Whistle use and whistle sharing by allied male bottlenose dolphins, Tursiops truncatus

Abstract

Abstract : Bottlenose dolphins, especially adult males, share several characteristics with terrestrial species that produce group-distinctive vocalizations. Males are long-lived, often reaching their early forties. In Sarasota Bay, Florida, pairs of males form close associations that develop over a period of years and usually last the lifetime of the individuals. The goal of this thesis was to determine the effect of the formation of these alliances on the whistles of male dolphins. Recordings of isolated and free-swimming, socializing individuals revealed that males produce similar whistle types in both contexts. Isolated alliance partners produced similar whistles, while non-partners did not. Males also produced more variant whistle types and had less stable whistle repertoires over time than females. Females' whistles were more likely to be similar to the whistles of males than of other females. Females may rely on whistle distinctiveness for mother-offspring recognition, while males may rely on whistle convergence to maintain specific social bonds. Signature whistles appear to be used as contact calls in male dolphins. Allied males produced signature whistles most often when separated from their partners and least often when with their partners. During partner separations and reunions, whistles tended to be produced around the time of the maximum partner separation and the initiation of a reunion. Signature whistles were found to be individually distinctive, consistent with their use as contact calls. The results of this thesis indicate that free-ranging male dolphins use whistles in the same way as females and captive dolphins. (38 tables, 41 figures, chapter refs.)