By Christa Lesté-Lasserre
The bottlenose dolphins are very social.
Brad Leue is in the picture.
Common bottlenose dolphins change their volume throughout their whistles as a way to communicate more than just their identity.
A signature whistle is a unique combination of sound frequencies held for specific lengths of time to create a special call that each dolphin uses to identify itself. The signature whistles of dolphins are the same throughout their lifetimes. A new study has shown that the cetaceans vary the volume of their whistles, and that the pattern changes with every call.
Brittany Jones says that it seems like non-word communication like putting emphasis in a certain area or how we fade out and fade in so we know when it's each other's turn to talk is what we use.
The findings suggest that dolphins might be using frequencies to communicate with each other.
Scientists have been studying the whistles of bottlenose dolphins for 60 years. Underwater animals are moving in different directions and it's difficult to get a good picture of the differences in amplitude.
Improved technology in underwater microphones, called hydrophones, along with more advanced sound analysis equipment and a more controlled recording environment have made it possible to study dolphins whistle amplitudes with greater accuracy.
Dolphins are trapping fish in mud rings in the Caribbean.
The team used this technology to record the signature whistles of eight adult dolphins living in natural seawater enclosures in the San Diego Bay as part of the US Navy Marine Mammal Program.
The dolphins all had their signature whistles that had Frequency Patterns. The volume patterns of the dolphins changed considerably.
When they were whistling at a lower Frequency, they increased their volume. There were no clear patterns across dolphins or within the whistles from the same dolphin. They made parts of their call louder and softer.
Jones initially wondered if the patterns were random after she was surprised by how variable they were. She says that if the signature is constant, it makes it hard to communicate different things. Maybe this is a new avenue that allows dolphins to code additional information.
We can't imagine what the volume patterns would mean to other dolphins, but there are plenty of things these highly social creatures might want to say.
Jones says that they wouldn't want to be telling each other. The sky is the limit in terms of what dolphins might communicate about.
The journal has a reference to Behavioural Processes.
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