Animals communicate in many ways and for many reasons. One of the most common reasons an animal communicates is for its own safety. Animals can communicate with members of their own species or even with predators when they sense a threat.
The article "Orangutans Invent Deceptive 'Kiss Squeak'" by Jennifer Viegas for Discovery News discusses a study recently published in Proceedings of the Royal Society B. Researcher Madeline Hardus from the Behavioral Biology Group at the University of Utrecht and her colleagues found that, when threatened, orangutans produce a "kiss squeak" sound that makes them sound larger than they actually are and, therefore, more intimidating.
The researchers recorded wild orangutan kiss squeaks at Central Kalimantan in Borneo, Indonesia. The orangutans can make the sound a few different ways. They can make it themselves with a sharp intake of air through puckered lips or they can modify the call by making it against their hands or using leaves stripped from twigs. This study shows that the orangutans can use a tool to modify the sound and provides evidence as to how and why animals modify calls. The orangutan is the only primate that makes the kiss squeak noise, and this call is the only known modified call made by any primate.
Orangutans sometimes use one hand to make the leaf-modified kiss squeak while using the other hand to throw things at predators, which is evidence that this call is part of a defense mechanism. After analyzing the recordings of kiss squeaks, the researchers found that the hand-modified and leaf-modified calls had lower maximum frequencies than the kiss squeak made using the mouth. The leaf-modified squeaks had the lowest maximum frequencies of the three types and did not change the sound in any other ways. The researchers believe the lower-frequency squeaks are meant to fool predators who can hear but cannot see the orangutan into believing the orangutan is larger than he actually is, since larger animals tend to produce lower-frequency sounds than smaller animals.
The article explains that there have been increasing threats to the survival of orangutan populations over the years. Sumatra and Borneo are the only two islands the orangutan still inhabits. Hardus explains that the modified kiss squeak probably started with one individual through trial and error and eventually caught on with other orangutans as a mode of protection. The study by Hardus et al. proves that orangutans' communication skills are more developed than previously thought.
A link to the Discovery News article "Orangutans Invent Deceptive 'Kiss Squeak'" by Jennifer Viegas is provided below:
Posted by "Sarah Benjamin" (1)
It is quite remarkable that the different frequencies of the same call can communicate various messages to predators. The lower frequency of the calls (hand-modified and leaf-modified) are used when the Orangutan is not seen by the predator to fool the predator into thinking it is a larger animal. But when the call is used in the presence of a predator (higher frequency) is there any body movements or gestures that are associated with the call to further deter predators?
ReplyDeleteEmerson Martin (1)
Is there any sort of reliability to the signal that might actually lead the predator to believe that the Orangutan producing the call is not worth its time? For example, did the researchers find any correlation between the strength and believability of the signal (ability to deter predators) and the condition of the animal?
ReplyDeleteHow did they know that this is a recent adaptation to Orangutan survival strategies? When was the call first recorded?
Very interesting find.
Posted by Deysha Rivera
Who knew orangutans could be so deceptive?! This is a very intelligent modification on behalf of the orangutan species. I agree, they probably devised this deceptive call out of trial-and-error tactics, especially given that they are so rare- deception has become a way to survive.
ReplyDeleteWere there any further studies comparing the lower-frequency calls (signaling that the call came from a larger orangutan) to the higher-frequency calls, and the related success in warding off predators?
Great post!
Posted by Ashley Paon
This article was a great find for a couple of reasons including, evolutionary ideas for why these calls are made and the idea of deceptive signals. As you stated, these animals are threatened, so having signals to ward off predators would be beneficial. This proves that communication signals can evolve through natural selection. The part I find most amazing about this article was that these animals were able to make the decision to not only make this noise for deceptive purposes but also alter it to have a lower frequency.
ReplyDeleteDid this article mention anything about the predators they were deceiving? Or if different frequency sounds were used for different predators? Also was there any mention of the general characteristics of the orangutans making the calls (sex/age)? I would be curious to know if this is something learned or imitated at a young age or something that has become innate.
Posted by Jackie Connolly
Thanks for all the comments; I'll do my best to answer your questions.
ReplyDeleteThe article I read about the study did not give much information about the researchers' study methods, so I do not know if they studied the effectiveness of the squeak kiss. The article did explain that, when the digital recordings were analyzed, the lower frequency was the only difference between the modified call and the normal call. Since larger animals make lower-frequency sounds, it makes sense that the call would be used to trick predators into thinking the orangutan was a bigger threat. The article did not explain whether there was any correlation between the call and the orangutan's age, sex, or size. As far as the orangutans incorporating other gestures to ward off predators, the researchers did observe some of the orangutans throwing objects while making the sound. From the study results discussed in the article, it does seem as if the deceptive call is an adaptation for survival, since it is used in the presence of predators to convince the predators to give up the hunt. The way iStill, I wonder if any other scientists that would argue that the call is used for some other purpose. It would also be interesting to see another study that looks at how the use of the deceptive sound spread through the species to find out if it is innate or learned.
Posted by Sarah Benjamin