[LINK] "Underwater Victory Squeals Signal a Job Well Done"

[rfmcdonald]

Wired's Mary Bates notes new evidence for a high level of intelligence among cetaceans: they celebrate with speech acts.

Sam Ridgway first noticed the sounds he would come to call ‘victory squeals’ in 1963. When three new dolphins arrived at his research facility, an engineer placed underwater microphones in their pool. As the researchers tossed in mackerel for these animals who had not eaten in 36 hours, Ridgway noticed that each dolphin gave a squeal as it seized a fish.

In the over fifty years since that day, Ridgway has heard this sound thousands of times. In echolocation circles, the sound is known as a feeding buzz. Like bats, dolphins and some other cetaceans use echolocation to find their prey. As they close in on a food item, the animals emit more rapid pulses. After a cetacean catches a fish, the clicking becomes so fast that it sounds like a squeal to human ears.

Ridgway, however, thought this squeal indicated more than just the capture of a fish. Unlike bats, cetaceans continue the feeding buzz after they have captured their prey, suggesting the sound may also have emotional content.

“When we train dolphins and belugas, we reward them with fish for correct responses,” Ridgway says. The trainers whistle after the animal performs the correct response, a sound that indicates to the animal that it will get a fish reward. Ridgway and his colleagues were surprised to notice that dolphins and belugas gave the squeal not only after receiving their fish, but after the whistle, as well.

Ridgway started calling this sound a victory squeal after an experiment in the 1960s with a dolphin named Tuffy. To see how deep Tuffy could dive, Ridgway and his colleagues set up a task in which the dolphin had to dive to the bottom of the ocean to turn off a tone by flipping a switch. “Each time the sound went off, the animal would squeal,” Ridgway says. “When he accomplished the deep dive, it certainly seemed to us to be a victory.” On hearing the squeal, Ridgway’s wife Jeanette said it reminded her of a child’s squeal of delight; hence, the victory squeal.