Mysterious river dolphin helps crack the code of marine mammal communication

[Judi Lynn]

19-APR-2019

UNIVERSITY OF VERMONT

The Araguaian river dolphin of Brazil is something of a mystery. It was thought to be quite solitary, with little social structure that would require communication. But Laura May Collado, a biologist at the University of Vermont, and her colleagues have discovered that the dolphins can actually make hundreds of different sounds to communicate, a finding that could help uncover how communication evolved in marine mammals.

"We found that they do interact socially and are making more sounds than previously thought," she says. "Their vocal repertoire is very diverse."

. . .

The Araguaian dolphins, also called botos, are a difficult animal to study. They are hard to find in the first place, and while the waters of the Araguaia and Tocatins rivers are clear, it is challenging to identify individuals because the dolphins are skittish and hard to approach.

Luckily, Gabriel Melo-Santos, a biologist from the University of St Andrews in Scotland and leader of the project, found a fish market in the Brazilian town of Mocajuba where the botos regularly visit to be fed by people shopping there. The clear water and regular dolphin visits provided a unique opportunity to get a close look at how the animals behave and interact, and to identify and keep track of various individuals.

More:
https://www.eurekalert.org/pub_releases/2019-04/uov-mrd041619.php

[Judi Lynn]

1. Rare Recordings of Elusive River Dolphins Show They Are Surprisingly Chatty

By George Dvorsky on 19 Apr 2019 at 12:00PM

Discovered to be a unique species just five years ago, the Araguaian river dolphin of Brazil is a fascinating, yet poorly understood, aquatic creature. As new research shows, these dolphins produce a surprising array of sounds—an important clue in our understanding of how and why dolphins evolved the capacity for communication.

The Araguaian river dolphins, also known as botos, were first identified in 2014. Botos live exclusively in the Amazon, Orinoco, and Tocantins River Basins of South America, where they use their long beaks to hunt for fish.

These dolphins are considered evolutionary relics, having diverged from other cetaceans (a family that includes dolphins and whales) earlier than other dolphins. Because of their unique position within the cetacean family tree, scientists can study these creatures to better understand the ancestors of marine dolphins, such as the bottlenose dolphin. What’s more, by studying botos in the wild, scientists can acquire new insights into the origin of certain dolphin behaviours, such as their communication skills. Biologists would like to know, for example, if those iconic clicks and whistles emerged as a consequence of river life or ocean life.

Botos are notoriously elusive. Unlike marine dolphins and their dramatic breaching displays, botos don’t make a fuss when they come up for air. They tend to be solitary and shy, living in small social groups. These dolphins are critically endangered, and there may be only 1,000 of them left. Not much is known about their ability to make sounds or communicate with one another, but research done a few years ago suggested they’re able to make noises like clicks, whistles, jaw-snaps, and other sounds. Beyond this, not much was known.

More:
https://www.gizmodo.co.uk/2019/04/rare-recordings-of-elusive-river-dolphins-show-they-are-surprisingly-chatty/

[MineralMan]

2. What's interesting to me is that these shy creatures

are not so shy about showing up for food at a town where they are fed by people. Once the scientists discovered that, they began to learn more about their vocalizations. There's a lesson there, I think.

It reminds me of a herd of deer in Yosemite National Park, near the south entrance of the park. There's a meadow there and a parking lot for something near that meadow. Despite the signs telling people not to feed the deer, dozens of deer are there almost anytime you stop. As many wild animals do, they have lost all fear of humans and immediately approach you if you get out of your car. Why? Because people feed them. Those deer are picky eaters, and have trained humans to bring them food they prefer, like apples.

So, the parking lot is full of cars, the meadow is full of deer and the people have bags of apples. There is close interaction between the deer and the humans, with no harm coming to either. I've never seen a park ranger there, telling people to go away and stop feeding the deer. This has been going on for years and years.

It's an interesting phenomenon. Of course, everywhere in Yosemite, small animals and birds have taught humans what they like to eat, as well. I was about 8 years old the first time I went to Yosemite with my family. We went to a naturalist talk, where the park naturalist called birds down to perch on his hands. I was amazed, until I noticed that he had seeds in the palm of his hands when he did that. So, I bought some seeds, and soon had birds flying down to my hands, as well. My parents were amazed, but I knew that the birds had taught the humans how to attract them. I just paid attention.

[Judi Lynn]

3. Enjoyed your post enormously. Seeing these beings at close range would be fascinating.Thank you. n/t

[MineralMan]

4. Thanks. My wife calls me the "critter whisperer."

The first time she came to my house in California, I walked her out into the front yard, put a peanut in the shell in her hand and said, "Here, hold your hand out, palm up." About 10 seconds later a jay landed on her hand, looked at her, picked up the peanut, and flew off. Now, 28 years later, she is an avid animal lover, and an active participant in our feeding station activities in front of our house.

We've lived here for 15 years now, and the same mated pair of mallard ducks shows up every spring to feed under our main bird feeder. We know it's the same pair, because the female has an oddly-colored feather or two on her tail. In years when they breed successfully, they bring their brood to our yard once they're fledged. The just returned the other day for another breeding season.