Vocal exchanges in wild bottlenose dolphins

This study investigated the behavioral context of stereotypic whistle exchanges in wild bottlenose dolphins off north-east Scotland to infer function from whistle usage. Concurrent acoustic and nonacoustic behavioral data sampling was conducted during focal follows. Passive acoustic localization using a four-element distributed array was used to identify vocal exchanges (i.e., whistles from different individuals within 3 s of each other). Vocal exchanges of stereotypic (two whistle types produced repeatedly by at least two animals) nature occurred during 12 focal follows from 10 separate days containing 108 whistles that could be localized. Exact randomization tests (10 000 iterations), using whistles from exchange and nonexchange periods within each follow, showed that the observed number of exchanges (i.e., whistles produced by different individuals within 5 s of each other) was significantly different than the value that resulted from randomization. Vocal exchanges occurred prior to dolphin subgroups joining in 9 out of 10 observed joins. Only 2 of 11 vocal exchanges were not followed by a join. Vocal exchanges of stereotyped whistles between individuals appear to be important in coordinating joins in wild dolphin groups. Further analysis of exchange whistles showed that their degree of stereotypy equalled that found in signature whistles.

Duke Scholars

Author Nicola Quick Marine Science and Conservation