SIGNATURE WHISTLE MODELS IN BOTTLENOSE DOLPHINS, TURSIOPS TRUNCATUS

Abstract

Bottlenose dolphins (Tursiops truncatus) develop signature whistles to convey identity information and maintain group cohesion. These animals are thought to be capable of vocal learning: they may incorporate whistle modulation patterns from community members into their own. It is unclear which members free-ranging calves use as models, however, and whether those members differ between wild and captive dolphins. Using 69 wild calves recorded in Florida between 1984 and 2012, I sought to identify a relationship between the strength of a calf's association with other dolphins during its development, and the similarity between their whistles. We found a significant correlation between the similarity of only the males' whistles to those of their associates (p < 0.05, n=32, 1428 comparisons). This correlation was not particularly strong, however (r = 0.027), suggesting that the positive correlation between association and whistle similarity for male dolphins is small. Meanwhile, a greater proportion of captive dolphins develop whistles very similar to those of their close associates than do free-ranging dolphins. These results suggest that wild and captive dolphins have different rules in signature whistle development, possibly governed by social group composition.