Sperm whales change ‘vowel’ sounds when boats are nearby, scientists discover | Cetaceans
Researchers found that sperm whales make a specific clicking sound pattern when they hear the sound of boats. This pattern is so distinctive that the scientists who detected it said they can now use it to predict whether ships are nearby.
researchers Ceti Project (The Cetacean Translation Initiative), a nonprofit research organization trying to decipher sperm whale communication, spent four years listening to the calls of 15 sperm whales off the coast of Dominica.
They discovered specific differences in sperm whale “codas,” the distinct and distinctive clicking patterns this species makes to communicate when whales encounter ships. Individual click sequences became shorter and one type became more distinct than the other. Their findings: It was published In the journal Ecological Informatics.
“This research raises the question: Do whales talk about ships, or is it because ships are around that it affects their vocalizations,” said David Gruber, founder and CEO of Project Ceti. he said. “So if we can understand what they say about ships, how might that impact policy and law?”
Under normal conditions, recordings from one of the whales named “Atwood” detected a type of coda consisting of five clicks (two clicks before the faster three clicks) in a 1-1-3 pattern; Gruber explained that this is unique to this particular sperm whale clan off the Caribbean coast of Dominica. Atwood broadcast the same 1-1-3 click rhythm with the background hum of a ship, but noticeably faster, with the whale shortening the intervals between each click.
The connection was so strong that Gašper Beguš, linguistics leader of the Ceti Project, said, “In general, we can guess whether ships are around or not just from their vocalizations.”
For the research, Beguš and his colleagues recorded more than 1,000 codas from a 15-strong pod of sperm whales using audio tags attached to whales by drones with minimal intervention. Where background ship noise was detected, it was confirmed using digital geolocation data that ships were near the whale at the time the recording was made.
Various studies showed that there are sea animals increase volume But the researchers were surprised not to see this trend in sperm whales, finding that the creatures prioritize changing not only the speed but also the types of codas they produce.
This was related to previous studies in which Ceti Project researchers described the “use of vowels” in sperm whales. Communication between sperm whales has long been viewed as a series of clicks resembling Morse code; but in this study, the team found that if the spaces between individual clicks in a coda sequence were compressed to speed up recording, they formed a continuous phoneme resembling two human vowels; “aaaa” and “iiii” sounds.
In the latest study, in addition to varying coda tempo, the team also detected differences in the prevalence of these two vowel-like sounds in noisy conditions; Sperm whales use the “aaaa” coda more frequently.
“This study is actually one of the first signs that the vowels we discovered may actually carry meaningful information. Because in the presence of transport noise, they change the way they use these vowels,” Beguš said.
Some researchers criticized Ceti’s previous works, find fault to say that describing whale communication with terms such as “vowels” and “language” broadens the relationships between whale and human communication too much. Gruber says they try to address this concern by using terms like “vowel-like” or “language-like.”
Nathan Merchant, UK government underwater noise expert marine research agency CefasHe said there may be other unknown factors other than ship noise causing the change in whale calls, who were not involved in the study. But he said his “hunch” was that the relationship was causal.
Merchant noted that a majority of studies show changes in the behavior and call volume of marine animals when encountering shipping noise. “What makes this study stand out is that it shows changes in the fine-scale content of these calls,” he said. “This really adds another dimension of nuance to the story of how underwater noise can impact marine mammals.”
He added that more research is needed to determine what these audible changes mean.
“Are they [the whales] “Are they trying to say the same thing, or are they saying something different in the face of this noise?” he said. “That’s a really interesting question.”
