Whistle! Chirp! Squeak! What does it mean?

Bottlenose dolphins each have a unique call, known as a signature whistle, which allows them to communicate their identity, location, and maybe even how they are feeling. Other high-pitched chirps, squeaks, and trills, called nonsignature whistles, are less understood and will be the research focus of WHOI biologist Laela Sayigh this spring, supported by a $350,000 grant from the Avatar Alliance Foundation.

“We hope to learn who is saying what and why,” said Sayigh, lead researcher on the Florida-based project. “Right now, we have no idea how these whistles function. But we are considering the possibility that they could work like human words or phrases with specific meanings to dolphins.”

In collaboration with the Sarasota Dolphin Research Program, Sayigh began studying the whistles of Sarasota Bay’s dolphins in the mid-1980s as the basis of her MIT-WHOI doctoral dissertation. By recording known individuals during brief catch-and-release health assessments, the researchers have built a catalog of signature whistles of most of the 170 dolphin residents in the community.

Dolphins in the study group “tend to make a lot of signature whistles, so they’re usually pretty easy for us to identify,” Sayigh said. “But we also hear other whistle types whose communicative purpose we’re just beginning to understand.”

Pinpointing these whistle types is ongoing, and so far, the researchers have identified 20, two of which were produced by at least 25 different individuals. Using playbacks of sound recordings and noting the dolphins’ responses, they found that one widely shared nonsignature whistle consistently elicited avoidance responses in the mammals, suggesting that it functioned as an alarm or warning. They found that another nonsignature whistle may be a “query” type of whistle, produced when the dolphins hear something unexpected or unfamiliar.

“[This work] could serve as a kind of ‘Rosetta Stone’ for understanding how dolphins are communicating as never before.”
—Peter de Menocal, WHOI’s president and director

Dolphins can be “quite chatty,” Sayigh said, depending on their group size and activity. Understanding dolphin communication offers a chance to learn more about the dynamics of our coastal neighbors’ interactions and the natural as well as the human-induced factors that impact them, such as ocean noise pollution from ships.

“They have distinctive personalities. Some are very talkative while others are not,” she said. “It also depends on their age and what they’re doing. Younger animals, in groups, tend to be vocal. But if alone, they are not going to be whistling just to themselves.”

The Avatar Alliance Foundation grant will contribute to additional playback recording trials of these and other nonsignature whistles. It will also support the hiring of a research assistant to help with call identification and classification as well as supporting the assistant to spend a week on field work, expected to begin in May, 2025.

The nonprofit foundation, based in New York City, has given $2.6 million for other WHOI research over seven years in addition to donating the Deepsea Challenger submersible, valued at $32 million.

“The Avatar Alliance Foundation has been a visionary partner to WHOI, providing not just generous financial support, but also amazing connections to other advocates for ocean science and a powerful understanding of how to connect with broad audiences,” said Peter de Menocal, WHOI’s president and director.

The foundation has contributed to the cost of displaying the Deepsea Challenger at museums and other venues worldwide. It has provided funding for WHOI’s efforts in communications and marketing, including support for the U.N.’s climate change conference COP28 Ocean Pavilion in Dubai, where the foundation served as a lead sponsor.

De Menocal added that Sayigh’s effort to link shared whistles to consistent dolphin behaviors “could serve as a kind of ‘Rosetta Stone’ for understanding how dolphins are communicating as never before.”