It has been discovered that male mice sing, almost certainly to serenade the laydee mice.
Some bats are known to sing in courtship, and whale song is well-documented, but singing is otherwise unknown in non-human mammals. That it has turned up in one of the most well-studied of animals – the lab mouse – is all the more surprising.
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.