Evidence of male alliance formation in a small dolphin community

Abstract

The photo-identification of uniquely marked individuals has revealed much about mammalian behaviour and social structure in recent decades. In bottlenose dolphins (Tursiops spp.), for example, the long-term tracking of individuals has unveiled considerable variation in social structure among populations and various spatio-temporal aspects of group formation. In this study, we investigated associations among individual males in a small community of Indo-Pacific bottlenose dolphins (T. aduncus) residing in an urbanized estuary in southwestern Australia. Given the relative proximity of our study area to other populations in which complex male alliances form for the purpose of mate acquisition, we used long-term photo-identification records and social analyses to assess whether such alliances also occur in smaller and more isolated settings. Our work revealed strong social bonds and long-term, non-random associations among individual males, suggesting the occurrence of male alliances. Behavioural observations of alliances interacting with potentially receptive adult females from the estuary community and from adjacent communities, and exhibiting sexual display behaviours near females, suggest that these alliances occur in a reproductive context. As the first formal analysis indicating the occurrence of male alliances outside Shark Bay along the vast western coastline of Australia, this study complements previous research and extends our understanding of the evolutionary and ecological processes that drive alliance formation.

Individual identification and photographic techniques in mammalian ecological and behavioural research—Part 2: Field studies and applications

“…Our understanding of animal social behaviour has advanced greatly with the development of various individual identification techniques, so it is no surprise that socio-behavioural studies constitute a significant number of articles in this 2-part Special Issue (e.g., Chabanne et al 2022;Chui and Karczmarski 2022;Esteban et al 2022;Fedurek et al 2022;Goldenberg et al 2022;Marfurt et al 2022;Muller et al 2022;Tavares et al 2022). Among analytical tools, social network analysis offers a powerful framework that quantifies animal sociality as network metrics, which facilitate subsequent statistical analyses, and is commonly used in the study of animal social ecology (e.g., Gero et al 2013;Cheney et al 2016;Baker et al 2018;Balasubramaniam et al 2018;van Leeuwen et al 2018).…”