Female dolphins recognise ‘dangerous’ males by their voices
Female dolphins may be able to recognise ‘dangerous’ males by their voices and keep their distance from them in advance. This is the conclusion reached by scientists studying Indo-Pacific bottlenose dolphins in Shark Bay off the coast of Western Australia.
We’re not talking about human names, but about distinctive individual whistles. Every dolphin has its own recognisable signal — a sort of acoustic tag. This allows other dolphins to identify exactly who is nearby.
In a new study, females who may have been ready to breed swam further away from the calls of males who had previously behaved more aggressively and tried to restrain the females during mating interactions.
The study has been published in the *Proceedings of the National Academy of Sciences*.
Details
Shark Bay dolphins have a complex social life. Males often form alliances and may jointly pursue or restrain a female during the mating season. Sometimes this behaviour can be aggressive: males may restrict a female’s movement, bite her, push her with their bodies or strike her with their tails.
The researchers wanted to understand whether females could recognise such males in advance and avoid unwanted contact.
To do this, the researchers used recordings of the individual whistles of 11 adult males. They then played these sounds through an underwater loudspeaker to 17 adult females in the wild. A total of 34 such acoustic tests were carried out. The females’ reactions were filmed using a drone to clearly see whether the animal swam away from the sound source.
It turned out that the reaction did not depend simply on the familiarity of the sound. Females that were reproductively receptive were more likely to avoid the whistles of males who had a history of coercive behaviour towards females.
Put simply, a female would hear the ‘voice’ of a specific male — and, if that male had a bad reputation, she was more likely to try to get as far away as possible.
Why these aren’t quite ‘names’
Dolphins have what are known as ‘signature whistles’ – individual whistles. These are often compared to names because they help to recognise specific individuals.
But these are not names in the human sense. They are unique acoustic signals that allow other dolphins to identify who is making the call.
That is precisely why the word ‘name’ is best put in quotation marks. It is more accurate to write: female dolphins recognise males by their individual whistles.
Why this is important
Research shows that female dolphins do not simply react passively to the behaviour of males. They can use social memory: remembering which males have behaved coercively, and altering their own behaviour when they hear their calls.
This points to the complex social lives of dolphins. They can keep track not only of ‘who’s who’, but also of how specific individuals have behaved in the past.
However, the researchers do not claim that dolphins compile ‘blacklists’ or judge males morally, as humans do. The conclusion is a more cautious one: females probably use individual acoustic signatures and past experience to reduce the risk of unpleasant mating encounters.
Background
The dolphin population in Shark Bay has been studied for decades. This is one of the world’s best-known groups of wild dolphins: scientists are very familiar with many of the animals, their relationships, ages, behaviour and individual whistles.
It was previously known that male dolphins use such whistles to recognise allies and maintain social bonds. The new study shows that females may also use these acoustic signatures – but to assess the risk posed by males.
This is important for understanding the animals’ mating behaviour. Even in species where males can be aggressive and persistent, females find ways to avoid unwanted contact and maintain a safer distance.
Source
Study: Alice Bouchard et al., “Female dolphins use individual vocal labels to track coercive males”, Proceedings of the National Academy of Sciences, 2026.