Male house mice produce melodious songs to attract mates, but being in the ultra-sonic range our ears cannot detect them.

Through analyses of the vocalizations of wild house mice, researchers at the University of Veterinary Medicine, Vienna, have found that the songs of male mice contain signals of individuality and kinship. It has been known for some time that house mice produce ultrasonic vocalizations (USVs) during courtship but it has generally been assumed that these are no more than squeaks, the journal Physiology & Behaviour and the Journal of Ethology report. 

However, analyses have revealed that USVs are complex and show features of song. Although the vocalizations are inaudible to human ears, when playbacks of recorded songs are slowed down their similarity to bird song becomes striking, according to a Konrad Lorenz statement. 

Frauke Hoffmann, Kerstin Musolf and Dustin Penn of the University of Veterinary Medicine Konrad Lorenz Institute of Ethology aimed to learn what type of information is contained in males' songs for the discerning ear of the female mouse to detect. 

Their initial studies, the first to study song in wild mice, confirmed that males emit songs when they encounter a females' scent and that females are attracted to males' songs. Additionally, the scientists discovered that females are able to distinguish siblings from unrelated males by their songs - even though they had previously never heard their brothers sing.

They found that males' songs contain "signatures" or "fingerprints" that differ from one individual to another. Moreover, they confirmed that the songs of siblings are very similar to one another compared to the songs of unrelated males, which helps explains how females can distinguish unrelated males.