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Irish scientists monitoring dolphins living in a river estuary in the southwest of the country believe they may have developed a unique dialect to communicate with each other.
The Shannon Dolphin and Wildlife Foundation (SDWF) has been studying a group of up to 120 bottle-nose dolphins in the River Shannon using vocalizations collected on a computer in a cow shed near the River Shannon.
As part of a research project, student Ronan Hickey digitized and analyzed a total of 1,882 whistles from the Irish dolphins and those from the Welsh dolphins on a computer and separated them into six fundamental whistle types and 32 different categories. Of the categories, he found most were used by both sets of dolphins but eight were only heard from the Irish dolphins.
"We are building up a catalogue of the different whistle types they use and trying to associate them with behavior like foraging, resting, socializing and the communications of groups with calves," project leader Simon Berrow said. "Essentially we are building up what is like a dictionary of words they use or sounds they make."
Berrow, a marine biologist, said the dolphins' clicks are used to find their way around and locate prey. The whistles are communications. "They do a whole range of other sounds like barks, groans and a kind of gunshot," he said. "The gunshot is an intense pulse of sound. Sperm whales use it to stun their prey."
"When I first heard it I was surprised as I thought sperm whales were the only species who used it. We can speculate the dolphins are using it for the same reason as the sperm whales," Berrow said.
References in local legend indicate there have been dolphins in the Shannon estuary for generations and they may even have been resident there as far back as the 6th century.
They are regularly seen by passengers on the Shannon ferry and an estimated 25,000 tourists every year take special sightseeing tours on local boats to visit them.

单选题 The difference in eating habits between the bottle-nose dolphins and the sperm whales interested the SDWF scientists.

单选题 Ronan Hickey analyzed almost 2000 different dialects of the bottle-nose dolphins.

单选题 Of the 32 categories, eight were produced only by the Irish dolphins.

单选题 Whistles could also be used to communicate between adult dolphins and baby dolphins,

单选题 Sperm whales can produce stronger ultrasonic waves to kill their prey than dolphins.

单选题 As early as the 6th century, Irish fishermen started raising dolphins in the Shannon estuary.

单选题 Irish dolphins attract tourists and over 25,000 people come to see them every year.