On the sperm whale (Physeter macrocephalus) ecology, sociality and behavior off Ischia Island (Italy): patterns of sound production and acoustically measured growth

The main goal of this research is to contribute to the overall knowledge of the sperm whales’ (Physeter macrocephalus) ecology, sociality, and behavior in the Mediterranean Sea. The combined use of visual and acoustic methods allows me to: 1) give a detailed outline of the encounters around Ischia Island (Tyrrhenian Sea, Italy) over 2002-2015 period; 2) provide insights into the acoustic repertoire in encounters with social units (females with immatures), clusters of presumed/confirmed males and solitary individuals; this information was then used to model habitat suitability and use via analysis of different vocalization types, analyze a type of social sound (i.e. coda), and investigate an unusual tonal sound (i.e. trumpet); 3) present acoustically derived estimates of individual whale growth. This involved the application of acoustic methods to groups or individual sperm whales located in the area. Using passive acoustics to study animal behaviour is a developing field. As such, many of the recent publications describe methods, models and algorithms that can be used to investigate cetaceans in the wild. In this thesis I attempt to apply these tools to a larger sample size than previous studies in the Mediterranean Sea, taking advantage of the long-term data set of audio recordings made around Ischia Island between 2004 and 2015. The thesis is organized in 6 chapters. - Chapters 1 and 2 describe sperm whale general biology and acoustics; - Goal 1 is addressed in Chapter 3; it provides fundamental background information on the study area, the distribution of sperm whale encounters around Ischia Island, the individual photoidentification and group composition, as well as new insights on the habitat suitability, and diving/resting at surface cycle; - Goal 2 is addressed in Chapter 4; - Goal 3 is addressed in Chapter 5; - The final Chapter (#6) provides conclusions and outlines directions for future research.