Acoustic behaviour of bottlenose dolphins under human care while performing synchronous aerial jumps

Synchronous behaviours occur when two or more animals display the same behaviou r at the same time. However, the mechanisms underlying this synchrony are not we l l understood. In this study, we carried out an experiment to determine whether or not Bottlenose dolphins use acoustic cues when performing a known synchronised exercise. For this, we recorded three dolphins while they performed requested aerial jumps both individually or synchronously in pairs, with a hydrophone array and a 360 underwater video camera allowing the identification of the subject emitting vocalisations. Results indicated that in pairs, dolphins synchronised their jumps 100% of the time. Whether they jumped alone or in pairs, they produced click trains before and after 92% of jumps. No whistles or burst-pulsed sounds were emitted by the animals during the exercise. The acoustic localisation process allowed the successf u l identification of the vocalising subject in 19.8% of a l l cases (N = 141). Our study showed that in al l (n = 28) but one successf u l localisations, the click trains were produced by the same individual. It is worth noting that this individual was the oldest female of the group. This paper provides evidence suggesting that during synchronous behaviours, dolphins use acoustic cues, and more particularly click trains, to coordinate their movements; possibly by eavesdropping on the clicks or echoes produced by one individual leading the navigation.

Automated summary

The study suggests that dolphins use acoustic cues, specifically click trains, to coordinate their movements during synchronous behaviors. Dolphins were able to synchronize their jumps 100% of the time when performing in pairs, and in 92% of jumps, they produced click trains both before and after the jump. Successful identification of the vocalizing subject in most cases revealed that click trains were produced by the same individual, who happened to be the oldest female of the group.