Human fascination with bottlenose dolphins goes back thousands of years, at least as early as Greek mythology.
But it wasn’t until the 1960s that methodical research into dolphin communication began. Scientists like John Lilly and the husband-and-wife team of Melba and David Caldwell tried various experiments to decipher the sounds dolphins can make.
The Caldwells figured out a way to record isolated animals in human care. They discovered that each individual dolphin communicated mostly with one unique whistle, which they called the “signature whistle.” Researchers now know that these whistles convey identities much like human names do. Dolphins use them to stay in touch with each other in their murky habitat, where vision is limited. It’s like announcing “I’m over here!” when someone can’t see you.
This discovery is foundational to my own research. I’ve been studying communication in wild dolphins since the mid-1980s, when I joined my mentor Peter Tyack in documenting signature whistles in wild dolphins for the first time. Our team’s research focused on a resident community of free-ranging bottlenose dolphins in waters near Sarasota, Florida, where I continue to work today.
This collaborative study, led by Randall Wells of Brookfield Zoo Chicago’s Sarasota Dolphin Research Program, involves numerous researchers from a variety of institutions, who study different aspects of dolphin biology, health, ecology and behavior. Begun in 1970, this is the longest-running research project on a population of wild cetaceans – whales, dolphins and porpoises – in the world.
Each dolphin has distinctive markings on its dorsal fin. Experienced researchers can sometimes identify them by sight in the field, and they photograph them to confirm their identity in the lab.
Photo by Brookfield Zoo Chicago’s Sarasota Dolphin Research Program, taken under NMFS MMPA Scientific Research Permit
Recording and observing
Researchers know the age, sex and maternal relatedness of almost all of the approximately 170 dolphins in the Sarasota community. This depth of knowledge provides an unprecedented opportunity to study communication in a wild cetacean species.
The dolphins in the Sarasota project are periodically subject to brief catch-and-release health assessments, during which researchers, including me, briefly handle individual dolphins.
Our team attaches suction-cup hydrophones directly onto each dolphin’s melon – that is, its forehead. We then record the dolphins continuously throughout the health assessments, taking notes on who is being recorded when, and what is happening at the time.
This is how my colleagues and I were able to confirm that wild dolphins, like captive animals, produced large numbers of individually distinctive signature whistles when briefly isolated from other dolphins. Through observations and recordings of known free-swimming dolphins, we were further able to…
