"As far as we know this is the first time such contact calls have been described for river dolphins." These calls were emitted by calves as they reunited with their moms," Collado said. "One type of sound stood out from the others we called it the two-component call. Many of the sounds were short, two-part calls, which baby dolphins made when approaching their mothers. But even with nearly an entire day of material, the team speculated that the dolphins can produce more sounds than they recorded. Overall, they captured around 20 hours of recordings, identifying 237 different types of sounds. In addition, they took some DNA samples from the animals. Here, the team used underwater cameras and microphones to record the sounds and interactions between the dolphins at the market.
A traditional method to study cetaceans is by photographing the natural marks of their dorsal fins-or tails in the case of whales."įortunately, the research team was able to find a fish market in the town of Mocajuba where the dolphins often visit because people give them food. "In addition, their dorsal fin is very small which makes it very difficult to identify individuals using natural marks. "They are hard to study because they difficult to find in their natural environment they do not break the water surface as true dolphins do, making it hard to spot them in the field," Collado said. We know very little about their biology." "They also show low levels of genetic diversity, which makes them more vulnerable to human threats. "The Araguaian river dolphin is rare because their distribution is restricted and are presumed to have low population size," Collado said. They live only in the waters of the Araguaia and Tocantins rivers, and their numbers likely do not exceed more than one and a half thousand in total. Little is known about the Araguaian dolphins, also known as botos, as they are hard to find, as well as difficult to approach. Recent advances in acoustic technology are allowing us to study the extent of their acoustic repertoire and the context in which these sounds are produced." Our study shows that unlike other river dolphins, the Araguaian dolphin is quite chatty. "However, we now know that like other cetaceans, sound plays a key role in their daily life. "In the past, these animals were thought to be silent," Laura May Collado, a biologist at the University of Vermont, told Newsweek. Because of this assumption, it was believed that the animals would not be capable of complex communication, given that their social structure does not require it.īut now, scientists from the University of Vermont have discovered that the dolphins do interact with one another and can make hundreds of different sounds for the purposes of communication, according to a study published in the journal PeerJ. The rare Araguaian river dolphin is a mysterious creature, native to Brazil, that researchers have long thought to be solitary.
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