Characterizing Chilean blue whale vocalizations with DTAGs : a test of using tag accelerometers for caller identification
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Vocal behavior of blue whales (Balaenoptera musculus) in the Gulf of Corcovado, Chile, was analysed using both audio and accelerometer data from digital acoustic recording tags (DTAGs). Over the course of three austral summers (2014, 2015 and 2016), seventeen tags were deployed, yielding 124 h of data. We report the occurrence of Southeast Pacific type 2 (SEP2) calls, which exhibit peak frequencies, durations and timing consistent with previous recordings made using towed and moored hydrophones. We also describe tonal downswept (D) calls, which have not been previously described for this population. As being able to accurately assign vocalizations to individual whales is fundamental for studying communication and for estimating population densities from call rates, we further examine the feasibility of using high-resolution DTAG accelerometers to identify low-frequency calls produced by tagged blue whales. We cross-correlated acoustic signals with simultaneous tri-axial accelerometer readings in order to analyse the phase match as well as the amplitude of accelerometer signals associated with low-frequency calls, which provides a quantitative method of determining if a call is associated with a detectable acceleration signal. Our results suggest that vocalizations from nearby individuals are also capable of registering accelerometer signals in the tagged whale's DTAG record. We cross-correlate acceleration vectors between calls to explore the possibility of using signature acceleration patterns associated with sounds produced within the tagged whale as a new method of identifying which accelerometer-detectable calls originate from the tagged animal.
Saddler , M R , Bocconcelli , A , Hickmott , L S , Chiang , G , Landea-Briones , R , Bahamonde , P A , Howes , G , Segre , P S & Sayigh , L S 2017 , ' Characterizing Chilean blue whale vocalizations with DTAGs : a test of using tag accelerometers for caller identification ' Journal of Experimental Biology , vol. 220 , no. 22 , pp. 4119-4129 . https://doi.org/10.1242/jeb.151498
Journal of Experimental Biology
© 2017 The Author(s). Published by The Company of Biologists Ltd. This work is made available online in accordance with the publisher’s policies. This is the final published version of the work, which was originally published at: https://doi.org/10.1242/jeb.151498
DescriptionFieldwork for this project was funded by the Melimoyu Ecosystem Research Institute Foundation and the Woods Hole Oceanographic Institution. Analysis was supported by aWoods Hole Oceanographic Institution Summer Student Fellowship.
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