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

It's 2019 and bottlenose dolphin #1022, born in Scottish waters in 2007, is suddenly spotted completely alone, hundreds of miles from his home before ending up in Denmark, some 500 miles (800 km) away across the North Sea.

Meet "Delle," as he was named by the Danish locals. A solitary bottlenose dolphin whose actual name from years ago by Scottish researchers is Yoda, #1022, identified by his unique dorsal fin markings. He was part of the "Moray Firth" pod of Star Wars-named dolphins that included his mother, Chewbacca, and his siblings Skywalker and Kenobi. We'll call him by his new name though, Delle.

Delle has given us a rare glimpse into the mysteries of dolphin communication.

Delle set up home base in Svendborgsund – a busy waterway outside Funen Island, Denmark – far, far from any usual bottlenose dolphin hangouts. Over three years, he's become somewhat of a local celebrity, delighting onlookers with his aerial antics and confusing scientists with his vocalizations.

Researchers lowered a microphone into the water from December 2022 through February of 2023 and recorded a total of 10,833 sounds from Delle. They had initially expected Delle would keep his chatter to a minimum – only echolocating for food and the like. Instead of silence, Delle was a one-dolphin band, producing a wide range of sounds. And it wasn't just feeding or navigating. He was "talking" to anything that would listen, even if it was just to himself.

Dolphins are incredibly smart and social mammals that typically live in a pod. Dolphin communication systems are regarded as being very complex and even share parallels with how humans communicate. "Signature whistles" are unique to each dolphin in a way that names are unique to a person (I wonder how many dolphins share the name "James?").

Dolphins will identify themselves with a signature whistle and even mimic another dolphin's signature whistle to interact with a specific member of the pod. "Hey James, it's James! Wanna party? I got some sardines!"

So what's he saying?

For starters, Delle has been vocalizing three unique signature whistles, which is weird. Researchers think that because Delle has been isolated without social interaction for so long, it's affecting his behavior. He might be doing it to amuse himself or calling out the "names" of dolphins he once used to hang out with. It could just be a coping mechanism to get him through the day. The reasons are all speculative as this type of solo-act-dolphin phenomenon isn't commonly observed. Maybe he has split personality disorder? Traditionally, dolphins are believed to have a one-whistle-per-dolphin system, but Delle threw that theory out the window with his triple-whistle repertoire.

Delle doesn't stop at just whistles. He throws in something called biphonic sounds – that's when you make two noises simultaneously. We're not sure why dolphins do this, but it might be to add more layers of complexity in their communication to one another. Some people can do it. We call it overtone or throat singing. It's rare for dolphins to do, but it has been observed before so it's not entirely unique.

Delle, on the other hand, is full of biphonic sounds, including combinations of whistles, low-frequency tonal calls, and burst-pulse sounds ... due to the lack of conspecifics anywhere nearby, Delle might just be stretching out his two sets of phonic lips (the dolphin version of vocal cords) and just experimenting his vocal range. Granted, bottlenose dolphins have been known to often communicate with others several miles away.

Among his most commonly made sounds were rhythmic low-frequency noises known as "gulps." Researchers have linked gulps to everything from feeding (no pun intended) to social excitability. Delle has been doing it for seemingly no other reason than to hear himself, very much like when you, Dear Reader, sing in the shower when no one is home.

Scientists have a few theories why Delle is talking up a storm:

Delle might just be sad and lonely and the sounds could be expressions of emotion either intentionally or unintentionally. Most animals vocalize basic emotions. For example, when your pet pooch cries in happiness when you get home or sadness when you leave.

Or Delle might be "singing the song of his people" in hopes the find his fellow dolphins. Though, having spent the last three years in the same spot with no other cetaceans in sight, you'd think he'd have realized he simply wasn't invited to the party.

Another assumption – as many of his sounds came in rhythmic bouts and often during his signature aerial flips – perhaps he was just in the mood for some wicked beats to get his dance on.

Delle's chatter raises as many questions as it answers. Is it a sign of emotional complexity? Is he practicing his sounds like a dolphin musician? Or is it simply a reflection of his natural urge for social interaction? In the end, maybe Delle (or bottlenose dolphins in general) isn't so different from us. We all have the desire to be heard, even if no one is listening.

At least Delle hasn't taken up wearing tuna fish hats like some other dolphins we know.

Source: Taylor and Francis