Dear colleagues,
We are excited to announce the publication of a behavioral study to discriminate fast-click series in Risso’s dolphins using digital tags. For those interested, the title and abstract are cited below: The Journal of Experimental Biology: doi: 10.1242/jeb.144295 Discrimination of fast click series produced by tagged Risso's dolphins (*Grampus griseus*) for echolocation or communication. P. Arranz, S. L. DeRuiter, A. K. Stimpert, S. Neves, A. S. Friedlaender, J. A. Goldbogen, F. Visser, J. Calambokidis,B. L. Southall, P. L. Tyack Abstract Early studies that categorized odontocete pulsed sounds had few means of discriminating signals used for biosonar-based foraging from those used for communication. This capability to identify the function of sounds is important for understanding and interpreting behavior; it is also essential for monitoring and mitigating potential disturbance from human activities. Archival tags were placed on free-ranging *Grampus griseus* to quantify and discriminate between pulsed sounds used for echolocation-based foraging and those used for communication. Two types of rapid click-series pulsed sounds, buzzes and burst pulses, were identified as produced by the tagged dolphins and classified using a Gaussian mixture model based on their duration, association with jerk *(i.e*., rapid change of acceleration), and temporal association with click trains. Buzzes followed regular echolocation clicks and coincided with a strong jerk signal from accelerometers on the tag. They consisted of series averaging 359 ± 210 (mean ± SD) clicks with an increasing repetition rate and relatively low amplitude. Burst pulses consisted of relatively short click series averaging 45 ± 54 clicks with decreasing repetition rate and longer inter-click interval that were less likely to be associated with regular echolocation and the jerk signal. These results suggest that the longer, relatively lower amplitude, jerk-associated buzzes are used in this species to capture prey, mostly during the bottom phase of foraging dives, as seen in other odontocetes. In contrast, the shorter, isolated burst pulses that are generally emitted by the dolphins while at or near the surface are used outside of a direct, known foraging context. PDF available upon request to [email protected] On behalf of the authors, Patricia Dr Patricia Arranz Postdoctoral Researcher Sea Mammal Research Unit Scottish Oceans Institute School of Biology University of St Andrews Scotland
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