In my behavioral science study, I am analyzing tool use, as well as postures and gestures. In my initial research, to get some background on chimpanzee behaviors, I learned that chimpanzees typically screech, or squeak, when respectfully greeting a dominant individual. However, I also came across the idea that this also happens when they have fear or are in danger. I have not found information on how to tell the difference in tones in order to differentiate the scenarios. Does anyone have any background on this that they could share? I am interested in knowing if there is a way to tell the difference because I have heard quite a few screeches in my research, thus far.
Hi there,
Chimp screams are quite difficult to tell apart and you are right about subordinates screeching at times to dominants (especially when they are displaying towards them) as well as screeching/screaming when in fear because this is a similar context. It is very hard to tell these two apart and they in fact may mean more or less the same thing. Here is one study where screams and their acoustic properties were looked at in close detail which may be helpful if you are doing acoustic analysis. http://www.pnas.org/content/104/43/17228.short (pdf available online free if you google it). There are also copulation screams produced by females but these sound quite different from the ones given in fear (you can find papers on that too online) and I do not know of any with detailed acoustic analysis. I would caution against trying to make arbitrary divisions based on what you hear and instead to focus on the behaviour and social context you observe when the scream is made to help you differentiate between scream 'types'.
Good luck and hope that helps!
I appreciate your quick response! Thank you for providing this information; it is definitely helpful. You make a good point in not trying to make arbitrary divisions based on sound but social context behavior, instead. In doing that, I have noticed a evident difference in how the chimpanzees tend to behave when, it appears, they are in danger.
Again, thank you for your response and information.
Interestingly, female chimps who wish to mate with lower ranking males have been known to sneak off with them and suppress copulation screams. I've heard it referred to as klepto-copulation.
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ChimpAndSee