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OLI Grant: The Acoustic and Movement Dynamics of Free-ranging Norwegian Killer Whales

Grant Funded: 2005

The behavioral complexity, global distribution and status of the killer whale (Orcinus orca) as a top predator indicate that this species plays a significant ecological role in the marine environments that it populates. Most research exploring the acoustics, movements and natural history of these animals has taken place in British Columbia and Puget Sound, WA. Because this animal’s tremendous behavioral variety is rooted in local prey distributions and environmental features, this proposal describes a study to be conducted on another population in Vestfjord off the coast of northern Norway. The proposed research plan takes advantage of a few long-term studies of the Norwegian killer whales, including a catalog of almost 600 identified animals, records of pod composition and detailed descriptions of a highly coordinated group foraging context of corralling and incapacitating herring. We will synchronously use multiple, new digital recording tags that attach non-invasively to individual animals and continuously record their vocal behavior and three-dimensional movements. In addition, a linear array of hydrophones will be towed from a boat alongside the animals to localize all other vocalizations produced by non-tagged group members. This field setup of utilizing the tags and array in tandem will offer a unique view of how these animals use sound to coordinate their traveling and social hunting. The first set of objectives of this study use the ability to assign calls to individual animals to assess whether their stereotyped calls encode individually-distinctive features and how these features propagate through their environment and the possibility of call matching and exchanging between animals. A second objective is to associate the timing and frequency content of the calls with the movement data from the tags to test the hypothesis that acoustic activity helps maintain the coordinated traveling and foraging behaviors of the group. This will be the first research effort linking vocalizations with continuous sampling of underwater movements of free-ranging killer whales, offering a unique opportunity to ascertain how vocal activity coordinates certain features of their behavioral ecology in the wild.

Originally published: February 1, 2005