It's true: Mice actually sing, especially when they're looking for a mate. That's not anything new. But unlike birdsong, mouse-song is much too high-pitched for humans to hear. So no, it's not exactly Cinderella-esque, as you can hear for yourself in the above video. But it is shockingly intricate.
In a new study published Wednesday in Frontiers of Behavioral Neuroscience, researchers at Duke University took a new approach to analyzing mouse songs: They analyzed them the way scientists analyze bird songs. They looked for changes in the way mice string together syllables, hoping to analyze whether they used and responded to different songs in different situations.
Sure enough, male mice on the lookout for an unseen female (an illusion the researchers created by exposing them to female urine) gave loud, complex song performances. But once they were in a female's presence, they simmered down. Females seemed to be more receptive to those first, more complex songs.
The study authors believe the male mice may be expending extra energy when a female isn't in sight, but doing the bare-minimum singing when she's nearby. That leaves the male mouse with extra energy to physically pursue her and attempt to mate. So he's basically wining and dining her when she's elusive, then turning his sights to sex once she's within reach.
In any case, the researchers believe they've shown that mouse song varies a surprising amount based on social context.
"Few people know that mice actually sing, even in the scientific community," study author Jonathan Chabout explained. "It's easy to study birdsong because you can actually hear them. Mice emit ultrasounds, out of human range." Plus, he said, birdsong makes more sense to study: Because birds can learn to sing new songs, they're the closest animal model we have for the process of a human learning to speak. Mouse songs are innate.
But even though they're not as human-like as bird songs, mouse sounds do depend on the occasion.
"The most surprising thing was that male mice were changing not only their singing repertoire, but also their syntax according to the context they were in," Chabout said. He and his colleagues can't be sure whether the mice were pulling from a variety of canned songs or creating them on the fly to suit the mood, but they hope to find out through further study.
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