Delta and Reese, two male bottlenose dolphins born at Dolphin Research Center, show off their specialized suction cup tags. The tags allowed researchers to record the dolphins’ vocalizations during cooperative tasks with increasing background noise. DOLPHIN RESEARCH CENTER/Contributed

Dolphin Research Center (DRC), a not-for-profit research and education facility in the Florida Keys, collaborated with Pernille Sørensen and Dr. Stephanie King from the University of Bristol’s School of Biological Sciences in a research study revealing information about how dolphins working collaboratively are less successful in the presence of sound generated by humans. 

“We show that human-made noise directly affects the success of animals working together,” King said. “If noise makes groups of wild animals less efficient at performing cooperative actions, such as cooperative foraging, then this could have important negative consequences for individual health, and ultimately population health.”

The findings, published in the journal Current Biology, imply that dolphins cannot minimize the impact of human-made noise, even by adjusting their own vocal behavior.

In collaboration with international colleagues, the scientists equipped two trained and highly motivated bottlenose dolphins at DRC with suction cup-attached tags, allowing them to record the dolphins’ vocalizations while the dolphins participated in a cooperative task. During the task, the dolphins had to work together to both press their own underwater buttons within one second of each other while exposed to increasing levels of noise.

The dolphins produced louder and longer whistles to compensate for the increasing noise levels but were still less successful as the noise got louder. 

Lead author Sørensen, from Bristol’s School of Biological Sciences, said, “For years we have known that animals can attempt to compensate for increased noise in their environment by adjusting their vocal behavior. Our work shows that these adjustments are not necessarily sufficient to overcome the negative impacts of noise on communication between animals working together.”

Bristol’s Stephanie King, senior author, added, “It also shows us that dolphins can flexibly modify their vocalizations in an attempt to continue cooperating with their partner, revealing that this species is capable of actively coordinated collaboration.”

Cooperation is common in animal societies, and many species use sounds that may help coordinate cooperative actions, but using sound also makes them susceptible to disturbance from human-made noise pollution.

“Working with our colleagues at the Dolphin Research Center in Florida, we had a unique opportunity to study the negative effects of noise on cooperative behavior in a controlled setting, something that is almost impossible to do in the wild. Our findings clearly highlight the need to account for how noise affects group tasks in wild animals,” Sørensen noted. 

This study was funded by the Branco Weiss Fellowship – Society in Science and a postgraduate grant from Bristol’s School of Biological Sciences. Find the full text of the paper by using this reference: “Anthropogenic noise impairs cooperation in bottlenose dolphins,” Pernille M. Sørensen, Abigail Haddock, Emily Guarino, Kelly Jaakkola, Christina McMullen, Frants H. Jensen, Peter L. Tyack and Stephanie L. King in Current Biology.