[MARMAM] New paper on North Atlantic killer whales

Volker Deecke vd2 at st-andrews.ac.uk
Thu Aug 18 08:39:19 PDT 2011

Dear colleagues,

The following paper has recently appeared in the journal Aquatic Biology:

Deecke, V. B., Nykänen, M., Foote, A. D. & Janik, V. M. 2011. Vocal behaviour and feeding ecology of killer whales (Orcinus orca) around Shetland, UK. Aquatic Biology, 13, 79–88.

ABSTRACT: Killer whales Orcinus orca are sighted regularly off Shetland, UK, but little is known about their numbers, diet and population identity. We aimed to relate vocal behaviour to diet of killer whales around Shetland in order to investigate population structure and differences in feeding strategies. Fieldwork was conducted in the summers of 2008 and 2009. We located killer whales through a sightings network and shore-based scans and collected photo-ID data, behavioural information, feeding data and acoustic recordings from a small boat. The majority of encounters (n = 14) were of small groups (1 to 15 individuals) travelling close to shore and feeding on marine mammals. Two encounters were with large groups (20+ individuals) feeding on herring Clupea harengus farther offshore. Seal-hunting groups vocalised rarely, producing pulsed calls, echolocation clicks and whistles almost exclusively when surface-active or milling after a kill. Herring-eating groups were largely silent during one encounter, but very vocal during the other. Analysis of pulsed calls identified 6 stereotyped call types for seal-hunting groups and 7 for herring-eating groups. No call types were shared between both kinds of groups. The vocal behaviour of seal-hunting groups showed striking parallels to that of Pacific marine mammal specialists and presumably evolved to decrease detection by acoustically sensitive prey. One call type produced by Shetland herring-eating killer whales matched a vocalisation that a previous study had described from Iceland and identified as a possible herding call that may function to concentrate herring during feeding. These findings point to behavioural and dietary specialisation among Shetland killer whales, which should be taken into account when making management decisions affecting these animals.

KEYWORDS: Dietary specialisation, Vocal behaviour, Feeding ecology, Killer whale, North Atlantic

Please contact me <vd2 at st-andrews.ac.uk<mailto:vd2 at st-andrews.ac.uk>> with any questions about this research.

All the best

Dr. Volker Deecke
Sea Mammal Research Unit
Scottish Oceans Institute
University of St. Andrews
St. Andrews, Fife, KY16 8LB
Scotland UK

Phone +44.1334.463459
Fax +44.1334.463443
The University of St Andrews is a charity registered in Scotland: No SC013532

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