Mice 'Sing' to Establish Territory [VIDEO]

New research on singing mice in Central American rainforests reveals that the rodents not only use their song to to attract mates and ward away foes, but to establish territory as well.

The research shows for the first time that male singing mice use their trills to create geographic boundaries between species.

Working deep in the mountain cloud forests of Costa Rica and Panama, the researchers studied the Alston's singing mouse (Scotinomys teguina) and the Chiriqui singing mouse (S. xerampelinus), finding that the songs cue the smaller Alton's mouse to steer away from its larger cousin.

"Most people are puzzled by the existence of singing mice, but in reality many rodents produce complex vocalizations, including mice, rats and even pet hamsters," said Bret Pasch, a postdoctoral fellow in the Department of Integrative Biology and lead author on the paper, which was published online in the journal The American Naturalist. "Often they're high-pitched and above the range of human hearing."

Though smaller and more submissive, the Alton's singing mouse produces a longer, higher-pitched call than its larger cousin the Chiriqui, but the songs of both mice are barely audible to humans.

Pasch said that the mice songs consist of rapidly repeated notes called trills, which are produces each time the mouse opens and closes its mouth, roughly 15 times each second.

Because the two mice share a similar diet and habitat, their lives often tend to overlap.

"A long-standing question in biology is why some animals are found in particular places and not others. What factors govern the distribution of species across space?" said Pasch.

Pasch and his colleagues observed that the larger Chiriqui mice prefer the cooler temperatures of higher altitudes. The smaller Alton's mice are more temperature tolerant, but in the absence of dominant Chiriqui mice, the Alton's mice will spread into the territory. But as soon as the Alton's mouse hears the song of the Chiriqui, it will retreat without even putting up a fight.

"The use of communication in mediating species limits is the major finding of our study and provides insight into how large-scale patterns are generated by individual interactions," said Pasch.

Alston's singing mouse (Scotinomys teguina) calling in the clouds from bpasch on Vimeo.