You would think It will be easier to monitor Risso’s dolphins. This species appears on almost every coast in the world. Their protruding heads and striped gray-white patterns make them one of the most well-known creatures in the ocean. Like other cetaceans, they travel in groups and chat constantly: clicks, hums, and whistles help them understand their presence underwater. Their social world is a sound world.
“They are a very vocal species,” said Charlotte Curry, An expert in bioacoustics. “Sound is very important to them.”
Curé works at the French Joint Research Center for Environmental Acoustics, where she reveals how cetaceans use environmental sounds to make smart decisions.Dolphins are well known comminicate Directly with each other and echo locate their prey before attacking. But many years ago, she wondered if they could also receive information that was not suitable for them from other dolphins.
But the problem is that even though dolphins are talkative, Cure and Fleur Visser, Her collaborator and Risso’s behavioral expert, can speak this language.Therefore, instead of spying on what the dolphins seem to be saying, they focus on how they are moveIn their experiment, Cure’s team tested the reaction of dolphins when the researchers parked the boat overhead and played social noise recorded by other groups.
After four years of field research, Cure’s team reported their results: First evidence Cetaceans eavesdrop on each other and use this information to decide where to swim next. For example, it is well known that males harass females, cubs, and social records of males fighting against other males, driving away most dolphins.Their research was published last month Animal cognition.
According to Caroline Casey, a marine mammal acoustic communication expert at the University of California, Santa Cruz who was not involved in the study, this work is a masterpiece of animal espionage. “It’s just like humans,” she said of the eavesdropping behavior of dolphins. “And I like that experiments can show what seems obvious to us, but it hasn’t been proven in very elusive animals before.”
After all, although Risso’s dolphins are easy to spot, it is difficult to listen to their secrets. But because cetaceans are very intelligent and very dependent on language, studying their communication can help us understand the origin of our own language. More practically, knowing how to lure and repel these dolphins shows a new tool for protecting them.
Dolphins are not Only noisy, nosy animals. Scientists have proved that male red-winged blackbirds are in conflict on the territory, Eavesdrop on each other’s quarrels To measure the aggressiveness of potential opponents.The female great tit songbird participates in the male singing contest, and then deceive They partnered with the more dominant tweeter. birds with bat Eavesdropping when looking for a partner and food. In each case, the researchers suspected that the human voice would trigger some known behavior. Therefore, in order to test the animal’s response, the researchers played recordings of these sounds through speakers and observed what would happen.
But Kuray’s team is curious about the animal communication that occurs below sea level, and this is even more mysterious. Until about ten years ago, researchers did not have the right tools to prove that such a large marine mammal can hear and respond to chatter from a distance. “Now we have some tools,” Cure said.With a ship carrying Underwater speaker, The researchers used drones to track movement from overhead and tags (suction cup acoustic sensors) to mark their test subjects.
They tracked about 14 individual dolphins and groups of dolphins near the coast of Terceira Island in the Azores. Dolphins usually swim in a straight line. But Cure hypothesized that the voice reveals social information that might deviate them. Sitting on the “player”, she will prompt three sounds. One is the clicking and buzzing of dolphins as they forage for food-the “dinner bell” is considered an attractive signal that others will swim towards.Another recording with social whistle and “Burst” The male voice is considered a threat signal that will repel females and competitive males. They also play endless chatter from women and Mavericks, which are considered neutral.