When chimps have sex with other male chimps around, the female is usually pretty noisy, squeaking and screaming in the throes of passion. That's especially true when the female is doing the dirty with a high-ranking male. Interestingly though, if other female chimps are around, the sex is much quieter. Researchers from the University of St. Andrews recorded the sounds of chimp sex to learn about the sounds of monkey chimp love. From Science News:
The benefit of this strategy could be that she avoids attacks from other females while confusing males about who’s going to be the dad, (University of St. Andrews professor Simon) Townsend and his colleagues propose in the June PLoS ONE.Link
“It’s very elegant and quite novel,” says primatologist Stuart Semple of Roehampton University in London. Previous work focused on male reaction, so documenting the effects of a female audience brings a new dimension to the research. Also the new paper finds no evidence for the standard belief that female calls incite male competition, he says... Townsend argues the females give confusing signals about paternity thus possibly enlisting the support of important males in case other females attack.