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Analysis of calls of killer whales, Orcinus orca, from Iceland and Norway

  • Fisheries and Oceans Canada, Pacific Biological Station
... The only published classification of calls from Iceland was conducted by Moore et al. (1988), who classified 24 call types based on a few hours of recordings from East Iceland. This was followed by a description of call type I36, the 'herding call' by Simon et al. (2006). ...
... This was followed by a description of call type I36, the 'herding call' by Simon et al. (2006). Comparisons to the Moore et al. (1988) catalogue were made whenever possible and call types that could not be compared or that were different from previously described calls were labelled I37 onwards. ...
... Further details on measurements for individual call types are provided in the text segment for each call type. Call type classification The call type is considered a likely match to call type I5 described by Moore et al. (1988). Moore et al. (1988) had described call types I5.1 to I5.4. ...
Technical Report
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Killer whales have been shown to produce stereotyped pulsed calls that can be classified into types with repertoires of call types varying between different social groups, populations and ecotypes. Closely related groups share part of their call type repertoire, thus, describing and comparing repertoires of killer whale calls from different groups and populations can provide important insight into their relatedness. Killer whales have long been known to occur in the coastal waters of Iceland, often found in large aggregations in herring grounds in the winter and summer. However, relatively few descriptions of call types have been conducted in this region. Here, we present a call type catalogue, based on recordings collected through dedicated research in Icelandic coastal waters that includes calls recorded from killer whales between 2008 and 2016. The catalogue aims to provide the first detailed description of the Icelandic killer whale call repertoire to provide insights into the acoustic behaviour of this population.
... For example, Norwegian killer whale pulsed calls exhibit strong harmonic banding, with fundamental frequencies that range between 0.04 and 4.8 kHz with durations between 0.11 and 2.2 s (Strager, 1995). Likewise, Icelandic killer whale pulsed calls have similar characteristics, with an average fundamental frequency between 0.16 and 3.28 kHz, and an average duration between 0.4 and 2.1 s (Moore et al., 1988). No detailed catalogue exists for vocalizations of killer whales occurring in the Northwest Atlantic, as these populations remain understudied compared to others. ...
... A comparison of the frequency resolution between spectrograms is provided in the supplementary appendix (Fig. S1). Previous literature analysis of killer whale calls reported maximum call frequencies below 10 kHz, which indicated that a 10 kHz max frequency spectrogram window was a high enough bandwidth for this analysis (Ford, 1984(Ford, , 1989Moore et al., 1988;Stafford, 2019;Madrigal et al., 2021). ...
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Killer whales (Orcinus orca) produce a variety of acoustic signal types used for communication: clicks, whistles, and pulsed calls. Discrete pulsed calls are highly stereotyped, repetitive, and unique to individual pods found around the world. Discriminating amongst pod specific calls can help determine population structure in killer whales and is used to track pod movements around oceans. Killer whale presence in the Canadian Arctic has increased substantially, but we have limited understanding of their ecology, movements, and stock identity. Two autonomous passive acoustic monitoring (PAM) hydrophones were deployed in the waters of Eclipse Sound and Milne Inlet, in northern Baffin Island, Nunavut, Canada, in August and September 2017. Eleven killer whale pulsed call types, three multiphonic and eight monophonic, are proposed and described using manual whistle contour extraction and feature normalization. Automated detection of echolocation clicks between 20 and 48 kHz demonstrated little to no overlap between killer whale calls and echolocation presumed to be narwhal, which suggests that narwhal remain audibly inconspicuous when killer whales are present. Describing the acoustic repertoire of killer whales seasonally present in the Canadian Arctic will aid in understanding their acoustic behaviour, seasonal movements, and ecological impacts. The calls described here provide a basis for future acoustic comparisons across the North Atlantic and aid in characterizing killer whale demographics and ecology, particularly for pods making seasonal incursions into Arctic waters.
... Multiple clans with associated group-specific dialects have been documented within Resident killer whale populations off the coasts of eastern Kamchatka (Filatova et al. 2015) and southern Alaska (Yurk et al. 2002), as well as British Columbia (Ford 1991). A variety of stereotyped calls have been described from herring-feeding populations of killer whales in Norway and Iceland, at least some of which appear to be group-specific (Moore et al. 1988;Strager 1995;Filatova et al. 2015). ...
The killer whale—the largest of the dolphins and the top marine predator––has a cosmopolitan distribution throughout the world’s oceans. Although globally it could be considered a generalist predator with a diverse diet, it is deeply divided into ecotypes, many of which have distinct foraging strategies involving only a narrow range of prey species. These ecotypes, which often exist in sympatry, are believed to arise from culturally driven dietary specializations that develop within matrilineal social groups and are transmitted among matriline members and across generations by social learning. Specializations are maintained by behavioral conformity and social insularity of lineages, which result in reproductive isolation and, ultimately, genetic divergence of ecotypes. Ecotypes have distinct patterns of seasonal distribution, group size, social organization, foraging behavior, and acoustic activity that are related to the type of prey being sought. Sophisticated cooperative foraging tactics have evolved in some ecotypes, and prey sharing within matrilineal social groups is common. Remarkable behavioral and demographic attributes have been documented in one well-studied ecotype, including lifelong natal philopatry without dispersal of either sex from the social group, vocal dialects that encode genealogical relatedness within lineages, and multi-decade long post-reproductive periods of females. Cultural traditions of killer whales, including foraging specializations, can be deeply rooted and resistant to change, which may limit the ability of ecotypes to adapt to sudden environmental variability.
... As shown in the north-eastern Pacific Ocean (Ford 1991), early studies of killer whale acoustics confirmed the existence of group-specific call repertoires in Norway, and suggested their existence in Icelandic waters as well (Moore et al. 1988, Strager 1995. Culturally transmitted call repertoires can provide insights into relatedness (Deecke et al. 2010). ...
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The first comprehensive review on North Atlantic killer whales Orcinus orca was published in 1988. Since then, a significant increase in published studies has substantially improved our understanding of occurrence patterns, major food sources, abundance and population structuring in the North‐east Atlantic. Dedicated studies on killer whales in the Mid‐ and West Atlantic were undertaken beginning in 2006, mainly following an increase in their presence due to rapidly changing environmental conditions in the Arctic regions of Canada and Greenland. Compiling 111 scientific articles and reports published from 1957 to date, this review assesses the current state of knowledge of North Atlantic killer whale populations. We reviewed distribution, abundance, movements, genetic structure, acoustics, population parameters, and threats, whilst highlighting the connection among regions from east to west. Our results indicated that, while North Atlantic killer whales should be recovering following the end of the harvest, culling and live captures in the 1980s, new emerging threats including chemical pollution, anthropogenic noise and increasing unregulated subsistence harvest in Greenland could be hampering this rebound. There is an urgent need to collect data on the abundance and population structure of killer whales in Greenland and Eastern Canada. A lack of information across most regions of the North Atlantic Ocean has prevented regional status assessments from being conducted. Ongoing and future studies should be aimed at collecting relevant data to undertake these assessments, particularly genetic samples and photo‐identification.
... The use of discrete calls, with and without an overlapping high-frequency component, was also observed in southeast Kamchatka killer whales 46 . In the Norwegian killer whale population, pod-specific dialects were reported 47 , and a number of call types used in different contexts were documented 47,48 , though much less is known about their vocalizations and social systems 49 . ...
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Large bioacoustic archives of wild animals are an important source to identify reappearing communication patterns, which can then be related to recurring behavioral patterns to advance the current understanding of intra-specific communication of non-human animals. A main challenge remains that most large-scale bioacoustic archives contain only a small percentage of animal vocalizations and a large amount of environmental noise, which makes it extremely difficult to manually retrieve sufficient vocalizations for further analysis – particularly important for species with advanced social systems and complex vocalizations. In this study deep neural networks were trained on 11,509 killer whale (Orcinus orca) signals and 34,848 noise segments. The resulting toolkit ORCA-SPOT was tested on a large-scale bioacoustic repository – the Orchive – comprising roughly 19,000 hours of killer whale underwater recordings. An automated segmentation of the entire Orchive recordings (about 2.2 years) took approximately 8 days. It achieved a time-based precision or positive-predictive-value (PPV) of 93.2% and an area-under-the-curve (AUC) of 0.9523. This approach enables an automated annotation procedure of large bioacoustics databases to extract killer whale sounds, which are essential for subsequent identification of significant communication patterns. The code will be publicly available in October 2019 to support the application of deep learning to bioaoucstic research. ORCA-SPOT can be adapted to other animal species.
... Dialects serve as an effective mechanism which indicates pod identity of individuals, maintains integrity of the social units and helps orcas to coordinate their activity (Ford 1984(Ford , 1991. Dialects have also been shown in populations of orcas inhabiting the waters of Alaska (Yurk et al. 2002), Norway (Moore et al. 1988) and Kamchatka (Filatova, in press). There are 21 types of discrete calls described in the acoustic repertoire of the Kamchatka orcas (Filatova, in press), whereas the other regions of western North Pacific waters remain unexplored. ...
Conference Paper
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The aim of our research is the description and classification of discrete calls of killer whale’s groups of Sakhalin, the Kuril Islands, and the comparison of the obtained types of discrete calls with the results of the investigation of acoustic repertoire of the Kamchatka population.
L’objectif de cette thèse est d’apporter différentes contributions méthodologiques en bioacoustique pour l’étude de la faune. En effet, la bioacoustique est une science récente, pluridisciplinaire et très efficace pour étudier et classifier un écosystème. Beaucoup d’études ont mis au point des procédés acoustiques pour étudier la faune à des échelles spécifiques, populationnelles, individuelles et comportementales. Ce travail de thèse propose d’étudier différents cas d’études présents dans ces quatre échelles d’analyses. L’objectif de cette thèse est de mettre en place des outils depuis la pose du matériel d’acquisition jusqu’à l’analyse des données pour l’ensemble des échelles présentées, de les discuter et de les mettre en perspective. La bioacoustique spécifique est illustrée ici par la classification automatique d’Orques, de Cachalots et d’oiseaux. Pour la bioacoustique populationnelle, la classification acoustique de clans d’Orques est étudiée. Puis l’échelle d’analyse s’affine et étudie les émissions sonores individuelles. Pour cela 3 cas d’études sont utilisés : la localisation individuelle d’Orques, de Cachalots et d’oiseaux. Ladernière échelle est appelée bioacoustique comportementale, elle a pour but de mettre en corrélation des comportements avec des émissions acoustiques. Pour cela, l’influence du trafic maritime sur les Dauphins tachetés pantropicaux et l’impact de stimuli chimiques chez la Baleine à bosse est étudié. Nous avons volontairement fait le choix de sélectionner différentes espèces produisant des types de signaux bien différents (stationnaires vs transitoires) évoluant dans des milieux différents (marins vs terrestres) afin d’homogénéiser les méthodes d’analyses pour faciliter le développement de nouvelles études en bioacoustique. Chaque cas d’étude présente des résultats intéressants en terme de bioacoustique et d’écologie comportementale. Ces résultats sont comparés avec la bibliographie. Puis, les résultats de chaque cas d’étude permettent de valider les méthodes proposées dans cette thèse. Les apports méthodologiques de cette thèse sont synthétisés, comparés et discutés, notamment l’impact des signaux stationnaires et transitoires, des milieux (marin et terrestre) sur la mise en place des méthodes. Les méthodes supervisées et non supervisées sont mises en comparaison. Les méthodes proposées ont été testées et validées sur certains protocoles de données massives (plusieurs dizaines de Tera). En conclusion, cette thèse montre que les méthodes supervisées (notamment le Deep Learning) étaient très bien adaptées pour la classification de signaux stationnaires en bioacoustique spécifique et populationnelle pour le milieu terrestre et marins. Puis les méthodes non supervisées (clustering et réduction de dimensionnalité) peuvent être utilisées dans le cadre des études en bioacoustique comportementale pour identifier les signaux d’intérêt. Enfin, la bioacoustique individuelle peut se traduire par des méthodes de localisation comme l’estimation du temps de délais d’arrivée inter-capteur, réalisable pour les signaux transitoires, et plus complexe pour les signaux stationnaires.
Killer whale call repertoires can provide information on social connections among groups and populations. Killer whales in Iceland and Norway exhibit similar ecology and behavior, are genetically related, and are presumed to have been in contact before the collapse of the Atlanto‐Scandian herring stock in the 1960s. However, photo‐identification suggests no recent movements between Iceland and Norway but regular movement between Iceland and Shetland. Acoustic recordings collected between 2005 and 2016 in Iceland, Norway, and Shetland were used to undertake a comprehensive comparison of call repertoires of Northeast Atlantic killer whales. Measurements of time and frequency parameters of calls from Iceland (n = 4,037) and Norway (n = 1,715) largely overlapped in distribution, and a discriminant function analysis had low correct classification rate. No call type matches were confirmed between Iceland and Norway or Shetland and Norway. Three call types matched between Iceland and Shetland. Therefore, this study suggests overall similarities in time and frequency parameters but some divergence in call type repertoires. This argues against presumed past contact between Icelandic and Norwegian killer whales and suggests that they may not have been one completely mixed population.
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