Bornean Orangutan Kiss Squeak for Hopeless Romantics (Sound of the Day) by Pro Sound Effects

This kiss-squeak sound is a defensive mechanism orangutans developed to trick intruders or predators into thinking the individual is bigger than he or she really is. Not to suggest the Bornean Orangutan is a pushover, exactly—their strength is approximately seven times greater than the average human's—but it is an endangered species.