London, April 2 (IANS): Male mice sing surprisingly complex songs to seduce females, similar to songbirds, according to a new study.

The researchers found that males sing more complex songs - and louder - when they smell a female's urine but don't see her.

By comparison, the songs are longer and simpler when the males sing directly to the female in her presence found the study published in the Frontiers of Behavioral Neuroscience.

"We think this has something to do with the complex song being like a calling song, and then when he sees the female, he switches to a simpler song in order to save energy to chase and try to court her at the same time," said co-corresponding author Erich Jarvis from Duke University.

"It was surprising to me how much change occurs to these songs in different social contexts, when the songs are thought to be innate," Jarvis added.

For more than 50 years, it has been known that mice sing. That is, they emit what's called 'ultrasonic vocalisations' or USVs, sounds so high-pitched that people can't hear them.

These vocalisations are known to occur in the wild when a mouse pup calls for its mother.

And USVs grow more complex as mice reach adulthood. But researchers are still trying to decode the songs and determine how they vary across different social situations.

"It is clear that the mouse's ability to vocalise is a lot more limited than a songbird's or human's, and yet it's remarkable that we can find these differences in song complexity," the researchers said.

Most female mice prefer spending time by speakers playing the complex tunes.

The fact that the females reacted differently to the different songs further strengthens the group's conclusion that these various calls carry meaning, researchers said.