The objectives of this project were met through completion of four Work Packages. In Work Package 1, I analysed whistle contours from six dolphin species recorded in the tropical Pacific Ocean to quantify dolphin whistle repertoire diversity for the first time. I compared whistle these repertoires between species and determined that many whistle contours are shared between species but whistles that are unique to individual species also exist. Dolphins may be using these unique whistle-types to communicate species identity.
In Work Package 2, I conducted playback experiments with bottlenose dolphins to investigate whether they perceive species differences in whistles. The playbacks consisted of whistles produced by bottlenose dolphins, spotted dolphins and melon-headed whales. I conducted playback experiments with four independent groups of dolphins and conducted four playback sessions with each group. During the playbacks the dolphins were allowed to swim freely in their pools. I made underwater video and audio recordings of the dolphins before, during and after the playback. I analysed these recordings to investigate any behavioural reactions that occurred in response to playback of whistles produced by different species. Statistical comparisons showed that swim speed increased significantly when the species producing the playback whistle changed. This demonstrated that bottlenose dolphins perceive differences in the whistles produced by different species and react to those changes.
In Work Package 3, I examined a physiological response to whistles produced by different dolphin species by measuring heart rate during playbacks to bottlenose dolphins. The playback sequences used in this Work Package were the same as those that I used in Work Package 2. During playbacks, I recorded heart beats from the focal dolphin. I then calculated average heart rate in 2-second bins and compared the heart rate bins immediately before the first whistle in the playback, the first whistle after the species changed and the last whistle in the playback to the four successive heart rate bins in each case. I found no significant difference in heart rate. Heart rate is controlled by the autonomic nervous system and so my study shows no autonomic orienting or defense response to whistles produced by unknown individuals, regardless of species.
In Work Package 4, I developed four educational videos about dolphin communication for primary school children. These videos are multiple episodes of a news show called Dolphin Speak. In each episode the primary school-aged hosts introduce a topic and interview marine mammal scientists to answer questions about that topic. I developed study guides to accompany the videos. The videos and study guides are posted on the project website. I also presented results from my study at two international scientific conferences, at the University of St Andrews School of Biology Away Day and at a National Institute for Mathematical and Biological Synthesis (NIMBioS) Investigative Workshop on Bio-acoustic Structure. I was involved in several outreach activities, including presenting three talks on to students at local primary schools and running a booth on dolphin communication at the St Andrews Science Exploration day. I am currently preparing three manuscripts describing the results of this project for publication in peer reviewed journals.
