Thursday, September 30, 2010

Dolphin species try common language

Have you ever thought how Dolphins communicate with each other? If yes is the answer for this, it would be probably by their sounds. But do you think that dolphins all around the world sound same? No Dolphins produces different sounds. When two dolphin species come together, they try to find a common language, preface research suggests.

Bottlenose and Guyana dolphins, two faintly related species, often come together to socialize in waters off the coast of Costa Rica. Both species make unique sounds, but when they gather, they change the way they communicate, and begin using a middle language. That raises the possibility the two species are communicating in some way.

It is not yet clear exactly what is taking place between the two dolphin species, but it is the first proof that the animals modify their communications in the presence of other species, not just other dolphins of their own kind.
Biologist Dr Laura May-Collado of the University of Puerto Rico in San Juan made the discovery studying dolphins swimming in the Gandoca-Manzanillo Wildlife Refuge of the southern Caribbean coast of Costa Rica. Bottlenose dolphins (Tursiops truncatus) are larger, measuring up to 3.8m long, with a long dorsal fin. Guyana dolphins (Sotalia guianensis) are much smaller, measuring 2.1m long, and have a smaller dorsal fin and longer snout, known as a rostrum. Both species swim in groups made up of their own kind.

When bottlenose dolphins swim together, they emit longer, lower frequency calls that are modulated. In contrast, Guyana dolphins typically communicate using higher frequency whistles that have their own particular structure.

But often, the two species swim together in one group. These communications are usually aggressive, as the larger bottlenose dolphins pester the smaller Guyana dolphins.
When the two dolphins meet, they produce quite dissimilar calls, Dr May-Collado has discovered.
Critically, calls emitted during these multi-species encounters are of a middle frequency and duration. In other words, the dolphins start communicating in a style that is somewhere between those of the two separate species. This may be weird news but it was a surprise when we came to know about this. Scientists were expecting both species to accentuate, perhaps embellish, their species-specific signals. Instead the signals recorded during these encounters became more homogenous. This was a very thrilling discovery.

As yet, Dr May-Collado cannot be sure if both species are changing the way they communicate, or whether it is one species attempting to call more like the other. That is because her sound equipment could only record the total calls produced by mixed species groups of dolphins, and could not separate out sounds made by individuals. This limits how much the scientist can say about how much they are communicating with each other.

However, dolphins are known to have an unusual ability to change their calls when 'talking' to other individuals, or to ensure they are heard over the din of background noise pollution.
So it should’nt be surprise that they can modify their signals to mimic, and even possibly communicate with other species. Particularly when their home ranges force them to interact on a daily basis, which is the case of this study. It is also unclear whether the two species are simply learning to communicate using a common language, or whether the Guyana dolphins alone are making the new sounds due to stress. It could even be that the Guyana dolphins are attempting to emit threatening sounds in the language of the intruder in a bid to make the bottlenose dolphins stop.