A Comparative Analysis of Whistles Recorded from Three Bottlenose Dolphin (Tursiops truncatus) Populations
Campbell, G. S. and R. H. Defran
Cetacean Behavior Laboratory, Department of Psychology, San Diego State University, San Diego, CA 92182.
Whistle vocalizations recorded from bottlenose dolphins (Tursiops truncatus) in three different geographic locations were compared. A total of 56 hours of acoustic data was collected in two proximate areas of the Eastern Temperate Pacific - San Diego, California (33 surveys / 29 schools) and Catalina Island, California (7 surveys / 7 schools); and one area of the western Caribbean - Turneffe Atoll, Belize (124 surveys / 46 schools). Nine whistle parameters (begin frequency, end frequency, minimum frequency, maximum frequency, frequency range, duration, number of inflection points, begin sweep, and end sweep) were analyzed using both univariate and linear discriminant analysis techniques. One-way ANOVA tests indicated statistically significant whistle variable differences for 18 of 27 comparisons among the three dolphin populations. Linear discriminant analyses also indicated consistent and significant differences in whistles between locations. Percent correct classification scores were generally high and ranged from 74% to 89% (50% chance level) in comparisons between two study locations, and were 73% (33% chance level) when the three locations were analyzed together. The spatial plot of the first two canonical discriminant functions indicated that whistles from the Pacific Ocean areas were more similar to each other than to those collected from the Caribbean. These data suggest that dolphin stocks or populations isolated from acoustic contact with one another presumably develop unique whistle characteristics as a result of behavioral or genetic drift. Further, dolphin whistle characteristics could potentially be used to differentiate between stocks, thus providing another means of studying population membership.
|
