William E. Evans
Texas Inst. of Oceanogr., Texas A&M Univ., P.O. Box 1675, Galveston, TX 77553
Wang Ding
Inst. of Hydrobiol., Chinese Acad. of Sci., People's Republic of China
Bernd Wursig
Texas A&M Univ., Galveston, TX 77553
Spectral and statistical analyses were used to compare the whistle structure of six species of dolphin; Stenella longirostris, Stenella frontalis, Stenella attenuata, Lagenorhynchus obscurus, Tursiops truncatus, and Sotalia fluviatilis. A consistent pattern existed in the various coefficients of variation calculated for the different species. In general, the frequency variables had the lowest coefficients of variation (cv). The values of cv for maximum frequency were usually the lowest. Compared to other species Tursiops had relatively large coefficients of variation of the frequency variables indicating that the frequencies of Tursiops whistles were more diverse. The other five species had similar frequency ranges which had higher upper frequencies than Tursiops. The results of discriminate analysis indicated that here were significant differences between the whistle structures of the different species, and that these differences were related to taxonomic relations, body size, and habitat. The magnitude of the differences in whistle structure correlated with taxonomic relationships of the various species studied. The pelagic species emitted whistles in a relatively higher frequency range and greater frequency modulation than the coastal or riverine species.