Covert Communications Channel in Tarsiers
Marissa A. Ramsier, Andrew J. Cunningham, Gillian L. Moritz, James J. Finneran, Cathy V. Williams, Perry S. Ong, Sharon L. Gursky-Doyen, and Nathaniel J. Dominy (2012), “Primate communication in the pure ultrasound,” Biology Letters.
Abstract: Few mammals — cetaceans, domestic cats and select bats and rodents — can send and receive vocal signals contained within the ultrasonic domain, or pure ultrasound (greater than 20 kHz). Here, we use the auditory brainstem response (ABR) method to demonstrate that a species of nocturnal primate, the Philippine tarsier (Tarsius syrichta), has a high-frequency limit of auditory sensitivity of ca 91 kHz. We also recorded a vocalization with a dominant frequency of 70 kHz. Such values are among the highest recorded for any terrestrial mammal, and a relatively extreme example of ultrasonic communication. For Philippine tarsiers, ultrasonic vocalizations might represent a private channel of communication that subverts detection by predators, prey and competitors, enhances energetic efficiency, or improves detection against low-frequency background noise.