Male mice serenade potential mates with ultrasonic love songs, a study by US scientists has revealed.
The ultrasonic chirps emitted by mice resemble birdsong
The research adds mice to the exclusive club of mammals that can sing, which has until now comprised only human beings, bats and cetaceans.
A Washington University, St Louis, team studied ultrasonic squeaks emitted by mice when they smelt a female and found that they formed complex songs.
They have published details in the scientific journal PLoS Biology.
Scientists have known for some time that mice emit sounds at a frequency outside the range of human hearing, but it was always possible that these could have been random vocalisations.
Washington researchers Tim Holy and Zhongsheng Guo now demonstrate that this is not the case.
They discovered the songs by accident, while investigating how male mice responded to sex pheromones released in the urine of female mice.
When the males encountered cotton swabs dunked in female mouse urine, they broke into song.
Dr Holy and his team processed the sound recordings to make them audible to humans, lowering the pitch without interfering with the tempo.
Instead of making the ultrasonic chirps randomly, the mice used several different types of syllables arranged in regular, repeated time signatures resembling birdsong.
Their vocalisations meet the characteristics of song, Dr Holy and Dr Guo claim.
Singing plays a prominent role in the courtship rituals of amphibians, birds and insects; but it is known only in a handful of mammals, such as bats, humans, and cetaceans, which include whales and porpoises.