Frank Sinatra had nothing on these guys:
...it now appears that male mice may serenade potential mates with melodies approaching the complexity of bird song.
Mouse songs are sung at ultrasonic frequencies, which is why no one has noticed their complexity before, nor indeed been moved to celebrate the tunes in romantic poetry.
....Tim Holy and Zhongsheng Guo, of Washington University School of Medicine in St Louis, Missouri, US, recorded the vocalisations made by male mice in the presence of female pheromones. They then digitally modified them to drop the pitch by several octaves into the range of human hearing.
....The function of the mouse song is not yet known, but given that the males are stimulated to sing when they smell female pheromones, it seems likely that singing attracts females.
If mice are singing to serenade females, the song should contain information about their “quality” as a potential mate, say the researchers, and they found some evidence to support this. ....there could be information about male quality in the song," with stronger males being able to sing better.