"Mice are better than birds to study because they are mammals and much closer to humans in their brain structures and other biological aspects," Uchimura said.

However, such is Uchimura' agreed to waive the bulk of the cost after he explained his mistake — and instead implemented a flat-rate roaming charge of about $30 a day.

"Studying the effects of the chirping sound on other mice could promote research into the evolution of mammalian verbal communications," said Arikuni Uchimura, the researcher from Osaka University.