Even mice sing.
We have known that for 50 years, but we are only recently beginning to understand the complexity of their songs. Part of the difficulty of studying mice songs lies in their ultrasonic vocalizations, frequencies the human ear cannot perceive: in the wild, this kind of calls happen for example when a mouse pup calls for his mother.

In April, in Frontiers of Behavioral Neuroscience, a new Duke University research appeared, showing how mice songs are really much more intricate than expected.
Researchers Jonathan Chabout, Abhra Sarkar, David B. Dunson and Erich D. Jarvis have exposed the mice to different social contexts and, using new specifically elaborated software, they have analysed the frequency modulation and duration of these ultrasonic calls. Researchers have been able to break down the songs into “syllables” and clusters of sound repeated to a certain rythm, and to discover how they vary according to the situation.

If a male mouse is exposed to female urine, and therefore gets convinced that she is somewhere nearby, his singing becomes louder and more powerful, if somewhat less accurate; to awake a sleeping female, he utilizes the same song, but the “syllables” are now pronounced much more clearly.
Female mice seem to prefer songs that are complex and rich in variations; even so, when a male finds himself near an available female, his elaborate courting song switches to a simpler tune. Once the potential mate has been attracted, in fact, our little mouse needs to save energy to chase her around and try to mate.

The mouse’s ability to sing is not as articulate as in songbirds; and yet, changes in the syntax according to social context prove that the songs convey some meaning and serve a precise purpose. Researchers are not sure how much mice are able to learn to modify their vocalizations (as birds do) or how much they just choose from fixed patterns. Forthcoming studies will try to answer this question.

It is nice to better understand the world of rodents, but why is it so important?
The goal of these studies is actually also relevant to humans. In the last decade, we understood how mice are extremely similar to us on a genetic level; discovering how and to what extent they are able to learn new “syllables” could play a fundamental part in the study of  autism spectrum disorders, particularly in regard to communication deficits and neural circuits controlling vocal learning.

Male mice song syntax depends on social contexts and influences female preferences, Jonathan Chabout, Abhra Sarkar, David B. Dunson, Erich D. Jarvis. Frontiers in Behavioral Neuroscience, April 1, 2015.