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Page last updated at 08:48 GMT, Thursday, 28 April 2011 09:48 UK
Bonobos 'chat' about good foods
By Ella Davies
Earth News reporter

Bark and peep for a kiwi

Bonobos communicate where to find their favourite food using barks and peeps, scientists have found.

In the first study of its kind, researchers in the UK found the apes gave each other specific details about food quality.

The combination of five distinct calls into sequences allowed others to concentrate their foraging around areas known to contain preferred kiwi fruits.

Scientists say the evidence suggests an extensive intelligence in the species.

These animals are highly intelligent and this kind of study highlights their ability to extract meaning from listening to each other's vocalisations
Dr Zanna Clay

Bonobos grunt when they encounter food, in a similar way to their close cousins chimpanzees, as a way of communicating their find to the group.

In these situations however, bonobos are also known to give four more distinct calls.

Scientists from the University of St Andrews, Scotland wanted to test whether bonobo vocalisations were a reliable indicator of food quality.

"We always suspected that bonobos may be able to understand something from listening to each others vocalisations, but so far, nobody had done an experiment to test it," said primate expert Dr Zanna Clay.

They recorded the calls made by the apes at Twycross Zoo, UK when they encountered kiwi fruits and apples in their enclosure.

Researchers found that when the bonobos discovered their preferred food, kiwis, they emitted higher pitched long barks and short "peeps".

When the bonobos found less-preferred apples they made lower pitch "peep-yelps" and yelps.

The primates made these calls in sequences which the researchers recorded and played back to others.

Scientists observed that the successive foragers were then able to direct their search to specific locations after listening to the calls.

When the calls were less acoustically distinct, the foraging activity was more confused, the researchers report in the journal PLoS One.

However, the foraging bonobos were observed making much more effort at sites communicated with high-preference calls in order to find their favourite kiwis.

Scientists point to this behaviour as evidence that the call sequences convey meaning about the quality of food in a specific location.

"These animals are highly intelligent and this kind of study highlights their ability to extract meaning from listening to each other's vocalisations," said Dr Clay.

Dr Clay explained that although bonobos' communication is not comparable to that of humans, their listening skills are remarkable.

Banya, a bonobo involved in the study (c) Zanna Clay
Banya was one of the bonobos involved in the study

"Although we found that the bonobos produce sequences of calls, the way they produce them is unlike syntax in language, or how we structure words and sentences together in strings," she said.

"However, the way that the listening bonobos interpreted these sequences as meaningful shows some similarities with how we listen to language and understand it."

Together with chimpanzees, bonobos are man's closest living relatives and both have large brains in comparison to their body size.

Unlike chimpanzees however, male bonobos do not engage in aggressive raids on neighbouring territories.

The species are also known as the "emotional" apes for their use of peaceful communication, particularly sexual contact, to diffuse community disputes.

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