Bottlenose dolphins appear to remember one another's whistles for up to 2
The Scientist, Kate Yandell, August 8, 2013
full story, phono:
Last month, a study suggested that dolphins use
signature whistles developed during the early months of their lives to call
each other by name. Now, a researcher from the University of Chicago has
demonstrated that bottlenose dolphins can remember the distinctive whistles of
members of their species for up to 20 years, according to a study published
yesterday (August 7) in the
Proceedings of the Royal Society B.
Biologist Jason Bruck collected data on relationships between dolphins that had
been shuffled among six zoos and aquariums in the U.S. and Bermuda. Bruck then
played the dolphins' whistles to one another through underwater speakers.
Dolphins were more likely to respond to the whistles of those they had lived
with in the past than to unfamiliar dolphins, approaching the speakers and
whistling at them. The dolphins responded to the whistles of former tank mates
even when they had been separated for long periods of time. One pair of animals,
Allie and Bailey, had been separated for 20.5 years, according to a University
release, when the researchers played Allie's whistle, Bailey responded.
"We can't tell yet what the upper limit is time-wise, or even if there is one,"
Nature. "We just know it's at least 20 years."
Bruck wrote that the dolphins' whistle memories could help them decide whether
to approach a nearby dolphin to form an alliance, or avoid that dolphin because
it posed a threat.
However, New College of Florida psychology professor Heidi Harley told
The Washington Post that it was unclear whether the dolphins were conjuring
pictures of their former tank mates or simply responding to familiarity. "Is
this really about the dolphins that produce these whistles, or is it just about
the sounds themselves? It's a little hard to disentangle sometimes," she said.