Male aggression varies with consortship rate and habitat in a dolphin social network

  • Rebecca A. Hamilton
  • Teresa Borcuch
  • Simon J. Allen
  • William R. Cioffi
  • Vanni Bucci
  • Michael Krützen
  • Richard C. ConnorEmail author
Original Article


Coalitions and alliances exemplify the core elements of conflict and cooperation in animal societies. Ecological influences on alliance formation are more readily attributed to within-species variation where phylogenetic signals are muted. Remarkably, male Indo-Pacific bottlenose dolphins in Shark Bay, Western Australia, exhibit systematic spatial variation in alliance behavior, not simply within a species or population, but within a single social network. Moving SE-NW along Peron Peninsula in Shark Bay, males ally more often in trios than pairs, consort females more often, and exhibit greater seasonal movements. Ecological models predict more male-male conflict in the north, but sufficient observations of aggression are lacking. However, dolphins often incur marks, in the form of tooth rakes, during conflicts. Here we report that the incidence of new tooth rake marks varies systematically in the predicted pattern, with greater marking in the north, where males form more trios and consort females at a higher rate. While our previous work demonstrated that alliance complexity has an ecological component, we can now infer that ecological variation impacts the level of alliance-related conflict in Shark Bay.

Significance statement

To understand ecological influences on animal societies, researchers have focused on differences within species, where confounds due to evolutionary history are minimized. Such differences are usually found among geographically separated populations, but in Shark Bay, Western Australia, male dolphin alliance size and access to females increase along a spatial axis within a single social network. Here we report that aggression levels, evidenced by tooth rake marks, increase along the same axis. Alliances are of particular interest as they represent a complex kind of relationship, often implicated in the evolution of social intelligence. Our discovery of spatial variation in alliance behavior and aggression within a social network provides a unique opportunity to investigate the intersection of cognition, social structure, and ecology.


Aggression Wounds Reproductive strategy Competition Cetaceans Coalitions 



We thank the RAC Monkey Mia Dolphin Resort for their generous and ongoing support. Many generous people, including field volunteers, helped make this project possible. Stephanie King provided statistical advice. We express gratitude to the reviewers for their constructive suggestions.

Funding information

This study was supported by grants from the Australian Research Council (A19701144 and DP0346313), the Eppley Foundation for Research, the Seaworld Research and Rescue Foundation, the W. V. Scott Foundation, the National Geographical Society’s Committee for Research and Exploration, and NSF (1316800).

Compliance with ethical standards

Ethical approval

Data were collected under permits from the Western Australian Department of Parks and Wildlife. The University of Massachusetts at Dartmouth and the University of New South Wales provided animal ethics approvals for this study. All applicable international, national, and/or institutional guidelines for the use of animals were followed.

Competing interests

The authors declare that they have no competing interests.

Supplementary material

265_2019_2753_MOESM1_ESM.docx (5.4 mb)
ESM 1 (DOCX 5526 kb)


  1. Archie EA (2013) Wound healing in the wild: stress, sociality and energetic costs affect wound healing in natural populations. Parasite Immunol 35:374–385PubMedGoogle Scholar
  2. Archie EA, Altmann J, Alberts SC (2012) Social status predicts wound healing in wild baboons. Proc Natl Acad Sci U S A 109:9017–9022PubMedPubMedCentralGoogle Scholar
  3. Brown AM, Bejder L, Parra GL, Cagnazzi D, Hunt T, Smith JL, Allen SJ (2016) Sexual dimorphism and geographic variation in dorsal fin features of Australian humpback dolphins, Sousa sahulensis. Adv Mar Biol 73:273–314Google Scholar
  4. Chapais B (1995) Alliances as a means of competition in primates: evolutionary, developmental, and cognitive aspects. Am J Phys Anthropol 38:115–136Google Scholar
  5. Chapman CA, Rothman JM (2009) Within-species differences in primate social structure: evolution of plasticity and phylogenetic constraints. Primates 50:12–22PubMedGoogle Scholar
  6. Charpentier MJ, Drea CM (2013) Victims of infanticide and conspecific bite wounding in a female-dominant primate: a long-term study. PLoS ONE 8:e82830PubMedPubMedCentralGoogle Scholar
  7. Christian LM, Graham JE, Padgett DA, Glaser R, Kiecolt-Glaser JK (2006) Stress and wound healing. Neuroimmunomodulation 13:337–346PubMedGoogle Scholar
  8. Clutton-Brock T, Janson C (2012) Primate socioecology at the crossroads: past, present, and future. Evol Anthropol 21:136–150PubMedGoogle Scholar
  9. Connor RC (2007) Dolphin social intelligence: complex alliance relationships in bottlenose dolphins and a consideration of selective environments for extreme brain size evolution in mammals. Philos Trans R Soc B 362:587–602Google Scholar
  10. Connor RC, Krützen M (2015) Male dolphin alliances in Shark Bay: changing perspectives in a 30-year study. Anim Behav 103:223–235Google Scholar
  11. Connor RC, Whitehead H (2005) Alliances II: rates of encounter during resource utilization: a general model of intrasexual alliance formation in fission-fusion societies. Anim Behav 69:127–132Google Scholar
  12. Connor RC, Smolker RA, Richards AF (1992) Two levels of alliance formation among male bottlenose dolphins (Tursiops sp.). Proc Natl Acad Sci U S A 89:987–990PubMedPubMedCentralGoogle Scholar
  13. Connor RC, Wells R, Mann J, Read A (2000) The bottlenose dolphin: social relationships in a fission-fusion society. In: Mann J, Connor RC, Tyack PL, Whitehead H (eds) Cetacean societies: field studies of dolphins and whales. University of Chicago Press, Chicago, pp 91–126Google Scholar
  14. Connor RC, Watson-Capps JJ, Sherwin WB, Krützen M (2011) A new level of complexity in the male alliance networks of Indian Ocean bottlenose dolphins (Tursiops sp.). Biol Lett 7:623–626PubMedGoogle Scholar
  15. Connor RC, Cioffi WR, Randić S, Allen SJ, Watson-Capps J, Krützen M (2017) Male alliance behaviour and mating access varies with habitat in a dolphin social network. Sci Rep 7:46354PubMedPubMedCentralGoogle Scholar
  16. Detillion CE, Craft TK, Glasper ER, Prendergast BJ, DeVries AC (2004) Social facilitation of wound healing. Psychoneuroendocrino 29:1004–1011Google Scholar
  17. DeVries AC, Craft TK, Glasper ER, Neigh GN, Alexander JK (2007) 2006 Curt P. Richter award winner: social influences on stress responses and health. Psychoneuroendocrino 32:587–603Google Scholar
  18. Drews C (1996) Contexts and patterns of injuries in free-ranging male baboons (Papio cynocephalus). Behaviour 133:443–474Google Scholar
  19. Gerson HB, Hickie JP (1985) Head scarring on male narwhals (Monodon monoceros): evidence for aggressive tusk use. Can J Zool 63:2083–2087Google Scholar
  20. Harcourt A, de Waal FBM (1992) Coalitions and alliances in humans and other animals. Oxford University Press, OxfordGoogle Scholar
  21. Kappeler PM, Barrett L, Blumstein DT, Clutton-Brock TH (2013) Constraints and flexibility in mammalian social behaviour: introduction and synthesis. Philos Trans R Soc B 368:20120337Google Scholar
  22. Lee HH, Wallen MM, Krzyszczyk E, Mann J (2019) Every scar has a story: age and sex-specific conflict rates in wild bottlenose dolphins. Behav Ecol Sociobiol 73:63Google Scholar
  23. MacCormick HA, MacNulty DR, Bosacker AL, Lehman C, Bailey A, Anthony Collins D, Packer C (2012) Male and female aggression: lessons from sex, rank, age, and injury in olive baboons. Behav Ecol 23:684–691Google Scholar
  24. MacLeod CD (1998) Intraspecific scarring in odontocete cetaceans: an indicator of male ‘quality’ in aggressive social interactions? J Zool 244:71–77Google Scholar
  25. Maher CR, Burger JR (2011) Intraspecific variation in space use, group size, and mating systems of caviomorph rodents. J Mammal 92:54–64PubMedPubMedCentralGoogle Scholar
  26. Marley SA, Cheney B, Thompson PM (2013) Using tooth rakes to monitor population and sex differences in aggressive behaviour in bottlenose dolphins (Tursiops truncatus). Aquat Mamm 39:107–115Google Scholar
  27. Martin LB (2009) Stress and immunity in wild vertebrates: timing is everything. Gen Comp Endocrinol 163:70–76PubMedGoogle Scholar
  28. Martin A, Da Silva V (2006) Sexual dimorphism and body scarring in the boto (Amazon river dolphin) Inia geoffrensis. Mar Mammal Sci 22:25–33Google Scholar
  29. Nakagawa S, Schielzeth H (2012) A general and simple method for obtaining R2 from generalized linear mixed effects models. Methods Ecol Evol 4:133–142Google Scholar
  30. Orbach D, Packard J, Piwetz S, Würsig B (2015) Sex-specific variation in conspecific-acquired marking prevalence among dusky dolphins (Lagenorhynchus obscurus). Can J Zool 93:383–390Google Scholar
  31. Owen EC, Wells RS, Hofmann S (2002) Ranging and association patterns of paired and unpaired adult male Atlantic bottlenose dolphins, Tursiops truncatus, in Sarasota, Florida, provide no evidence for alternative male strategies. Can J Zool 80:2072–2089Google Scholar
  32. Pinheiro J, Bates D, DebRoy S, Sarkar D, R Development Core Team (2013) nlme: linear and nonlinear mixed effects models. R package version 3.1-108, URL
  33. R Core Team (2017) R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna Google Scholar
  34. Randic S, Connor RC, Sherwin WB, Krutzen M (2012) A novel mammalian social structure in Indo-Pacific bottlenose dolphins (Tursiops sp.): complex male alliances in an open social network. Proc R Soc Lond B 279:3083–3090Google Scholar
  35. Ross HM, Wilson B (1996) Violent interactions between bottlenose dolphins and harbour porpoises. Proc R Soc Lond B 263:283–286Google Scholar
  36. Rowe LE, Dawson SM (2009) Determining the sex of bottlenose dolphins from Doubtful Sound using dorsal fin photographs. Mar Mammal Sci 25:19–34Google Scholar
  37. Rubenstein DI (1981) Behavioural ecology of island feral horses. Equine Vet J 13:27–34Google Scholar
  38. Ruehlmann TE, Bernstein IS, Gordon TP, Balcaen P (1988) Wounding patterns in three species of captive macaques. Am J Primatol 14:125–134Google Scholar
  39. Samuels A, Gifford T (1997) A quantitative assessment of dominance relations among bottlenose dolphins. Mar Mammal Sci 13:70–99Google Scholar
  40. Schradin C (2013) Intraspecific variation in social organization by genetic variation, developmental plasticity, social flexibility or entirely extrinsic factors. Philos Trans R Soc B 368:20120346Google Scholar
  41. Scott EM, Mann J, Watson-Capps JJ, Sargeant BL, Connor RC (2005) Aggression in bottlenose dolphins: evidence for sexual coercion, male-male competition, and female tolerance through analysis of tooth-rake marks and behaviour. Behaviour 142:21–44Google Scholar
  42. Strier KB (2009) Seeing the forest through the seeds: mechanisms of primate behavioral diversity from individuals to populations and beyond. Curr Anthropol 50:213–228PubMedGoogle Scholar
  43. Thierry B (2008) Primate socioecology, the lost dream of ecological determinism. Evol Anthropol 17:93–96Google Scholar
  44. Tolley K, Read A, Wells R, Urian K, Scott M, Irvine A, Hohn A (1995) Sexual dimorphism in wild bottlenose dolphins (Tursiops truncatus) from Sarasota, Florida. J Mammal 76:1190–1198Google Scholar
  45. Whitehead H, Connor R (2005) Alliances I. How large should alliances be? Anim Behav 69:117–126Google Scholar
  46. Whitten PL, Smith EO (1984) Patterns of wounding in stumptail macaques (Macaca arctoides). Primates 25:326–336Google Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Biology DepartmentUniversity of Massachusetts DartmouthNorth DartmouthUSA
  2. 2.School of Biological SciencesUniversity of BristolBristolUK
  3. 3.School of Biological SciencesUniversity of Western AustraliaPerthAustralia
  4. 4.University Program in EcologyDuke University Marine LabBeaufortUSA
  5. 5.Evolutionary Genetics Group, Department of AnthropologyUniversity of ZurichZurichSwitzerland

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