Allied male dolphins use vocal exchanges to “bond at a distance”

Emma Chereskin, Richard C. Connor, Whitney R. Friedman, Frants H. Jensen, Simon J. Allen, Pernille M. Sørensen, Michael Krützen, Stephanie King

Research output: Contribution to journalArticle (Academic Journal)peer-review

22 Citations (Scopus)

Abstract

Vocal interactions are intrinsic features of social groups and can play a pivotal role in social bonding.1,2 Dunbar's social bonding hypothesis posits that vocal exchanges evolved to “groom at a distance” when social groups became too large or complex for individuals to devote time to physical bonding activities.1,3 Tests of this hypothesis in non-human primates, however, suggest that vocal exchanges occur between more strongly bonded individuals that engage in higher grooming rates4–7 and thus do not provide evidence for replacement of physical bonding. Here, we combine data on social bond strength, whistle exchange frequency, and affiliative contact behavior rates to test this hypothesis in wild male Indo-Pacific bottlenose dolphins, who form multi-level alliances that cooperate over access to females.8–10 We show that, although whistle exchanges are more likely to occur within the core alliance, they occur more frequently between those males that share weaker social bonds, i.e., between core allies that spend less time together, while the opposite occurs for affiliative physical contact behavior. This suggests that vocal exchanges function as a low-cost mechanism for male dolphins that spend less time in close proximity and engage in fewer affiliative contact behaviors to reinforce and maintain their valuable alliance relationships. Our findings provide new evidence outside of the primate lineage that vocal exchanges serve a bonding function and reveal that, as the social bonding hypothesis originally suggested, vocal exchanges can function as a replacement of physical bonding activities for individuals to maintain their important social relationships.

Original languageEnglish
Pages (from-to)1657-1663.e4
JournalCurrent Biology
Volume32
Issue number7
DOIs
Publication statusPublished - 11 Apr 2022

Bibliographical note

Funding Information:
This dolphin research was carried out on Guthaaguda, Malgana Sea Country, and we acknowledge the traditional owners of the region. We thank RAC Monkey Mia Dolphin Resort and the Department of Biodiversity, Conservation and Attractions (DBCA) Shark Bay Rangers for their continued support and assistance. We thank Michael Weiss for his sage advice on appropriate statistical methods. Permits for the scientific use of animals were obtained from the DBCA, Western Australia. The University of Bristol, University of Zurich, and University of Western Australia all granted animal ethics approvals. S.L.K. was supported by The Branco Weiss Fellowship —Society in Science and by grants from the National Geographic Society ( 050R-17 and 59136R-19 ). W.R.F. was supported by a grant from the National Geographic Society ( 9301-13 ).

Funding Information:
This dolphin research was carried out on Guthaaguda, Malgana Sea Country, and we acknowledge the traditional owners of the region. We thank RAC Monkey Mia Dolphin Resort and the Department of Biodiversity, Conservation and Attractions (DBCA) Shark Bay Rangers for their continued support and assistance. We thank Michael Weiss for his sage advice on appropriate statistical methods. Permits for the scientific use of animals were obtained from the DBCA, Western Australia. The University of Bristol, University of Zurich, and University of Western Australia all granted animal ethics approvals. S.L.K. was supported by The Branco Weiss Fellowship—Society in Science and by grants from the National Geographic Society (050R-17 and 59136R-19). W.R.F. was supported by a grant from the National Geographic Society (9301-13). Conceptualization, E.C. and S.L.K.; methodology, E.C. R.C.C. W.R.F. F.H.J. and S.L.K.; software, F.H.J.; formal analysis, E.C. and S.L.K.; investigation, E.C. R.C.C. W.R.F. F.H.J. S.J.A, P.M.S, M.K. and S.L.K.; resources, S.L.K. R.C.C. W.R.F. S.J.A. P.M.S. and M.K.; writing – original draft, E.C. and S.L.K.; writing – review & editing, E.C. R.C.C. W.R.F. F.H.J. S.J.A, P.M.S, M.K. and S.L.K.; visualization, E.C.; supervision, S.L.K.; funding acquisition, S.L.K. R.C.C. W.R.F. S.J.A. and M.K. The authors declare no competing interests.

Publisher Copyright:
© 2022 Elsevier Inc.

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