"Vocal repertoire of captive northern and southern flying squirrels (Glaucomys sabrinus and G. Volans)."
Article in Journal of Mammalogy, Apr. 2019.
Dr. Gilley & Dr. Pearson say: Flying squirrels emit high-frequency calls barely audible or inaudible to human ears. They most likely communicate at higher frequencies to avoid being detected by predators. In this study, we described the vocal repertoire of high-frequency calls in two species of North American flying squirrels (northern and southern flying squirrels). We collected recordings from captive colonies of each species to generate a call library. Using visual and auditory assessments, as well as quantitative measurements, we identified and described 10 specific call-types for northern flying squirrels and 27 specific call-types for southern flying squirrels. Many of the calls have song-like properties, much like birds singing, only at much higher frequencies. In a “nutshell” flying squirrels use a host of syllables and phrases to communicate and “sing” at high frequencies.