Evidence that bottlenose dolphins can communicate with vocal signals to solve a cooperative task

Cooperation experiments have long been used to explore the cognition
underlying animals' coordination towards a shared goal. While the
ability to understand the need for a partner in a cooperative task has
been demonstrated in a number of species, there has been far less focus on
cooperation experiments that address the role of communication. In humans,
cooperative efforts can be enhanced by physical synchrony, and
coordination problems can be solved using spoken language. Indeed, human
children adapt to complex coordination problems by communicating with
vocal signals. Here, we investigate whether bottlenose dolphins can use
vocal signals to coordinate their behaviour in a cooperative
button-pressing task. The two dolphin dyads used in this study were
significantly more likely to cooperate successfully when they used
whistles prior to pressing their buttons, with whistling leading to
shorter button press intervals and more successful trials. Whistle timing
was important as the dolphins were significantly more likely to succeed if
they pushed their buttons together after the last whistle, rather than
pushing independently of whistle production. Bottlenose dolphins are well
known for cooperating extensively in the wild, and while it remains to be
seen how wild dolphins use communication to coordinate cooperation, our
results reveal that at least some dolphins are capable of using vocal
signals to facilitate the successful execution of coordinated, cooperative
actions.