Geographic variations of the Hawai’ian spinner dolphin (Stenella longirostris) whistle repertoire: Do they exist?

Abstract

In the present work, groups of spinner dolphins (Stenella longirostris) off four of the main Hawai’ian islands (Hawai’i, Lana’i, Maui, and O’ahu) have been studied. The whistle repertoire of dolphin groups from each island will be compared to search for geographic variations. In addition, behavioral, ecological, and acoustical variables have been quantified in order to correlate the dolphin whistle repertoire with specific behavioral and ecological factors. Geographic variations in the whistle repertoire of coastal bottlenose dolphins (Tursiops truncatus) from the Gulf of Mexico have been found. The differences were not attributable to different behavioral states, but were related to group structure (group size and contacts established between groups) and coastal habitat. These findings on the whistle repertoire of coastal bottlenose dolphins support the hypothesis that delphinid whistles serve to coordinate group behavior. Preliminary results on group structure of spinner dolphin groups off Hawai’i suggest that geographic variations should exist. Gulf of Mexico bottlenose and Hawai’ian spinner dolphin societies share several characteristics. Thus, it is expected that the Hawai’ian spinner dolphin whistle repertoire will show variations as does the bottlenose dolphin whistle repertoire. [This work was supported by a Leonida Memorial Scholarship and Seed Money Grant from the University of Hawai’i.]