Bottlenose dolphins are talking to each other using a dialect that could be unique to Wales, claim scientists.
Bottlenose dolphins in Cardigan Bay were studied
The whistles of dolphins in Cardigan Bay are different to those living off the Irish coast, a study has found.
Ronan Hickey analysed 1,882 whistles for his masters degree in marine mammal science at University of Wales, Bangor.
Dolphins produce a variety of "vocalisations" including clicks, whistles, barks, and groans to navigate and communicate with each other.
Mr Hickey examined the sounds made by dolphins on both the Welsh and Irish sides of the coast.
He worked with Shannon Dolphin and Wildlife Foundation (SDWF), whose Simon Berrow said: "Whistles are important to dolphin communities and individuals for recognition purposes.
"Calves are thought to learn whistles off their mothers, and therefore that could mean whistles are evolving.
"We would like to do more research because this was a one-off analysis.
"But we've found there's a difference in their (the dolphins) repertoire."
Mr Berrow said sound was very important to dolphins as visibility underwater was very poor.
Mr Berrow said each was thought to have its own distinctive signature whistle, which others can recognise.
Simon Hartley of Cardigan Bay Marine Wildlife Centre, said: "You would expect it - huge studies have been done on killer whales and they have different local dialects, so it doesn't surprise me."
About 240 bottlenose dolphins are thought to use Cardigan Bay.