Rats squeak with happiness when they are with another rat

Rats emit a high-pitched squeak when around another rat, seemingly just to express a positive emotion

By Christa Lesté-Lasserre

7 November 2023

Rats aren’t always communicating with each other when they squeak and squawk – sometimes they are just happy to be together

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Rats seem to emit ultrasonic squeaks of happiness just because they are in the company of another rat.

Using newly developed miniature microphones that were placed on rats’ noses, scientists have been able to determine which individual rat is making high-frequency sounds at any given moment. In an unexpected result, the recordings show that the rats weren’t squeaking as a way of communicating with each other or in response to anything their fellow rats did, but simply out of the joy of being together, says Shai Netser at the University of Haifa in Israel.

“We think that this isn’t a language, but actually another way to pronounce happiness in general,” he says.

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People can hear the “alarm” squeaks that rats sometimes make when they are distressed, but most rodents’ calls have frequencies well beyond the human hearing range, which in adults usually maxes out at around 17 kilohertz.

Scientists have previously discovered that rats make very high-pitched, choppy squeaks (at about 50 kHz) when they are happy and make lower-pitched, longer calls (at about 22 kHz) when they are discontented. This is somewhat akin to dogs barking with happy excitement or growling when they are angry, says Netser.