Delphinid Whistle Repertoires: A comparison method between and within species

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This project will describe and compare the whistle repertoires of several delphinid species. Delphinids produce three types of sounds: clicks (used for echolocation), burst pulses (exact function is unknown) and whistles. Whistles are narrow-band, frequency-modulated calls and can be grouped into types by the basic shape (contour) of the whistle. Vocal repertoires (catalogues of the sound types a species produces) have been highly studied and described in many bird species. Despite the knowledge that delphinids use their whistles extensively in communication, comprehensive whistle repertoires are unavailable for many species. A delphinid whistle repertoire is made up of all the whistle types a species produces. However, the acoustic parameters of a whistle type can change between renditions while the contour of the whistle type remains the same. Existing research has focused on describing whistle repertoires in terms of acoustic parameters (variables, e.g. maximum and minimum frequencies) measured from whistle contours or very broad categorisation of whistle shapes (e.g. upsweep, downsweep or sinusoid) rather than analysis of individual whistle types. By describing and comparing whistle types and species whistle repertoires, we can obtain a more complete picture of delphinid communication, how this varies between species and how a changing ocean environment could affect delphinid communication systems. Through the description of whistle repertoires of delphinid species, I hope to discover whether some species produce more extensive and diverse whistle repertoire than others and how this can be related to differences in social structure, whether there is species-specific whistles-type use, as well as if species share whistle types and if so, by which species. I aim to identify the scale at which geographic differences in delphinid whistle repertoires occur and how increasing ocean noise impacts delphinid communication systems.