Why this lonely dolphin in the Baltic Sea can’t stop talking to itself

It’s 2019 and bottlenose dolphin number 1022, born in Scottish waters in 2007, is suddenly spotted completely alone, hundreds of miles from his home before finally landing in Denmark, some 500 miles (800 km) away on the other side of the North Sea.

Get to know “Delle”, as he was called by the Danish locals. A lone bottlenose dolphin whose actually The name introduced years ago by Scottish researchers is Yoda, No. 1022, identified by his unique dorsal fin markings. He was part of the Moray Firth group of dolphins named Star Wars, which also included his mother Chewbacca and his siblings Skywalker and Kenobi. However, we will call him by his new name, Delle.

Delle gave us a rare insight into the secrets of dolphin communication.

Delle set up his home base in Svendborgsund – a busy waterway outside the Danish island of Funen – far, far away from the usual haunts for bottlenose dolphins. Over the course of three years, he has become something of a local celebrity, delighting onlookers with his flying antics and confusing scientists with his vocalizations.

Researchers lowered a microphone into the water from December 2022 to February 2023 and recorded a total of 10,833 sounds from Delle. They had originally expected Delle to keep his chatter to a minimum, just echolocating for food and the like. Instead of silence, Delle was a one-dolphin band that produced a wide range of sounds. And it wasn’t just about feeding or navigating. He “spoke” to anyone who would listen, even if it was just himself.

Dolphins are incredibly intelligent and social mammals that typically live in groups. Dolphins’ communication systems are considered to be very complex and even have parallels to human communication. “Signature whistles” are unique to each dolphin, just as names are unique to a person (I wonder how many dolphins are named “James”?).

Dolphins identify themselves with a distinctive whistle and will even mimic another dolphin’s signature whistle to interact with a particular member of the group. “Hey James, it’s James! Do you want to celebrate? I have some sardines!”

Jesper Stig Andersen

So what does he say?

First of all, Delle made three unique, signature whistles, which is strange. Researchers believe that Delle’s behavior is affected by being isolated and without social interaction for so long. Maybe he does it to amuse himself, or he calls out the “names” of the dolphins he used to spend time with. It could simply be a coping mechanism to get him through the day. The reasons for this are all speculative, as this type of solo dolphin phenomenon is not commonly observed. Maybe he has split personality disorder? Traditionally, dolphins are thought to have a one-whistle-per-dolphin system, but Delle overturned that theory with his repertoire of triple whistles.

Delle isn’t just content with whistles. He adds something called biphonic sounds – that is, you make two sounds at the same time. We’re not sure why dolphins do this, but it could be that it makes their communication with each other even more complex. Some people can do it. We call it overtone or throat singing. Although this is rare in dolphins, it has been observed before and is therefore not entirely unique.

Delle, on the other hand, is full of biphonic sounds, including combinations of whistles, low-frequency calls, and burst-pulse sounds… since there are no conspecifics anywhere nearby, Delle may simply be sticking out his two phrases from the phonic lips (the dolphin version of the vocal cords) and just experiment with his vocal range. Admittedly, bottlenose dolphins are known to often communicate with others several miles away.

Among its most common sounds were rhythmic low-frequency sounds known as “swallowing.” Researchers have linked swallowing to everything from food intake (no pun intended) to social excitability. Delle apparently did it for no other reason than to hear himself, much like when you, dear reader, sing in the shower when no one is home.

Wikipedia – CC BY-SA 4.0

Scientists have a few theories as to why Delle is causing a stir:

Delle could just be sad and lonely and the sounds could be intentional or unintentional expressions of emotion. Most animals express basic emotions. For example, if your four-legged friend cries with joy when you come home or with sadness when you leave.

Or Delle sings “the song of his people” in the hope of finding his fellows. Even though he had spent the last three years in the same place with no other whales in sight, you would think that he would have realized that he simply wasn’t invited to the party.

Another suggestion – since many of his sounds came in rhythmic bursts and often during his signature jumps – maybe he was just in the mood for some funky beats to get his dancing going.

Delle’s rant raises as many questions as it answers. Is it a sign of emotional complexity? Does he practice his sounds like a dolphin musician? Or does it simply reflect his natural need for social interaction? In the end, Delle (or bottlenose dolphins in general) may not be all that different from us. We all have a desire to be heard, even when no one is listening.

At least Delle hasn’t started wearing tuna hats like some other dolphins we know it.

Source: Taylor and Francis