We’ve long compared dolphin social intelligence to our own, but new research suggests their memories may be more sophisticated than we imagined.
For the last 60-70 years, scientists have been uncovering the remarkable social intelligence of dolphins, following the pioneering work by neurophysiologist Dr. John C. Lilly, who first recorded and published dolphins’ complex whistles and clicks in 1961. Since then, many studies have come out further validating their complex communication skills (like the ability to process complex, artificial syntactic language) and self-awareness (through the mirror-test.)
Now, a recent study published on June 1 in Proceedings of the National Academy of Sciences has found that female Indo-Pacific bottlenose dolphins can identify males based on their unique sounds. Like a vocal name tag, the females use their memories to remember which males were pushy and aggressive in past mating seasons to minimize mating risk.
Listen to the signature whistle of a male Indo-Pacific Bottlenose dolphin here.
The Study
To test how the female Indo-Pacific Bottlenose dolphins were recognizing and remembering the males, researchers broadcast the signature whistles of known males while observing the females’ behavior above using drones. They found the females did not respond equally.
“We combined these experiments with long-term behavioral data to examine how female reproductive state, sociability, and interaction history shaped their responses. Females who were reproductively available showed a significantly stronger aversive response to the identity signals of males who coerced females at higher rates, suggesting that females track male behavior across time and use individual vocal labels to guide reproductive decision-making based on their experience of individual male behavior.”
— Female dolphins use individual vocal labels to track coercive males (Bouchard et al., 2026)
Being highly social, Indo-Pacific bottlenoses can be found most commonly in groups of 5-15 individuals, with the occasional aggregate of over 100. These groups are more complex than just family trees and are often sexually segregated. While mating occurs year round, peaks often occur in May-June, where mature males will often form a strongly bonded alliance with at least 3-4 other males to compete for access to females.
Two Indo-Pacific Bottlenose dolphins surfacing off the coast of Perth, Australia, courtesy of Lara Rodrigues (@lararodriguesl_)
In Shark Bay, Australia, where the study took place, these male-dominated alliances can cooperatively herd or closely guard females for extended periods, limiting their opportunities to interact with other males. While not all males display these behaviors, coercive mating strategies have been well documented within this population.
In such a socially complex environment, remembering previous interactions with specific individuals can have important consequences. If a female can recognize not only who is calling, but also how that individual behaved in the past, she may be able to navigate future encounters and reproductive success.
The Bigger Picture
For decades, much of dolphin social and cognition research has focused on whether dolphins possess abilities such as self-awareness, vocal learning, or symbolic communication. However, increasingly, researchers are now beginning to shift from asking whether dolphins have these capabilities to how they use them in their daily lives and relationships. This study is a great example of not only asking whether dolphins can recognize each other’s signature whistles, but also how those whistles function and the implications of such.
The research also highlights the importance of long-term field studies. Because scientists have followed the Shark Bay bottlenose dolphin population for decades, they were able to combine years of behavioral observations with modern technologies like drone observation and acoustic playback. Together, these approaches are revealing dolphin characteristics that would be impossible to detect through short-term studies alone.
Read the full study from the Proceedings of the National Academy of Sciences: https://www.pnas.org/doi/10.1073/pnas.2531602123
Credit
Thumbnail & Hero: Two curious Indo-Pacific Bottlenose dolphins captured underwater in the Indian Ocean by Pavlos Evangelidis (@wantok.photos)