Ultrasonic communication in Tarsiers

In the New York Times yesterday, I found this article on a recently published piece in Biology Letters. A group of researchers in the Philippines captured several tarsiers and measured auditory sensitivity and also recorded vocalizations. Tarsiers best auditory sensitivity regions are 1.4 and 16 kHz and their audible range extends to 91 kHz (the ultrasonic range - inaudible to humans) - that's the highest recorded value for any primate and on par with only a few mammals such as bats and cetaceans. Additionally, they also recorded vocalizations that were pure ultrasound (approx. 70 kHz). In summary, tarsiers can receive ultrasonic signals (for instance, from the insects they eat) or send ultrasonic signals to conspecifics.