'Lonely' Bottlenose Dolphin Stuns Scientists by Mimicking Group Chatter, Learn He Was Talking To Himself

Researchers have captured emotional footage of a solitary dolphin talking to himself in the Baltic Sea. The video features a bottlenose dolphin doing three kinds of whistles with nobody around them, Indy100 reported. Researchers were moved by the visual because dolphins are known to be social beings. Seeing a mammal supposedly struggle so much with loneliness, that he began talking to themselves, was a hard reality to witness.

The footage was captured by  Olga Filatova, a cetacean biologist at the University of Southern Denmark in 2019, Live Science reported. The dolphin in focus was a mammal known as Delle by locals. At that time, Delle was swimming mostly around Svendborgsund channel, south of Funen Island, Denmark. This area is not where bottlenose dolphins usually visit or live, and therefore Delle was all alone there.

The recording devices were placed around the Svendborgsund channel by researchers to understand the changes taking place in harbor porpoises due to the presence of the solitary dolphin, Live Science reported. The gathered data stunned them, as they could hear Delle making different kinds of voices.  

"Out of curiosity, I decided to add a recorder that captures actual sounds," Filatova said. "I thought we might pick up a few distant whistles or something along those lines. I certainly didn't anticipate recording thousands of different sounds."

The team observed Delle from December 8, 2022, to February 14, 2023, and detected 10,833 sounds, many of which they believed were related to communication. Among the captured sounds, there were 2,291 whistles, 2,288 burst-pulses — a rapid series of clicks sometimes associated with aggression — 5,487 low-frequency tonal sounds, and 767 percussive sounds.

According to researchers, the three whistles produced by Delle were so distinct, that they could have easily been confused as coming from three different dolphins.

"Bottlenose dolphins have what are known as signature whistles, believed to be unique to each individual, much 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 was engaged in various social interactions."

Researchers were not expecting that they would capture so many conversational sounds, especially at a place where Delle was all alone. "These sounds are traditionally considered communicative, meaning there should be at least two dolphins 'talking' to each other. But Delle was completely alone," Filatova said.

Other theories that researchers have presented regarding the unique phenomenon, is that Delle is calling for others of his kind, Live Science reported. Filatova is not on board with this suggestion. "Though this seems unlikely," she said. "He had already spent three years in the area and would likely know by now that no other dolphins are present."