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Analysis of sperm whale (Physeter macrocephalus) vocalisa
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Abstract(s)
Os cachalotes são cetáceos cosmopolitas, demonstrando possuir uma estrutura social altamente complexa e vocalizações sofisticadas. Essas vocalizações, compostas quase inteiramente de sons de cliques, não são usadas apenas para alimantação em grandes profundidades, mas também para executar todas as outras funções da sua vida. As codas foram denominadas as séries curtas de 3 a 40 cliques, relacionadas a comunicação intraespecífica, manutenção de vínculos sociais e reconhecimento entre grupos. Cada cachalote usa diferentes tipos de codas, representando o seu repertório de codas, enquanto muitos tipos de codas e repertórios completos de codas são compartilhados entre diferentes indivíduos e grupos. Estudos de longa duração incorporando bacias oceânicas inteiras encontraram diferenças e semelhanças entre repertórios de codas e definiram clãs vocais, que são, pelo menos em algumas regiões, simpátricos. Nos Açores, os cachalotes são encontrados durante todo o ano, no entanto, poucos estudos foram dedicados aos repertórios de codas e clãs vocais simpátricos ainda não tinham sido detectados. Esta tese analisou os repertórios vocais de cinco cachalotes marcados com DTAGs durante o verão de 2020. Através do método IDCALL as codas foram classificadas e hierarquicamente agrupadas em clados e possíveis clãs vocais. O conjunto de dados foi alargado, incorporando codas dos Açores previamente analisadas, registadas entre 1988 e 2010, e adicionalmente comparados com outras regiões do Atlântico. Além disso, as DTAGs permitiram relacionar a produção de codas ao comportamento e movimento dos indivíduos. Os tipos de codas emitidos pelos cinco indivíduos marcados em 2020 foram investigados na tentativa de detetar relações com a fase de mergulho, atividade, profundidade e hora do dia. Dois indivíduos marcados em 2020 demonstraram um repertório de codas muito distinto ao que previamente havia sido registado nos Açores. As suas diferenças relativas aos restantes repertórios gravados nos Açores, que são caracterizados por codas regularmente espaçadas, sugerem a existência de dois clãs vocais simpátricos, que não foram descritos até agora. Os repertórios de codas demonstraram independência do ano de gravação, reforçando a estabilidade dos repertórios de codas nos Açores ao longo do tempo. Além disso, a maioria dos repertórios exibiu semelhanças com o clã EC2 das Caraíbas. Embora a análise contextual não tenha mostrado relações claras dos tipos de coda com os comportamentos, reforçou as diferenças individuais que haviam sido observadas anteriormente no uso do tipo de coda, além de ter indicado um aumento da frequência e diversidade de codas durante fases à superfície, atividades não relacionadas com alimentação, e durante o dia. Análises futuras e persistentes e o aumento do conjunto de dados serão necessários para confirmar a existência de clãs vocais e relações contextuais de produção de codas.
ABSTRACT: Sperm whales are worldwide distributed cetaceans, demonstrating a highly complex social structure and sophisticated vocalisations. These vocalisations, made up mostly of click sounds, are used for foraging in great depths, but also to perform many other live functions. Short series of 3 to 40 clicks were termed codas, which were related to intraspecific communication, maintenance of social bonds and recognition between groups. Each sperm whale uses different types of codas, representing its coda repertoire, while many coda types and even complete coda repertoires are shared between different individuals and groups. Long term studies incorporating entire ocean basins were able to find differences and similarities between coda repertoires and to define vocal clans, that are, at least in some regions, sympatric. In the Azores, sperm whales are found year-round, yet few studies have been dedicated to coda repertoires and sympatric vocal clans had not yet been discovered. This thesis analysed the vocal repertoires of five sperm whales tagged with DTAGs during summer 2020. Via the IDCALL-method, codas were classified and hierarchically clustered into clades and possible vocal clans. The dataset was enlarged by incorporating previously analysed codas from the Azores, recorded between 1988 and 2010, and additionally compared to other regions in the Atlantic. Furthermore, DTAGs allowed to relate the coda production to behavior and movement of individuals. The coda types emitted by the five individuals tagged in 2020 were investigated for relations to dive phase, activity, depth, and diel pattern. Two individuals tagged in 2020 demonstrated a very distinctive coda repertoire that had former not been recorded. Their differences to the remaining repertoires documented in the Azores, which are characterized by the prevalence of regular-click-codas, suggests the existence of two sympatric vocal clans, that have previously not been described. Coda repertoires demonstrated independency from recording year, confirming the stability of coda repertoires in the Azores over time. Further, many repertoires exhibited similarities to the Caribbean EC2-clan. While contextual analysis did not show clear relationships of coda types in certain behavioural situations, it indeed affirmed previously observed individual differences of coda type use, additionally indicated increased frequency and diversity of codas during surface phases, non-foraging, and daytime hours. Future, persistent analysis and increase of datasets are required to confirm the observations about vocal clans and contextual relationships of coda production.
ABSTRACT: Sperm whales are worldwide distributed cetaceans, demonstrating a highly complex social structure and sophisticated vocalisations. These vocalisations, made up mostly of click sounds, are used for foraging in great depths, but also to perform many other live functions. Short series of 3 to 40 clicks were termed codas, which were related to intraspecific communication, maintenance of social bonds and recognition between groups. Each sperm whale uses different types of codas, representing its coda repertoire, while many coda types and even complete coda repertoires are shared between different individuals and groups. Long term studies incorporating entire ocean basins were able to find differences and similarities between coda repertoires and to define vocal clans, that are, at least in some regions, sympatric. In the Azores, sperm whales are found year-round, yet few studies have been dedicated to coda repertoires and sympatric vocal clans had not yet been discovered. This thesis analysed the vocal repertoires of five sperm whales tagged with DTAGs during summer 2020. Via the IDCALL-method, codas were classified and hierarchically clustered into clades and possible vocal clans. The dataset was enlarged by incorporating previously analysed codas from the Azores, recorded between 1988 and 2010, and additionally compared to other regions in the Atlantic. Furthermore, DTAGs allowed to relate the coda production to behavior and movement of individuals. The coda types emitted by the five individuals tagged in 2020 were investigated for relations to dive phase, activity, depth, and diel pattern. Two individuals tagged in 2020 demonstrated a very distinctive coda repertoire that had former not been recorded. Their differences to the remaining repertoires documented in the Azores, which are characterized by the prevalence of regular-click-codas, suggests the existence of two sympatric vocal clans, that have previously not been described. Coda repertoires demonstrated independency from recording year, confirming the stability of coda repertoires in the Azores over time. Further, many repertoires exhibited similarities to the Caribbean EC2-clan. While contextual analysis did not show clear relationships of coda types in certain behavioural situations, it indeed affirmed previously observed individual differences of coda type use, additionally indicated increased frequency and diversity of codas during surface phases, non-foraging, and daytime hours. Future, persistent analysis and increase of datasets are required to confirm the observations about vocal clans and contextual relationships of coda production.
Description
Dissertação de Mestrado, Estudos Integrados dos Oceanos, 28 de abril de 2023, Universidade dos Açores.
Keywords
Sperm Whale (Physeter macrocephalus) Azores
Citation
Kather, Sarah. (2022). "Analysis of sperm whale (Physeter macrocephalus) vocalisa". 66 p. (Dissertação de Mestrado em Estudos Integrados dos Oceanos). Ponta Delgada: Universidade dos Açores, 2022. Disponível em http://hdl.handle.net/10400.3/6754