Occurrence and diet of killer whales in northern Norway: seasonal patterns relative to the distribution and abundance of Norwegian spring-spawning herring

Similä, Tiu; Holst, J.C.; Christensen, I.

doi:10.1139/cjfas-53-4-769

Cited by 44 publications

(66 citation statements)

References 6 publications

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“…A sub , these results point out that carousel feeding is dynamic and opportunistic, requirin a vast amount of herring biomass entered the fjords each winter (Similä et al, 1996).…”

mentioning

confidence: 72%

“…These fjords receive a massive influx of spring-spawning herring in the winter time, attracting foraging killer whales (Similä et al, 1996 These tags sampled sound at 96 kHz and movement at 50 Hz via a tri-axial accelerometer, a tri-axial magnetometer and a pressure sensor for depth. Although some of the animals in the 2006 dataset were introduced to sonar after a quiet pre-exposure session, only time periods before these exposures were analyzed here.…”

Section: General Materials and Methodsmentioning

confidence: 99%

“…They are characterized by stable social groups, populationspecific foraging strategies and vocal repertoires that are likely to be transmitted through learning. Their feeding behaviors include hunting fishes, cephalopods, sea turtles, sea birds, mustelids, pinnipeds and cetaceans (e.g., Martinez & Klinghammer, 1970;Christensen, 1978;Smith et al, 1981;Hoelzel, 1991;Jefferson et al, 1991;Baird et al, 1992;Similä & Ugarte, 1993;Matkin & Saulitis, 1994;Baird & Dill, 1995;Baird & Dill, 1996;Fertl et al, 1996;Similä et al, 1996;Ford et al, 1998;Baird & Whitehead, 2000;Ford & Ellis, 2006;Simon et al, 2006). The diversity of hunting strategies parallels the diversity of prey on which they feed.…”

Section: Killer Whales As Candidates For Using Culturementioning

confidence: 99%

“…This study benefited from selecting as its study species the killer whales that inhabit the fjords of northern Norway (Figure 1.1) in the wintertime as they follow spring-spawning herring (Clupea harengus) stocks (Similä et al, 1996). My research took advantage of a few long-term studies of the Norwegian killer whales, including a catalog of almost 600 identified animals, records of pod composition and detailed descriptions of carousel feeding, a group foraging behavior involving corralling and incapacitating herring.…”

Section: Introduction To Dissertation Researchmentioning

confidence: 99%

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Orchestration : the movement and vocal behavior of free-ranging Norwegian killer whales (Orcinus orca)

Shapiro¹

2008

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Studying the social and cultural transmission of behavior among animals helps to identify patterns of interaction and information content flowing between individuals. Killer whales are likely to acquire traits culturally based on their population-specific feeding behaviors and group-distinctive vocal repertoires. I used digital tags to explore the contributions of individual Norwegian killer whales to group carousel feeding and the relationships between vocal and non-vocal activity.Periods of tail slapping to incapacitate herring during feeding were characterized by elevated movement variability, heightened vocal activity and call types containing additional orientation cues. Tail slaps produced by tagged animals were identified using a rapid pitch change and occurred primarily within 20m of the surface. Two simultaneously tagged animals maneuvered similarly when tail slapping within 60s of one another, indicating that the position and composition of the herring ball influenced their behavior.Two types of behavioral sequence preceding the tight circling of carousel feeding were apparent. First, the animals engaged in periods of directional swimming. They were silent in 2 of 3 instances, suggesting they may have located other foraging groups by eavesdropping. Second, tagged animals made broad horizontal loops as they dove in a manner consistent with corralling. All 4 of these occasions were accompanied by vocal activity, indicating that this and tail slapping may benefit from social communication. No significant relationship between the call types and the actual movement measurements was found.Killer whale vocalizations traditionally have been classified into discrete call types. Using human speech processing techniques, I considered that calls are alternatively comprised of shared segments that can be recombined to form the stereotyped and variable repertoire. In a classification experiment, the characterization of calls using the whole call, a set of unshared segments, or a set of shared segments yielded equivalent performance. The shared segments required less information to parse the same vocalizations, suggesting a more parsimonious system of representation.This closer examination of the movements and vocalizations of Norwegian killer 3 whales, combined with future work on ontogeny and transmission, will inform our understanding of whether and how culture plays a role in achieving population-specific behaviors in this species. 4 ACKNOWLEDGEMENTS

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“…A sub , these results point out that carousel feeding is dynamic and opportunistic, requirin a vast amount of herring biomass entered the fjords each winter (Similä et al, 1996).…”

mentioning

confidence: 72%

Section: General Materials and Methodsmentioning

confidence: 99%

Section: Killer Whales As Candidates For Using Culturementioning

confidence: 99%

Section: Introduction To Dissertation Researchmentioning

confidence: 99%

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Orchestration : the movement and vocal behavior of free-ranging Norwegian killer whales (Orcinus orca)

Shapiro¹

2008

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“…the Northeast Atlantic, provide a suitable model for testing the potential that evolutionary divergence can be initiated and progress in sympatry, and in doing so, provide broader insights into the evolutionary outcomes of niche variation at a more general level. In the Northeast Atlantic waters, some degree of ecological diversification between groups, and relative seasonal specialization within groups, have been reported [29][30][31].…”

Section: Study Systemmentioning

confidence: 99%

Tracking niche variation over millennial timescales in sympatric killer whale lineages

Foote

Newton²,

Ávila-Arcos

et al. 2013

Proc. R. Soc. B.

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Niche variation owing to individual differences in ecology has been hypothesized to be an early stage of sympatric speciation. Yet to date, no study has tracked niche width over more than a few generations. In this study, we show the presence of isotopic niche variation over millennial timescales and investigate the evolutionary outcomes. Isotopic ratios were measured from tissue samples of sympatric killer whale Orcinus orca lineages from the North Sea, spanning over 10 000 years. Isotopic ratios spanned a range similar to the difference in isotopic values of two known prey items, herring Clupea harengus and harbour seal Phoca vitulina. Two proxies of the stage of speciation, lineage sorting of mitogenomes and genotypic clustering, were both weak to intermediate indicating that speciation has made little progress. Thus, our study confirms that even with the necessary ecological conditions, i.e. among-individual variation in ecology, it is difficult for sympatric speciation to progress in the face of gene flow. In contrast to some theoretical models, our empirical results suggest that sympatric speciation driven by among-individual differences in ecological niche is a slow process and may not reach completion. We argue that sympatric speciation is constrained in this system owing to the plastic nature of the behavioural traits under selection when hunting either mammals or fish.

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Occurrence of killer whales in Scottish inshore waters: temporal and spatial patterns relative to the distribution of declining harbour seal populations

Bolt

Harvey²,

Mandleberg³

et al. 2009

Aquatic Conservation

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Occurrence and diet of killer whales in northern Norway: seasonal patterns relative to the distribution and abundance of Norwegian spring-spawning herring

Cited by 44 publications

References 6 publications

Orchestration : the movement and vocal behavior of free-ranging Norwegian killer whales (Orcinus orca)

Orchestration : the movement and vocal behavior of free-ranging Norwegian killer whales (Orcinus orca)

Tracking niche variation over millennial timescales in sympatric killer whale lineages

Occurrence of killer whales in Scottish inshore waters: temporal and spatial patterns relative to the distribution of declining harbour seal populations

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