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Long-term associations among male sperm whales (Physeter macrocephalus)

Little is known about the social structure of male sperm whales (Physeter macrocephalus) after they leave their natal units. While previous studies found no evidence for preferred associations among males, the observation of mass-strandings consisting exclusively of males, suggest that they have str...

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Detalles Bibliográficos
Autores principales: Kobayashi, Hayao, Whitehead, Hal, Amano, Masao
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7757888/
https://www.ncbi.nlm.nih.gov/pubmed/33362216
http://dx.doi.org/10.1371/journal.pone.0244204
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author Kobayashi, Hayao
Whitehead, Hal
Amano, Masao
author_facet Kobayashi, Hayao
Whitehead, Hal
Amano, Masao
author_sort Kobayashi, Hayao
collection PubMed
description Little is known about the social structure of male sperm whales (Physeter macrocephalus) after they leave their natal units. While previous studies found no evidence for preferred associations among males, the observation of mass-strandings consisting exclusively of males, suggest that they have strong social bonds. To investigate the social associations among male sperm whales, we used half weight index of association, permutation tests and standardized lagged association rate models on a large photo-identification database collected between 2006 and 2017 in Nemuro Strait, Japan. Our results suggest that while male sperm whales are not as social as females, they do form long term associations, have preferred companionship, and forage in social proximity to each other. The best-fitting model to the standardized lagged association rate showed that associations among males last for at least 2.7 years and as most males leave the area after 2 years, associations may last for longer. Twenty dyads were observed associating over more than 2 years, for a maximum 5 years. One dyad was observed associating on 19 different days and clustered on 7 different days. Male associations may function to enhance foraging or to fend off predators. Such relationships seem to be adapted to a pelagic habitat with uncertain resource availability and predation pressure.
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spelling pubmed-77578882021-01-06 Long-term associations among male sperm whales (Physeter macrocephalus) Kobayashi, Hayao Whitehead, Hal Amano, Masao PLoS One Research Article Little is known about the social structure of male sperm whales (Physeter macrocephalus) after they leave their natal units. While previous studies found no evidence for preferred associations among males, the observation of mass-strandings consisting exclusively of males, suggest that they have strong social bonds. To investigate the social associations among male sperm whales, we used half weight index of association, permutation tests and standardized lagged association rate models on a large photo-identification database collected between 2006 and 2017 in Nemuro Strait, Japan. Our results suggest that while male sperm whales are not as social as females, they do form long term associations, have preferred companionship, and forage in social proximity to each other. The best-fitting model to the standardized lagged association rate showed that associations among males last for at least 2.7 years and as most males leave the area after 2 years, associations may last for longer. Twenty dyads were observed associating over more than 2 years, for a maximum 5 years. One dyad was observed associating on 19 different days and clustered on 7 different days. Male associations may function to enhance foraging or to fend off predators. Such relationships seem to be adapted to a pelagic habitat with uncertain resource availability and predation pressure. Public Library of Science 2020-12-23 /pmc/articles/PMC7757888/ /pubmed/33362216 http://dx.doi.org/10.1371/journal.pone.0244204 Text en © 2020 Kobayashi et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Kobayashi, Hayao
Whitehead, Hal
Amano, Masao
Long-term associations among male sperm whales (Physeter macrocephalus)
title Long-term associations among male sperm whales (Physeter macrocephalus)
title_full Long-term associations among male sperm whales (Physeter macrocephalus)
title_fullStr Long-term associations among male sperm whales (Physeter macrocephalus)
title_full_unstemmed Long-term associations among male sperm whales (Physeter macrocephalus)
title_short Long-term associations among male sperm whales (Physeter macrocephalus)
title_sort long-term associations among male sperm whales (physeter macrocephalus)
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7757888/
https://www.ncbi.nlm.nih.gov/pubmed/33362216
http://dx.doi.org/10.1371/journal.pone.0244204
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