Bachelor baboons eavesdrop on rivals to steal their mates

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The Independent Online

Male baboons have evolved techniques for getting sneaky sex by eavesdropping on neighbouring apes.

Bachelor baboons are able to home in on a female by listening to her grunts and those of her mate and working out how far they are apart. If the distance is big enough, around 40 metres, the unattached baboon takes this as a sign that mating opportunities might be possible and moves in.

"Eavesdropping may be one strategy by which male baboons achieve sneaky matings," say researchers from the University of Pennsylvania. "Male baboons monitor consortships so assiduously that they rapidly recognise both when an unexpected mating opportunity arises and when a consortship has ended."

Males often take over a female within minutes of another male moving out. It has also been reported that male baboons move in when a more dominant and sexually successful male is temporarily away from his partner.

But until now just how bachelor baboons spotted an opportunity with a sexually receptive female had not been clear.

In a series of experiments, researchers played different grunts and copulating noises through speakers to male baboons.

"When male baboons heard a sequence of calls suggesting that a consorting male and his female had temporarily separated, they responded significantly more strongly," says a report of the research in the journal Animal Behaviour this week.

Researchers say the results support the idea that baboons and other monkeys are able to recognise and understand social relationships. They may even be able to appreciate that some relationships just do not last.

"They seem to recognise that different types of relationships are characterised by different patterns of spatial proximity," the researchers added.