Social complexity and communication in bottlenose dolphins

Abstract

Cooperation is widespread across the animal kingdom, serving a multitude of purposes from improving foraging efficiency to reproductive success. Often such cooperative behaviour is facilitated through the use of acoustic communication. In this thesis, I investigate the importance of communication for the coordination of cooperative behaviour and how sensory ecology can drive the evolution of cooperation. To address this, I focus on the bottlenose dolphin, a species well-known for its vocal flexibility and propensity for cooperative behaviour. First, I show that while dolphins performing a cooperative task when exposed to anthropogenic noise will increase their whistle amplitude and duration, their cooperative success still decreased with increasing noise (Chapter two). Thus, highlighting the importance of accounting for the impact of noise disturbance on wild animals that rely on communication to coordinate their behaviour. I then switch focus to the allied male bottlenose dolphins of Shark Bay, Western Australia. I first quantify the acoustic parameters of two vocalisations used extensively by male dolphins, whistles and pops, to estimate their communication range (Chapter three). I then investigate how habitat heterogeneity influences the active space of pops, which ultimately may influence alliance behaviour. I find that habitat heterogeneity is a major driver of cooperative group size and reproductive success in this population (Chapter four). Finally, I test the function of pop acoustic synchrony among allied male dolphins by using sound playbacks alongside drone-mounted video. I confirm the hypothesised function of pops as an agonistic signal to induce females to stay close, and while the results indicate acoustic synchrony could function as a coalitionary signal to promote social unity and cooperation among males, further research is needed (Chapter five). Combined, my findings highlight the importance of vocal communication for cooperative behaviour and how habitat heterogeneity and anthropogenic noise may impact cooperative strategies.

Date of Award	3 Oct 2023
Original language	English
Awarding Institution	University of Bristol
Supervisor	Stephanie L King (Supervisor), Frants Havmand Jensen (Supervisor) & Andrew N Radford (Supervisor)