Acoustic and foraging behavior of a Baird’s beaked whale, Berardius bairdii, exposed to simulated sonar

To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by the Nature Publishing Group. The published article can be found at: http://www.nature.com/srep/index.html.Beaked whales are hypothesized to be particularly sensitive to anthropogenic noise, based on previous\ud strandings and limited experimental and observational data. However, few species have been studied in\ud detail. We describe the underwater behavior of a Baird’s beaked whale (Berardius bairdii) from the first\ud deployment of a multi-sensor acoustic tag on this species. The animal exhibited shallow (23 ± 15 m max\ud depth), intermediate (324 ± 49 m), and deep (1138 ± 243 m) dives. Echolocation clicks were produced with\ud a mean inter-click interval of approximately 300 ms and peak frequency of 25 kHz. Two deep dives included\ud presumed foraging behavior, with echolocation pulsed sounds (presumed prey capture attempts) associated\ud with increased maneuvering, and sustained inverted swimming during the bottom phase of the dive. A\ud controlled exposure to simulated mid-frequency active sonar (3.5-4 kHz) was conducted 4 hours after tag\ud deployment, and within 3 minutes of exposure onset, the tagged whale increased swim speed and body\ud movement, and continued to show unusual dive behavior for each of its next three dives, one of each type.\ud These are the first data on the acoustic foraging behavior in this largest beaked whale species, and the first\ud experimental demonstration of a response to simulated sonar