Male aggression varies with consortship rate and habitat in a dolphin social network
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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.
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.
KeywordsAggression 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.
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
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.
The authors declare that they have no competing interests.
- 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
- Chapais B (1995) Alliances as a means of competition in primates: evolutionary, developmental, and cognitive aspects. Am J Phys Anthropol 38:115–136Google Scholar
- 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
- Connor RC, Krützen M (2015) Male dolphin alliances in Shark Bay: changing perspectives in a 30-year study. Anim Behav 103:223–235Google Scholar
- 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
- 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
- Detillion CE, Craft TK, Glasper ER, Prendergast BJ, DeVries AC (2004) Social facilitation of wound healing. Psychoneuroendocrino 29:1004–1011Google Scholar
- 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
- Drews C (1996) Contexts and patterns of injuries in free-ranging male baboons (Papio cynocephalus). Behaviour 133:443–474Google Scholar
- Gerson HB, Hickie JP (1985) Head scarring on male narwhals (Monodon monoceros): evidence for aggressive tusk use. Can J Zool 63:2083–2087Google Scholar
- Harcourt A, de Waal FBM (1992) Coalitions and alliances in humans and other animals. Oxford University Press, OxfordGoogle Scholar
- 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
- 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
- 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
- MacLeod CD (1998) Intraspecific scarring in odontocete cetaceans: an indicator of male ‘quality’ in aggressive social interactions? J Zool 244:71–77Google Scholar
- 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
- 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
- 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
- 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
- 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
- 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 https://CRAN.R-project.org/package=nlme
- 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
- Ross HM, Wilson B (1996) Violent interactions between bottlenose dolphins and harbour porpoises. Proc R Soc Lond B 263:283–286Google Scholar
- 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
- Rubenstein DI (1981) Behavioural ecology of island feral horses. Equine Vet J 13:27–34Google Scholar
- Ruehlmann TE, Bernstein IS, Gordon TP, Balcaen P (1988) Wounding patterns in three species of captive macaques. Am J Primatol 14:125–134Google Scholar
- Samuels A, Gifford T (1997) A quantitative assessment of dominance relations among bottlenose dolphins. Mar Mammal Sci 13:70–99Google Scholar
- 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
- 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
- Thierry B (2008) Primate socioecology, the lost dream of ecological determinism. Evol Anthropol 17:93–96Google Scholar
- 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
- Whitehead H, Connor R (2005) Alliances I. How large should alliances be? Anim Behav 69:117–126Google Scholar
- Whitten PL, Smith EO (1984) Patterns of wounding in stumptail macaques (Macaca arctoides). Primates 25:326–336Google Scholar