature whistle or primary elements of a group dialect, could be emphasized with synchronous behaviors. This is a very interesting hypothesis that deserves to be explored in the future, not only in the linking between bubbling or other synchronous behaviors with functional vocalization types in the orcas but in other cetaceans as well ( Bowles et al, 2016 ). Supporting these observations, recent experimental evidence suggests that during synchronous behaviors, dolphins use acoustic cues, and more particularly click trains, to coordinate their movements; possibly by eavesdropping on the clicks or echoes produced by one individual leading the navigation ( Jaakkola et al, 2018 ; King et al, 2021 ; Marulanda et al, 2021 ).…”