Dolphins Can Recognize Whistles Of Companions Despite Being Separated For Over 15 Years

We know for a fact that dolphins recognize each other through their whistles, but a recent study conducted by Jason Bruck revealed that dolphins have one of the longest, if not the longest, memory among any animal beside humans.

Bruck, a researcher from the University Of St. Andrews in Scotland, conducted a study to determine whether animals could remember their friends after several decades of being away from each other.

The signature whistles of dolphins played the biggest role in the study. Bruck studied 43 dolphins that were put together in a certain breeding program facility almost 20 years ago. The researcher collected data of dolphins that were roommates before to determine whether they can still recognize the signature whistles of each other.

Bruck collected recorded sounds of whistles of dolphins. He initially played recorded whistles of dolphins that do not belong in the sample group. The dolphin did not respond to the sound, but when whistles of dolphins included in the sample group were played, it rushed towards the speaker as if it was excited to meet a long-lost friend.

A female dolphin named Bailey, one of the dolphins used in the study, responded to the signature whistle of another female dolphin named Allie. Bailey recognized the whistle of Allie despite being away from each other for 20 years and six months. Bailey and Allie were housed at the Dolphin Connection in Florida Keys before when they were just 4 and 2 years of age, respectively.

"As I have shown, that dolphins were capable of remembering each other's whistles for 15 or more years, up to 20, with no decay. Duration of association did not affect recognition, meaning long periods of association were not required for long-term recognition," wrote Bruck in his paper.

"Sex (both respondent and caller) and kinship status did not affect recognition. This is expected given that both males and females inhabit socially complex groups, and both kin and non-kin would need to be remembered in networks of at least 60-70 individuals with whom they cooperatively hunt and engage in predation defense."

Bruck conducted the study in zoos and aquariums, but he is also confident that these traits also exist in free-living dolphins in the wild because they all possess similar social complex traits.