They also used a microphone and recording unit capable of registering sounds up 96 kHz. The upper limit of human hearing is generally set at 20 kHz, and frequencies above this limit are classified as ultrasound. In the field, the team recorded the sounds of 35 wild tarsiers from the islands of Bohol and Leyte with this equipment, documenting eight individuals giving out a purely ultrasonic call at approximately 70 kHz. The tone-like structure of the call resembles those of other tarsier species, but none were purely ultrasonic.
The researchers observed that tarsiers emitted their ultrasonic call when humans were near, suggesting they were voicing alarm. “Ultrasonic alarm calls can be advantageous to both the signaler and receiver as they are potentially difficult for predators to detect and localize,†they write.
Dominy and his group conclude that there may be selective advantages to vocalizations in the pure ultrasound. They call them “private channels of communication with the potential to subvert detection by predators, prey, and competitors.â€
“Our findings not only verify that tarsiers are sensitive to the ultrasound, but also that Tarsius syrichta can send and receive vocal signals in the pure ultrasound,†Dominy says.
Linkback:
https://tubagbohol.mikeligalig.com/index.php?topic=82015.0