A team of marine biologists at the University of Southern Denmark has recently discovered a solitary bottlenose dolphin (Tursiops truncatus) living in the Baltic Sea.
What’s particularly remarkable is that it appears to be “talking” to itself. In a study published in the journal Bioacoustics, the research team analyzed thousands of sounds emitted by this lonely dolphin and uncovered fascinating insights about this solitary creature.
Journey to an Unfamiliar Sea
Five years ago, residents living along the Svendborgsund canal in the Baltic Sea, Denmark, were surprised by the appearance of a solitary male bottlenose dolphin. It seemed to have chosen this canal as its home. This is a rare discovery, as bottlenose dolphins typically live in pods and are not commonly found in this area.
The local people quickly named the dolphin Delle. Delle’s presence attracted the attention of scientists, who were curious as to why a dolphin would choose to live alone in an unfamiliar place. They noted that Delle didn’t seem to socialize with the local harbor dolphins, a smaller species that typically inhabits the area.
Dolphin Delle emits sounds often associated with aggressive behavior in dolphins. (Illustrative image).
Sounds from Solitude
To learn more about Delle, researchers deployed underwater recording devices to see how the presence of this solitary dolphin affected the local harbor dolphins. They were shocked to hear Delle produce such a wide range of sounds. The lead author, Olga Filatova, a dolphin biologist at the University of Southern Denmark, communicated with Live Science via email: “Out of curiosity, I decided to add a recorder to capture the actual sounds. I thought we might get a few distant whistles or something similar. I certainly didn’t anticipate recording thousands of different sounds.”
The discovery astonished the research team: over the course of 69 days, from December 8, 2022, to February 14, 2023, they recorded 10,833 distinct sounds produced by Delle.
Through analysis, the team found that Delle emitted a variety of sounds, ranging from clicks and whistles to noises typically associated with aggressive behavior in dolphins. Notably, among these sounds were those commonly used for communication between dolphins, indicating that Delle might be conversing with itself. Delle also produced low-frequency sounds and rhythmic claps, believed to aid in spatial orientation and foraging.
Theories on the “Conversation”
Initially, scientists wondered if the dolphin was trying to communicate with a local kayaker, recording sounds at night to see if any people were around.
Thea Taylor, executive director of the Sussex Dolphin Project, who was not involved in the study, shared with Live Science via email: “Dolphins are very vocal animals, so it’s not surprising that this individual continues to make sounds even when alone.” She added, “Dolphins rely on sound for essential activities like hunting and sensing their environment,” and they also use sound for long-distance communication.
Interestingly, Delle continued to produce these sounds even when no humans were nearby. This suggests that the dolphin was not trying to communicate with people but perhaps was comforting itself.
The research team proposed several emotional hypotheses: “It’s possible that Delle is expressing spontaneous emotions, similar to how humans laugh when reminiscing about something while alone. Or perhaps it simply feels lonely, and ‘talking’ to itself is a way to distract from that solitude.”
The story of Delle is not just a scientific discovery; it serves as a gentle reminder of loneliness, a feeling that not only humans, but perhaps animals too, experience. The image of Delle alone in the Baltic Sea, without friends or companions, prompts us to reflect on our responsibility to protect and empathize with the natural world.
This small dolphin, with its voice, seems to narrate a sad tale of solitary existence, yet it also stands as a testament to the resilience and survival instinct in a challenging world.
