Orchestration: The Movement and Vocal Behavior of Free-Ranging Norwegian Killer Whales (Orcinus Orca)

Ari Shapiro, Ph.D., 2008
Peter Tyack, Advisor

Studying the social and cultural transmission of behavior among animals helps to identify patterns and content of interaction. Killer whales likely acquire traits culturally based on their stable social groups, population-specific feeding behaviors and group-distinctive vocal repertoires. Digital tags were used to record the movements and vocalizations of Norwegian killer whales. These animals carousel feed, corralling herring into a ball before tail slapping, incapacitating and eating the fish. Periods of tail slapping were characterized by elevated movement variability, heightened vocal activity and call types containing orientation cues. Two types of behavioral sequence preceded the tight circling of carousel feeding. First, the animals swam directionally and in 2 of 3 instances were silent, suggesting they may have been eavesdropping. Second, the animals moved in broad horizontal loops and all 4 occasions were accompanied by vocal activity, indicating that this and tail slapping may benefit from social communication. Using human speech processing techniques, I considered whether calls are comprised of shared segments that can be recombined to form the stereotyped and variable repertoire. These shared segments performed as well as the traditional whole call types in a classification experiment and required less information to parse the vocalizations.