Bottlenose dolphins (Tursiops spp.) are amongst the best studied cetacean species in the world. Extensive research has been carried out on their vocalisations which generally fit into three categories; whistles, burst-pulsed sounds (BPS) and echolocation clicks. Whistles and BPS are predominantly used for communication while echolocation clicks are used during foraging and for orientation. However, despite the wide range of research on whistle use in bottlenose dolphins, there are still gaps in our knowledge of the functionality and contextual use, particularly in wild populations. There has also been limited research carried out on BPS.

Bottlenose dolphins use individually distinctive whistles known as “signature whistles”, which are developed in the first year of life. These are thought to be used for individual identification and group cohesion. It is also likely that signature whistles contain information about an individual’s motivational state. However, much of the information on signature whistles has come from captive studies as it is very difficult to identify vocalising individuals in the wild.

This study aims to build on the current knowledge of bottlenose dolphin acoustic communication using what has been learned from captive studies. The study will also aim to test for the presence of motivational ques within the dolphins’ social sounds by identifying changes in vocal parameters in relation to changes in behavioural states.

Since 1992 a group of wild dolphins have regularly been provisioned on a beach at the Tangalooma Island Resort on Moreton Island as part of a tourist educational attraction. Currently there are 11 animals in the program, including adults and young calves. Prior to the provisioning, the dolphins spend some time socializing in the shallow water adjacent to a nearby jetty. They arrive at the same time every night allowing for a hydrophone array to be set up in anticipation of their arrival. Using the differences of arrival times of the sounds to each hydrophone, the location of the sound can be identified, a process that is very difficult in wild populations. While the acoustic behaviour of the dolphins is being recorded, video footage, identification photographs and behavioural data is concurrently recorded, allowing for identification of vocalising individuals and a comparison with behavioural states.

Katya Ovsyanikova, who joined the lab in 2016, will initially describe the repertoire of the 11 individual dolphins and identify each individual's signature whistle. She will investigate the contextual use of these whistles during provisioning and then compare this use to the use by the same individuals outside of the provisioning setting. Barry McGovern, who joined the lab in 2017, will use the signature whistles to test for the presence of motivation ques with the dolphins’ social sounds by comparing whistle parameters during different behavioural states. He will also aim to describe BPS use in different social contexts. He will then take this information and explore whether these results are also evident in the rest of the bottlenose dolphin population in Moreton Bay.