An Investigation of the Roles of Geomagnetic and Acoustic Cues in Whale Navigation and Orientation
Ann Allen, Ph.D., 2013
Peter Tyack, Advisor
This thesis investigates the roles of geomagnetic and acoustic cues in humpback whale navigation and orientation, and documents some effects of Navy sonar on beaked whales. The tracks of satellite tagged humpback whales migrating from Hawaii to Alaska were found to have systematic deviations from the most direct route to their destination. For each whale, a migration track was modeled using only geomagnetic inclination and intensity as navigation cues. The directions in which the observed and modeled tracks deviated from the direct route matched for 7 of 9 tracks, suggesting that migrating humpback whales may use geomagnetic navigation cues. This research also explores whether humpback whales migrating near-shore listen to sounds of snapping shrimp to detect an island. Visual tracking showed that the distance at which the whales avoided an island did not change with the assumed sound conditions. Propagation modeling of snapping shrimp sounds recorded on a hydrophone near the island suggested that they could be detected beyond the 2 km visual limit, indicating they could serve as a long-range indicator of an island. Lastly, this thesis identifies a prolonged avoidance reaction of a Blainville's beaked whale to playbacks of Navy mid-frequency active sonar and orca predation calls.