Elsevier

Animal Behaviour

Volume 163, May 2020, Pages 73-84
Animal Behaviour

When personality matters: personality and social structure in wild bottlenose dolphins, Tursiops truncatus

https://doi.org/10.1016/j.anbehav.2020.03.001Get rights and content

Highlights

  • Wild bottlenose dolphins show individual differences in neophilia.

  • Bottlenose dolphin social network is structured by personality.

  • Bold dolphins have a central role in the social network.

  • Thus, bold dolphins probably play an important role in group cohesion and stability.

  • Thus, bold dolphins probably play an important role in spread of information.

There is increasing evidence that animal personality can affect many aspects of an individual's behaviour, life history and fitness. However, there have been few studies about the link between personality and social organization in the context of wild mammals in their own natural environments. This article reports on ecologically relevant data, linking experimental data from the wild to long-term social association data in a socially and cognitively complex mammal species (bottlenose dolphin, Tursiops truncatus). Here, I used behavioural data to describe personality differences between bottlenose dolphins and social network analysis to assess the relationship between personality and social structure. First, I measured the reaction of photo-identified individuals over time and across contexts as a trade-off between a novelty-seeking behaviour (boldness) and a novelty-averse behaviour (shyness). Second, I applied social network analysis to understand the link between the observed shy–bold continuum and social organization, while controlling for other factors that could contribute to affiliation. This study presents for the first time consistent individual differences in behavioural response to novelty, as a proxy for the shy–bold continuum, in wild bottlenose dolphins. Bold individuals had a central role in the social network with stronger associations than shy individuals, suggesting that bold individuals may play an important role in group cohesion, group stability and the spread of information through the network. Together, these findings provide insights into how a social network is structured by personality in wild bottlenose dolphins, with potential fitness consequences. Furthermore, this study provides additional evidence of the existence of social personalities in nonhuman animals and contributes to the understanding of the role of personality in determining the extent to which mammals associate with others.

Section snippets

Study Population and Site

Data were obtained from a long-term study of a social community of bottlenose dolphins on the northeastern coast of Sardinia, Italy (Fig. 1). Bottlenose dolphins live in this coastal environment, subject to significant use by humans, and interact with the fisheries, tourism and aquaculture industries (Díaz López, 2019).

The current study used data from 1017 bottlenose dolphin groups encountered from 2004 to 2013. This long-term data set allowed a good understanding of the abundance, community

Shy–Bold Continuum in Bottlenose Dolphins

Measurements of the individual response to novelty, as a proxy for the shy–bold continuum, were performed on 192 trials between 2004 and 2011 (N = 96 trials in the presence of an AHD and N = 96 trials in the presence of a UOb). Appendix Table A1 shows measurements of the reaction of each bottlenose dolphin to the novel and potentially threatening situations collected at various time intervals. The time interval between two consecutive trials ranged between 1 and 112 days for trials with an AHD

Discussion

The current study presents for the first time consistent (repeatable) individual differences in behavioural response to novelty, as a proxy for the shy–bold continuum, in wild bottlenose dolphins. The results also revealed novel evidence for a phenotypic link between boldness and sociability (i.e. boldness–sociability syndrome) in bottlenose dolphins. By controlling for multiple factors that bring individual bottlenose dolphins into groups, I found that association patterns vary as a function

Data Availability

All analyses were carried out, and can be reproduced, in the open-source programs SOCPROG 2.8 (Whitehead, 2009), in v. 3.6.0 QGIS Geographic Information System software (QGIS Development Team 2019), and in v. 1.8.1. of the statistics and graphics tool R (R Development Core Team, 2012). Data about the reaction of each individual bottlenose dolphin to the novel and potentially threatening situations are provided in the Appendix. Other data will be made available by the authors upon request.

Conflict of Interest

The author of this study declares that he has no conflict of interest.

Acknowledgments

I thank the members of the Bottlenose Dolphin Research Institute (BDRI) team between 2004 and 2013 who generously gave their time to help with field and photoidentification work. Many thanks are also extended to the BDRI students and volunteers who assisted with fieldwork. Special thanks also to Séverine Methion for her insightful comments and reviewing the manuscript and to Ariel for her support. I also thank Damien Farine, Ken Wilson, Hal Whitehead and the anonymous referees who provided

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