Dolphins remember their friends for decades
Dolphins can recognize their old tank mates' whistles after being separated for more than 20 years — the longest social memory ever recorded for a non-human species.
Jason Bruck, who completed his Ph.D. this summer at the University of Chicago, is pictured here working with a dolphin at the Brookfield Zoo near Chicago. His research indicates that dolphins have the longest social memory ever recorded among non-human species.
To establish how well dolphins could remember their former companions, Dr.Jason Bruck working at the University of Chicago collected data from 53 different bottlenose dolphins at six facilities, including Brookfield Zoo near Chicago and Dolphin Quest in Bermuda. The six sites were part of a breeding consortium that has rotated dolphins and kept records on which ones lived together, going back decades.
Over the course of several decades, some of the dolphins were rotated between these six sites so they could breed. Concise records were kept on which dolphins were housed together, which allowed Bruck to investigate whether they could remember former tank mates.
Bruck played recordings of signature whistles to dolphins that had once lived with the animals that made the calls and compared the reactions to whistles made by dolphins who have never met.
Determining whether the dolphins recognized their old companions required a methodical comparison of how they responded to familiar calls versus calls belonging to dolphins they had never met.
This research shows that dolphins have the potential for lifelong memory for each other regardless of relatedness, sex or duration of association.