Diving into the Depths of Dolphin Communication

An article written for an online course on Animal Behaviour I am doing at the moment: 


“Hello”, “Alright Mate”, “Good to see you”; all ways in which we as humans often greet each other.  Depending upon how well we know someone, who they are and of course the situations we are in, our vocalisations vary.  As the foundation of human language, learnt vocalisation comes so naturally to us that it is sometimes peculiar to think that it’s not a common occurrence within the animal kingdom.


The majority of animal species use innate vocalisation in order to convey alerts of danger and other happenings. This means it is ‘genetic’behaviour which accompanies being a member of that particular animal group. A meerkat, for example, knows to be aware of the danger of a snake and to alert others of it’s presence; it does not need to first encounter one to know that it poses a significant threat .There are some species, however, who exhibit behavioural traits that have been shown to have been learnt by a particular animal with the bottle nosed dolphin being an ideal example.


In a recent paper published in PNAS, King and Janik focused upon dolphins to examine how the concept of a ‘signature whistle’is exhibited and it’s uses within their lives. A ‘signature whistle’is an aspect of communication created by an individual as a juvenile made up of various vocalisations they encounter. Once formed it is then used as a way of informing others who they are and as a greeting when meeting new individuals becoming a vital aspect of their vocalisation repertoire.With this in mind, it could be thought of as perhaps a human like vocalisation almost akin to they way we  greet others as individuals with their own names.


In order test whether the ‘signature whistle’acts in this way, King and Janik focused upon wild bottle nosed dolphins off the East coast of Scotland.  Their whistles were recorded before being  copied and played back to them or they were played unfamiliar and familiar dolphins’vocalisations. From June to August 2001 and May to September 2010, recordings were taken at a depth of 2 metres before being analysed and recorded as synthetic vocalisations. One playback was then played back to each dolphin pod with the boat engine off and when the animals were either socialising or exhibiting non polarised behaviour. This was perhaps due to the fact that as with any species, the likelihood of responding to being called is somewhat diminished when an individual is focused upon something else.


The responses to the stimuli revealed that the signature whistle could indeed be classified as a way of dolphins greeting specific individuals. Out of 12 dolphins, 8 responded with the same vocal pattern upon hearing their own call whereas only 2 responded to the familiar pattern and there were 0 responses to the unfamiliar calls. This suggests that, much like human patterns of behaviour, the dolphins responded when they were addressed or another individual recognised the call of a dolphin it knew and so responded to it.


King and Janik’s results, however, are not unique as such behaviour has been observed in birds who also have exhibited copying certain sounds to address each other.  Nevertheless, the results are certain to raise the question of why individual dolphins produce a ‘signature whistle’. It could be that not unlike other mammals, they are trying to contact a particular dolphin or maintain a level of understanding within the group structure. This is something which can clearly be observed amongst people indicating a succinct similarity between both species. Either way, it is likely to be a question at the forefront of many behaviourist’s minds and only further exploration of the secretive life of cetaceans can reveal the answer.  


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