The Philippine tarsier is one of the world’s smallest primates, now discovered to be able to communicate in ultrasound frequencies, according to a study.
Only a handful of mammals are known to be able to send and receive vocal signals in the ultrasound range, above 20 kilohertz (kHz), including some whales, domestic cats and a few of the many species of bats.
And few of these can squeal, screech or squawk at the same sonic altitudes as the saucer-eyed tarsier, which up to now had been mistakenly described as being ‘ordinarily silent,’ researchers found.
No bigger than a man’s hand, Tarsius syrichta can hear and emit sounds at a frequency that effectively gives it a private channel for issuing warnings or ferreting out crickets for a nighttime snack, the study found.
Lacking the typical ‘night vision’ of other nocturnal creatures, they also have, in relation to their body size, the largest eyes of any primate on Earth.
Its finely-tuned ears are capable of picking up frequencies above 90 kHz, and it can vocalize in a range around 70 kHz.
By comparison, humans generally can’t hear anything above 20 kHz, and a dog whistle is pitched to between 22 and 23 kHz.
The tarsier’s exceptional hearing may also facilitate acoustic eavesdropping on noises emitted by prey, which range from crickets and cockroaches, their staple diet, to the occasional moth, katydid or hatchling bird.
“Ultrasonic calls can be advantageous to both the signaler and receiver as they are potentially difficult for predators to detect and localize,” the researchers explain.
A team of scientists from the United States and the Philippines led by Marissa Ramsier of Humboldt State University in California conducted the tarsier experiment.