Bottlenose dolphin mother adopts melon-headed whale calf


This 5 August 2019 video says about itself:

Dolphin Mom Adopts a Calf From a Different Species | Nat Geo Wild

A bottlenose dolphin mother off the coast of French Polynesia was spotted caring for a melon-headed whale.

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How dolphins form friendships, new research


This March 2019 video is called How to Identify Indo-Pacific Bottlenose Dolphins.

From the University of Bristol in England:

Dolphins form friendships through shared interests just like us, study finds

June 12, 2019

When it comes to making friends, it appears dolphins are just like us and form close friendships with other dolphins that have a common interest. The findings, published in the Proceedings of the Royal Society B by an international team of researchers from the Universities of Bristol, Zurich and Western Australia, provide further insight into the social habits of these remarkable animals.

Shark Bay, a World Heritage area in Western Australia, is home to an iconic population of Indo-Pacific bottlenose dolphins, and the only place where dolphins have been observed using marine sponges as foraging tools. This learnt technique, passed down from generation to generation, helps certain dolphins, “spongers”, find food in deeper water channels. While the tool-using technique is well-studied in female dolphins, this study looked specifically at male dolphins.

Using behavioural, genetic and photographic data collected from 124 male dolphins during the winter months in Shark Bay over nine years [2007 to 2015], the team analysed a subset of 37 male dolphins, comprising 13 spongers and 24 non-spongers.

Male spongers spend more time associating with other male spongers than they do [with] non-spongers, these bonds being based on similar foraging techniques and not relatedness or other factors.

Dr Simon Allen, a co-author of the study and senior research associate at Bristol’s School of Biological Sciences, explains: “Foraging with a sponge is a time-consuming and largely solitary activity so it was long thought incompatible with the needs of male dolphins in Shark Bay — to invest time in forming close alliances with other males. This study suggests that, like their female counterparts and indeed like humans, male dolphins form social bonds based on shared interests.”

The study provides new insight into homophilous behaviour in the social network of tool-using dolphins.

Manuela Bizzozzero, lead author of the study at the University of Zurich, added: “Male dolphins in Shark Bay exhibit a fascinating social system of nested alliance formation. These strong bonds between males can last for decades and are critical to each male’s mating success. We were very excited to discover alliances of spongers, dolphins forming close friendships with others with similar traits.”

The study was funded by grants from the Swiss National Science Foundation, National Geographic Society, Australia’s Sea World Research and Rescue Foundation Inc (SWRRFI), W.V. Scott Foundation and the A.H. Schultz Stiftung.

Brazilian river dolphins communication, new study


This 2014 video says about itself:

A new species of river dolphin has been discovered by scientists working in Brazil. This is the fifth known species of its kind, and there are an estimated one thousand of the dolphins living in the Araguaia river basin.

Researchers from the Federal University of Amazonas ran genetic testing on some of the dolphins to be certain that a new species had been found. The last time a new species of river dolphin was discovered was back in 1918.

Doctor Tomas Hrbek, lead author of the study, is quoted as saying: “It is very similar to the other ones. It was something that was very unexpected, it is an area where people see them all the time, they are a large mammal, the thing is nobody really looked.” The Araguaia dolphins are smaller and reportedly have fewer teeth than the Amazon river dolphins, also called boto or pink dolphins, which are believed to be the most intelligent of the river dolphins.

From the University of Vermont in the USA:

Mysterious river dolphin helps crack the code of marine mammal communication

April 19, 2019

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 findings of May Collado are her colleagues were published in the journal PeerJ on April 18.

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.

The team used underwater cameras and microphones to record sounds and interactions between the dolphins at the market, and took some genetic samples. They identified 237 different types of sounds the dolphins make, but even with 20 hours of recordings the researchers don’t believe they captured the animals’ entire acoustic repertoire. The most common sounds were short, two-part calls that baby dolphins made when they were approaching their mothers.

“It’s exciting; marine dolphins like the bottlenose use signature whistles for contact, and here we have a different sound used by river dolphins for the same purpose,” says May Collado. The river dolphins also made longer calls and whistles, but these were much rarer, and the reasons for them are not yet clear. But there is some indication that whistles serve the opposite purpose than in bottlenose dolphins, with the botos using them to maintain distance rather than for group cohesion.

The acoustic characteristics of the calls are also interesting; they fall somewhere between the low-frequency calls used by baleen whales to communicate over long distances, and the high-frequency ones used by marine dolphins for short distances. May Collado speculates that the river environment may have shaped those characteristics.

“There are a lot of obstacles like flooded forests and vegetation in their habitat, so this signal could have evolved to avoid echoes from vegetation and improve the communication range of mothers and their calves,” she says.

May Collado and her colleagues next want to study whether the same diversity of communication is seen in other populations of Araguaian river dolphins that are less accustomed to humans, and compare them to their relatives elsewhere in South America. The Araguaian dolphins are closely related to two other species, the Bolivian river dolphin and Amazon river dolphin; the Araguaian dolphins were only described as a separate species in 2014, and that classification is still under debate. But there seems to be a large amount of variation in the repertoire of sounds each species makes.

The Amazon dolphins in Ecuador, studied by May Collado in 2005, are generally very quiet. “We need more information on these other species and more populations,” she says. “Why is one population chattier than others and how do these differences shape their social structure?”

May Collado says the work could help researchers gain clearer understanding of how communication evolved in marine mammals. Similar calls have been reported in pilot whales and killer whales, for example, and the similarities and differences between different species could help tease out which signals evolved first, and why.

The river dolphins are evolutionary relics, represented by just a few species around the world, and they diverged from other cetaceans much earlier than other dolphins. So these calls may have arisen first in river dolphins, then later evolved in marine dolphins into whistles and calls but in a different social context. Or was there a change in the function of the calls, with this kind of sound being used for group identity in killer whales, and individual identity in river dolphins? The calls may also have other functions in addition to identity, perhaps indicating group identity, or providing information on emotional state.

“We can’t say what the evolutionary story is yet until we get to know what sounds are produced by other river dolphins in the Amazon area, and how that relates to what we found,” she says. “We now have all these new questions to explore.”

Dolphins greet new born baby


This 28 July 2018 BBC video says about itself:

When a new baby dolphin is born, his family reunites around him to welcome him as one of them.

In a stunning new insight into the lives of wild dolphins, this film follows six remarkable months in the life of the ‘Beachies’: a family of six dolphins led by mother-to-be Puck, who live in the shark-infested waters of Western Australia‘s Shark Bay. Using the latest miniature cameras to eavesdrop on the Beachies’ underwater lives, this moving story follows Puck and the challenges she faces bringing up her newborn calf Samu. From learning to fish, to the ever-present threat of a shark attack, no day is ever the same. Including rarely seen footage of young dolphins and revelatory new behaviour, this is a heart-warming and emotional portrayal of one of the ocean’s most revered creatures.

Dolphin liberation in Korea


This video says about itself:

22 June 2015

I found dolphins at Jeju island in KOREA.

From the Ulsan National Institute of Science and Technology (UNIST) in South Korea:

Dolphin liberation in Korea

May 27, 2018

Summary: Biologists have carried out a scientific investigation on dolphin liberation in South Korea.

“Dolphin liberation in South Korea has raised awareness towards the welfare of marine animals and has resulted in the strengthening of animal protection policies and the level of welfare.”

An engineering student, affiliated with UNIST has recently carried out a scientific investigation on dolphin liberation in South Korea. The paper presents the overall analysis of the social impact of the first case of dolphin rehabilitation in Asia, which occurred in 2013.

This study has been carried out by Sejoon Kim in the School of Energy and Chemical Engineering in collaboration wit Professor Bradley Tatar in the Division of General Studies at UNIST. Their findings have been published in the April issue of the journal Coastal Management and will be published online, this month.

“After the release of captive dolphins from South Korean marine parks, there has been a growing environmental movement towards the conservation and management of marine and coastal ecosystems“, says Sejoon. “Although such movement relies on a single-species conservation focus and does not encompass an entire ecosystem, it has enormous symbolic significance for the welfare of marine animals.”

The research team hopes to expand their research to areas beyond the study of dolphin liberation and carry out in-depth case studies on various topics, including the whale-eating culture in Ulsan, the public perspective of dolphin shows, as well as the establishment of new types of dolphin life experience facilities.