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Whales and Dolphins Squeal With Delight, Study Finds

A photo of a bottlenosed dolphin
A bottlenose dolphin calls. Photograph by Frans Lanting, National Geographic Creative

Beluga whales and bottlenose dolphins express their pleasure by squealing like children, a new study suggests for the first time. 

The squeaky sounds, which are different from the echolocation buzzes some whales and dolphins use to home in on prey, suggest there’s yet another aspect of behavior that people share with marine mammals, among the smartest groups of the animal kingdom.

For decades, scientists and marine mammal trainers have noticed these “extra” vocalizations when they rewarded captive animals with food. They have also observed it in wild animals.

Some have brushed it off as an inadvertent artifact of the training process, or figured it was a part of the food calls some whales and dolphins make. (See “Dolphins Have ‘Names,’ Respond When Called.”)

This new work, published August 13 in the Journal of Experimental Biology, suggests that belugas and bottlenose dolphins make the noises to express their delight.

It’s a fun and creative study, Paul Nachtigall, director of the marine mammal program at the University of Hawaii in Kane’ohe Bay, said in an email.

Nachtigall, who was not involved in the study, has also noticed the sounds in some of the trained dolphins he’s worked with.

“I had one of my dolphins during my dissertation emit a little squeak each time he pressed a paddle, even though he only received food on the average of once per minute,” he said.

“I always thought it was inadvertently trained,” Nachtigall recalled. “This [new study] could be an alternative explanation.”

“Victory Squeal”

The study authors, led by Sam Ridgway of the National Marine Mammal Foundation in San Diego, California, trained captive bottlenose dolphins and beluga whales to perform various tasks in return for a fish reward. They found that the buzzes the animals emitted while approaching the fish continued after they had grabbed their reward.

Ridgway and colleagues called the pulsed buzzes after the animal captured the fish the “victory squeal.” They also surmised that the animals weren’t using the sounds to locate the fish. (Learn about the sensory capabilities of bottlenose dolphins.)

“Why continue to make buzzes [to locate the reward] when the fish is in your mouth?” noted the University of Hawaii’s Nachtigall.

Trainers then associated a secondary signal—usually a whistle—with the fish. Over time, trainers started giving the secondary signal before the reward. Ridgway and colleagues found that their belugas and bottlenose dolphins would emit their squeal after the whistle but before they grabbed their fish—strongly suggesting that the animals expected a reward, the study authors wrote. (See “Dolphins Have Longest Memories in Animal Kingdom.”)

The researchers then compared the time it took the belugas and dolphins to emit their victory squeal in response to the secondary signal versus a general vocalization in response to a different sound. They found a longer delay between the victory squeal and whistle than for the vocal response and sound.

That delay—151 milliseconds on average—is in the range of release times for a brain chemical called dopamine, which is also observed in land mammals (including us) that have been trained to expect a reward, the study authors wrote. (See “‘Talking’ Whale Could Imitate Human Voice.”)

Dopamine, which acts as a kind of messenger between nerve cells in the brain, plays a big role in how humans register pleasure or happiness.

So it’s likely that victory squeals in belugas and dolphins occur when their brains have released dopamine, according to the study.

A Note of Caution

Maddalena Bearzi, a marine mammal biologist and president of the Ocean Conservation Society in Marina del Rey, California, urges caution in taking the results of this study too far.

“It’s a bit of a stretch to say [the squeal] is emotional,” said Bearzi, who was not involved in the research.

“Based on 25 years in the field, I do believe these animals are emotional creatures,” she said.

It’s certainly possible that these squeals represent pleasure in bottlenose dolphins and belugas, Bearzi said, but there aren’t enough data to rule out other possible explanations.

She would like to see further studies delving deeper into this question. “Emotion is so hard to define in us, let alone in a dolphin.”

Follow Jane J. Lee on Twitter.

Comments

  1. Boris Blagojevic
    Topola Serbia
    August 19, 10:21 am

    What is that redone on the bottom side of dolphin’s mouth it’s look like an wound.Is this dolphin injured,hurted?Please just pay attention of that little red what is look like a living wound an injury.Very Seriousely.

  2. Jeanne
    United States
    August 18, 10:58 pm

    They are stretching their conclusions to assume this is a squeal of delight. It could also be a squeal of frustration for being in captivity and teased with food. Research done on captive cetaceans can rarely mimic their true behavior in the wild. Please….

  3. Emil Petruncio
    Arnold, MD
    August 17, 11:04 pm

    While standing watch as Officer of the Deck on a U.S. Navy frigate back in the late 80s, I sometimes switched on our underwater telephone (AN/WQC-2) to briefly listen to the vocalizations of dolphins swimming in our bow waves. Their squeals reminded me of kids on the playground – they seemed to be taking delight in the open ocean surfing.

  4. Russ Chiodo
    Destin, FL
    August 15, 10:00 am

    You only have to go to Dolphin Research Center in the Florida Keys to witness this! The dolphins there squeal in celebration of each correct behavior.

  5. Linda Erb
    Florida Keys
    August 14, 11:13 pm

    Way to go Dr. Sam Ridgway!! We have always seen/heard this at Dolphin Research Center, and not just associated with fish. The dolphins squeal regularly when simply playing with their trainer friends! Nice to have science back up the think we’ve long believed, that they are enjoying our company as much as we are enjoying theirs!

  6. jay taltos
    liverpool uk.
    August 14, 12:01 pm

    very intelligent ? me thinks. ‘ thanks for the fish ‘ ! ( only joking ). smiles.