Bermuda dolphin has excellent memory, researcher finds

A Bermuda dolphin has helped researchers prove it’s not only elephants that never forget.

For Bailey – one of the stars at Dockyard’s Dolphin Quest – has helped scientists prove that dolphins have the best memories among non-humans and remember the distinctive calls of former companions more than 20 years later.

Dolphin Quest general manager Christine Mihelcic said: “They are very clever – I don’t know if I would say I was surprised by the results of the research, but there was new information generated as a result of the work.”

Ms Mihelcic was speaking after University of Chicago researcher Dr Jason Bruck investigated dolphins’ recall over a two year period.

Dr Bruck visited Bermuda several times, playing dolphin whistles through underwater loudspeakers and measuring their responses.

And he was amazed when Bailey responded to the call of another dolphin called Allie with whom she had lived when very young in the Florida Keys.

Bailey, who has been in Bermuda for 17 years, recognised Allie’s distinctive whistle, even though the two had last been together more than 20 years ago.

Dr Bruck told the BBC: “When they are familiar with the call, the dolphins are more likely to approach the speakers for longer periods of time.

“They will maintain contact with the speaker – if they are unfamiliar with the call they are more likely to ignore what I am playing. It’s unprecedented in the study of animal behaviour to find memories this long.”

To double-check, he also played recordings of dolphin calls that were the same age and gender – which showed a clear difference in responses.

Ms Mihelcic said Dolphin Quest was regularly approached by researchers who wanted to study their dolphins.

She added: “Research projects go to a committee and determination on whether want to take part is made.”

Dr Bruck visited the island several times between 2009 and 2011 to carry out his work, which has just been published in the prestigious UK-based Proceedings of the Royal Society B, its biological sciences publication.

Ms Mihelcic said: “We were happy to help – it’s one of our core values to support scientific research.”

She added that Dolphin Quest also had an educational supervisor on staff, who visited schools and promoted interest in aquatic science.

She said: “It’s giving back to the community – it’s part and parcel of being responsible members of society.”

The University of Chicago researchers said they believed that the complex social systems were behind the long-term recall because dolphins in the wild may join and leave several groups in their lifetimes.

Dr Bruck said: “It is important for them to recall the calls of dolphins they have had previous encounters with to decide whether or not that’s someone they want to approach when they hear that whistle about a mile out, or whether they want to avoid that individual.

“Having a long term social recognition for the ecological reason can be the difference between an animal having a very negative social interaction and a positive one.”

The study proves that dolphins have memories comparable to humans, chimpanzees and elephants – although there is little scientific evidence that their recall extends outside their immediate family relationships, while dolphins can remember non-relatives as well as family.