Kiss squeaks


Orangutans in Indonesia’s Borneo island have devised an ingenious technique to lower the frequency of their alarm calls called kiss squeaks.

The apes use leaves to alter the frequency of the kiss squeaks and make the calls sound deeper. As deeper calls are usually associated with larger animals, predators like leopards, snakes and tigers are fooled into thinking the ape is larger than it actually is and hesitate to attack it. According to Madeleine Hardus, a primatologist from the University of Utrecht, Netherlands, orangutans are the only non-human primates that have been found using tools to manipulate sound.