My co-authors and I are pleased to announce the recent online release of the following article in Bioacoustics:
Call types of Bigg’s killer whales (Orcinus orca) in western Alaska: using vocal dialects to assess population structure. Sharpe DL, Castellote M, Wade PR, and Cornick LA ABSTRACT Bigg’s killer whales (Orcinus orca; i.e. ‘transient’ ecotype), as apex predators, are important to the dynamics of marine ecosystems, but little is known about their population structure in western Alaska. Currently, all Bigg’s killer whales in western Alaska are ascribed to a single broad stock for management under the US Marine Mammal Protection Act. However, recent nuclear microsatellite and mitochondrial DNA analyses indicate that this stock is likely comprised of genetically distinct sub-populations. In accordance with what is known about killer whale vocal dialects in other locations, we used the spatial distribution of group-specific call types to investigate the population structure of Bigg’s killer whales in this part of Alaska. Digital audio recordings were collected from 33 Bigg’s killer whale encounters throughout the Aleutian and Pribilof Islands in the summers of 2001–2007 and 2009–2010. Recorded calls were qualitatively classified into discrete types and then quantitatively described using 12 structural and time-frequency measures. Resulting call categories were validated using a random forest approach. A total of 36 call types and subtypes were identified across the entire study area, and regional patterns of call type use revealed three distinct dialects which correspond to proposed genetic delineations. Our results suggest that there are at least three acoustically and genetically distinct sub-populations in western Alaska, and we present an initial catalogue for this area describing the regional vocal repertoires of Bigg’s killer whale call types. For students, professors, and other scientists who are interested in our paper and have institutional access to articles, please use the following link: https://doi.org/10.1080/09524622.2017.1396562 For interested parties without the ability to circumvent pay-walls, a free copy can be obtained by clicking here: http://www.tandfonline.com/eprint/DwjAi5wHpjqzSFI5Ctzz/full . Please use this link only once. If you are unable to access the full article through either of these channels, don’t hesitate to contact me directly: dlynnsha...@hotmail.com Thank you for your interest, Deborah L. Sharpe, MSc
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