Publication Abstract

Whistle sequences in wild killer whales (Orcinus orca)

R. Riesch, J.K.B. Ford and F. Thomsen*

Combining different stereotyped vocal signals into specific sequences immensely increases the range of information that can be transferred between individuals. Both the temporal emission pattern and the behavioral context of vocal sequences have been described in detail for a variety of birds and mammals. Yet, in cetaceans the study of vocal sequences is just in its infancy. In the present study, we describe a new and rare stereotyped whistle (W7)as well as two whistle elements which are closely linked to whistle sequences: (1) stammers and (2) bridge-elements. Furthermore, we provide the first detailed analysis of whistle sequences in free ranging killer whales. A total of 1,140 whistle transitions in 192 whistle sequences recorded from resident killer whales off Vancouver Island were analyzed using common spectrographic analysis techniques. The frequency of occurrence of 12 different stereotyped whistle-types within the sequences was not randomly distributed and the transition patterns between whistles were also non-random. Further, sequences were closely tied to close-range behavioral interactions (in particular among males). Hence, we conclude that whistle sequences in wild killer whales are complex signal series and propose that they are most likely emitted by single individuals.

Reference

R. Riesch, J.K.B. Ford and F. Thomsen* (2008) Whistle sequences in wild killer whales (Orcinus orca). Journal of the Acoustical Society of America, 124; 1822-1829