Date of Award
Master of Science (MS)
Susan E. Parks
bioacoustics, contact call, Eubalaena glacialis, identity signal
According to the source-filter theory proposed for human speech, physical attributes of the mammalian vocal production mechanism combine independently to result in individually distinctive vocalizations. In the case of stereotyped calls with all individuals producing a similar frequency contour, formants resulting from the shape and size of the vocal tract may be more likely to contain individually distinctive information than the fundamental frequency resulting from the vibrating source. However, the formant structure resulting from such filtering has been historically undervalued in the majority of studies addressing individual distinctiveness in non-human species. The upcall of the North Atlantic right whale (Eubalaena glacialis) is characterized as a stereotyped contact call, and visual inspection of upcall spectrograms confirms presence of a robust formant structure. Here I present results testing age, sex, and individual distinctiveness of upcalls recorded from archival, suction cup mounted tags (Dtags). Multiple measurements were made using the fundamental frequency contour, formant structure, and amplitude of the upcalls. These three variable groupings were then tested alone and in combination with other groupings to assign upcalls to age classes based on reproductive maturity, age classes based on size, sex, and individual whales. To compare multiple classification methods, I used both discriminant function analysis and a classification and regression tree to classify calls to appropriate groups. In all analyses, the percentage of calls correctly assigned to the correct group—age, sex, individual—was significantly higher than chance levels. These results represent the first quantitative analysis of individual distinctiveness in mysticete whales and provide a baseline for further development of acoustic detection techniques that could be used to noninvasively track movements of whales across multiple habitats.
McCordic, Jessica, "Discrimination of age, sex, and individual identity using the upcall of the North Atlantic right whale (Eubalaena glacialis)" (2015). Theses - ALL. 106.