Featured in the May 2011 issue of Smithsonian magazine is an article about the vocalizations of different species of mice. Matina Kalcounis-Rueppell, biologist at the University of North Carolina, Greensboro, is a behavioral ecologist with expertise in how animals use sound. While working a California field site in 2004, she used an ultrasonic recorder ( analogous to Gordon's Bat Box ) to capture nighttime sounds, some of which she suspected to be those of mice she was studying.
Bringing the recordings into the computer, Matina's team noticed a fairly loud four-note song that turned out to be from a deer mouse. A slowed down recording of the mouse song sounds eerily akin to whale song. Have a listen.