Orangutans manipulate their voices to scare predators

Chuck Bednar for redOrbit.com – @BednarChuck

In research that provides further evidence that some animals can learn how to modify sound, a team of experts from Belgium, The Netherlands, and the UK have captured footage showing how orangutans use their hands to alter their voices and make themselves sound more imposing.

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According to BBC News, the scientists found that the animals sometimes cup their mouths when producing an alarm call known as a “kiss squeak,” which typically signifies the presence of a predator in the area. By studying what the calls sound like both when the orangutans did and did not use their hands, they found that the calls sound “more impressive” when hands are used.

In a study published in this month’s edition of the Journal of Experimental Biology, the authors report that the voice-manipulation technique is used to try and scare off potential threats. If it can be proved that the orangutans are intentionally performing the enhanced “kiss squeak” knowing that it exaggerates their size, it may be indicative of an early precursor of language, showing that the animal is purposefully altering a call’s meaning.

Alarm calls that sound like kisses

“Orangutans may be aware that they can influence their call and it changes the reaction of the predator, and this is a simple form of learning, which is a very important first step in language,” study co-author Bart de Boers of the Vrije Universiteit Brussel in Belgium explained, according to Discovery News. The calls sound like kisses, he added, but they are actually alarm calls made when the creatures detect the presence of humans or dangerous animals.

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In the following video, approximately 20 seconds in, the mother orangutan notices the potential threat and responds accordingly, covering her mouth with her hand. The noise produced might sound like the creature is blowing a kiss, but that couldn’t be further from the truth – it was using its hand to lower the pitch of the sound to make it deeper, a rare feat for a wild primate.

“The problem is that the orangutan is not sitting still on a branch making its noises. There are cicadas singing in the background, rustling leaves – all kinds of horrible stuff going on,” de Boer said. Yet even with all of those other sounds and potential distractions, the altered call seems to match those made by bigger, more formidable primates and were even amplified thanks to the hand manipulation technique, he and his fellow researchers noted.

Musical monkey mouth

The creatures are using their hands to create “a cylindrical extension of the lips,” de Boer told BBC News. “This has the same effect as lengthening the sound box of a musical instrument, so you get resonance of the lower pitches” and makes them sound “more impressive.” However, he cautioned that while it is “unlikely” that it is being done by accident, “it’s still possible.”

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Determining intent will require several more hours of watching and recording the orangutans and analyzing the results, de Boer said. However, even the suggestion that they might be purposefully using their hands to scare off predators is an exciting development, he told the British media outlet.

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Source: http://www.redorbit.com/news/science/1113356748/orangutans-manipulate-their-voices-to-scare-predators-032115/