The dolphins mules (Tursiops truncatus) are social animals that usually live in packs. But in September 2019, a lone dolphin, known as Delle to locals, began hanging around the Svendborgsund Channel, south of the Funen Island, Denmark. This area is outside the usual range of bottlenose dolphins and no other dolphins were seen nearby.
Intrigued, a group of scientists set up underwater recording devices to see how the solitary dolphin’s presence affected the harbor porpoises. But they were surprised when they heard Delle ‘speak’, despite being alone. Now, they have published a study that argues that you could do it to combat your loneliness.
As stated Live Sciencethe main author Olga Filatovaa cetacean biologist at the University of Southern Denmark, said: “Out of curiosity, I decided to add a recorder that captures real sounds.”
“I thought we might catch some distant whistles or something. Certainly I didn’t anticipate recording thousands of different sounds“adds the marine biologist.
For 69 days, between December 8, 2022 and February 14, 2023, researchers detected 10,833 soundsincluding several usually related to communication.
Among them, 2,291 whistles, 2,288 explosive pulses (a rapid series of clicks sometimes associated with aggression), 5,487 low-frequency tonal sounds, and 767 percussive sounds. The findings were published in a new study Oct. 31 in the journal Bioacoustics.
Among these noises, the dolphin emitted three distinctive whistles. “Bottlenose dolphins have what is known as characteristic whistleswhich are believed to be unique to each individual, like a name,” Filatova said.
“If we hadn’t known that Delle was alone, we might have concluded that a group of at least three dolphins participated in various social interactions,” adds the scientist.
Filatova did not expect to hear any vocalizations, much less noises associated with communication. “These sounds are traditionally considered communicative, meaning there should be at least two dolphins ‘talking’ to each other. But Delle was all alone“, said.
At first, scientists wondered if the dolphin might be trying to communicate with a local paddle boarder, but they also recorded the sounds during the night. “There were definitely no humans in the water”Filatova said.
It remains a mystery why the lone dolphin talked so much. He could have been talking to himself or they could have been involuntary sounds brought on by a certain emotion, “much like how we laugh sometimes when we read something funnyeven if there is no one else around to hear us,” Filatova said.
Another theory is that he was screaming with his hope to attract the attention of other nearby dolphins. “Although this seems unlikely,” he said. “He had already spent three years in the area and would probably already know that there are no other dolphins present,” Filatova maintains.
Researchers do not usually record the sounds made by solitary dolphins. “They are considered outcasts, rarities, and no one really expects them to make sounds worth documenting,” Filatova concluded.