Abstract
Anecdotal reports of ultrasound use by flying squirrels have existed for decades, yet there has been little detailed analysis of their vocalizations. Here we demonstrate that two species of flying squirrel emit ultrasonic vocalizations. We recorded vocalizations from northern (Glaucomys sabrinus) and southern (G. volans) flying squirrels calling in both the laboratory and at a field site in central Ontario, Canada. We demonstrate that flying squirrels produce ultrasonic emissions through recorded bursts of broadband noise and time-frequency structured frequency modulated (FM) vocalizations, some of which were purely ultrasonic. Squirrels emitted three types of ultrasonic calls in laboratory recordings and one type in the field. The variety of signals that were recorded suggest that flying squirrels may use ultrasonic vocalizations to transfer information. Thus, vocalizations may be an important, although still poorly understood, aspect of flying squirrel social biology.
Highlights
Exploration of the use of ultrasonic vocalizations by animals began in the 1930s when it was discovered that katydids emitted high frequency sounds above the range of human hearing [1]
Broadband noise bursts were recorded both from isolated individuals and in the presence of conspecifics, and were produced by both male and female G. volans and a female G. sabrinus
Type 2 vocalizations consisted of a long duration signal with large amplitude modulation (AM) at the beginning of the call and a sinusoidal frequency modulation (SFM) structure
Summary
Exploration of the use of ultrasonic vocalizations by animals began in the 1930s when it was discovered that katydids emitted high frequency sounds above the range of human hearing [1]. The functions of ultrasonic vocalizations are well known for some animals, the use of ultrasound for signalling and communication is still unclear in many species. The purpose of our study was to document the use of ultrasonic vocalizations by two species of flying squirrel and describe the signals and the context in which they were recorded. Animals that emit higher frequencies for the purpose of communication must either invest more energy into the vocalization, giving it relatively more power and allowing it to propagate farther in the air and be more readily detected by both intended and unintended recipients, or senders must remain closer to receivers [4]
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