Postgraduate Profiles

Kathryn Holmes

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Thesis: Ontogeny of male alliance formation in wild bottlenose dolphins: social network effects and behavioural strategies for building long-term cooperative partnerships

My research will focus on the dynamics of social relationships between juvenile male bottlenose dolphins in Shark Bay, Western Australia. Males in this population form multi-level alliances (i.e. alliances of alliances) with several unrelated individuals to gain access to mates, cooperative partnerships that are crucial for achieving reproductive success. Alliance partnerships are often long-term and begin to form prior to sexual maturity, a process we know little about. I aim to examine the roles of physical behaviour and communication in the development of these relationships during the juvenile period between weaning and sexual maturity. I will also investigate how juvenile males’ social networks affect their adult reproductive success. This research builds on a long-term study of the Shark Bay male bottlenose dolphin alliances by the Dolphin Alliance Project.

Why my research is important

Reproductive cooperation between unrelated males is unusual in the animal kingdom. In most species, unrelated males compete for fertilizations to maximize their own reproductive fitness, but in some species of birds, mammals and fish they reproduce cooperatively. An understudied aspect of this cooperation is how relationships develop, particularly in long-lived species where males form long-term cooperative partnerships. Social development and network building during the juvenile period is likely critical for the reproductive success of such males. Bottlenose dolphins are one of few species with a long period of post-weaning sexual immaturity relative to overall lifespan – the function of which is not fully understood. By exploring how the male alliances in Shark Bay form, my research will provide insight into the function and structure of juvenile social networks and the adult fitness consequences of social development during the juvenile period.

Another focus of my research is the vocal behaviour of juvenile males. Bottlenose dolphins produce a diverse array of sounds in social contexts, such as whistles and pops. In the Shark Bay population, pops are a threat vocalization used by adult males to control female movements, thus playing an important role in their reproductive success. Juvenile males also produce pops, but it is not known what function they serve. I will describe the development and contextual use of this vocalization and characterize the whistle repertoires of juvenile males. Additionally, my project will examine the role these vocalizations play in developing social relationships with future alliance partners. This work will further our understanding of the communication mechanisms used by animals to develop cooperative partnerships.

Funding

Play-herding behaviour of juvenile male bottlenose dolphins. Photo taken under research permits held by the Dolphin Alliance Project. Photo credit: Bronte Moore

Jun 2018

Jun 2021

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