Solitary Dolphin Communicates Uniquely in the Baltic Sea
Unusual vocalizations recorded from a lone bottlenose dolphin in Denmark
Researchers have discovered a solitary bottlenose dolphin in the Baltic Sea, named Delle, exhibiting unique vocal behaviors.
Found near the Svendborgsund channel, south of Funen Island in Denmark, Delle has been alone since September 2019, a region typically not inhabited by bottlenose dolphins.
Conducting a study over 69 days from December 8, 2022, to February 14, 2023, scientists recorded Delle producing 10,833 sounds, including whistles, burst pulses, low-frequency tonal, and percussive sounds.
Contrary to the usual singular signature whistle each dolphin possesses, Delle produced three different types of stereotyped whistles and biphonic sound categories.
Researchers, led by Olga Filatova and published in the journal Bioacoustics, propose two theories for these vocalizations: involuntary sounds similar to human laughter, or calls to attract nearby dolphins.