Chimpanzees change their hunting strategy 27 years after being studied by scientists

For Sonso chimpanzees most of the current generation of adults were born being being watched by scientists so they are relaxed about their presence. Photo / 123RF

It seems humans aren't the only creatures that feel the pressure to perform.

Chimpanzees change their hunting strategy when they know scientists are watching, new research suggests.

Scientists believe a group of Sonso chimps in Uganda who have been observed by scientists for 27 years may have become acclimatised to being watched, while their Waibiri neighbours have not, reports Daily Mail.

This might explain the dramatically different hunting strategies of the Sonso and Waibira chimpanzee communities that live just next to one another.

Research led by the University of St Andrews found that two chimpanzee communities in the Budongo Forest in Uganda had strikingly different attitudes to hunting and how they shared meat.

"The differences in hunting between these communities are dramatic - so we wanted to try to understand why", said lead author Dr Catherine Hobaiter.

"They live in the same forest and have access to the same prey, but they hunt for different species and seem to share food differently", she said.

There are many reasons why their hunting practices are so different, but Dr Hobaiter believes it may be because one group has become acclimatised to being watched by scientists.

"The main thing that's different about them right now is how used to having humans follow them around the forest they are", she told BBC.

"For Sonso - most of the current generation of adults were born with us being there, so they're really incredibly relaxed about our presence."

"But [for] Waibira - some of the young ones have started to grow up and become very comfortable with us, but some of the adults would be 30-40 years old when we started, and five years of us following them round is a fraction of their lifetime", she said.

Dr Hobaiter noted that it might take a long time for chimpanzees to accept the presence of newcomers in their territory.

The Sonso community, studied for 27 years, prefers to hunt for black and white colobus monkeys.

After catching a monkey, the high-ranking males take possession of the carcass, even when they weren't the ones to catch it.

Other group members then beg for access to the food, which is sometimes shared.

In contrast, the Waibira community, studied for six years, currently prefers to hunt for duiker - a type of small antelope - especially red duiker, a species the Sonso chimpanzees have never been seen to hunt.

Waibira also hunt for several other species, including monkeys.

After catching prey, lower-ranking group members, even young females, are able to take and keep possession of the carcass.

"Long-term research with wild chimpanzees brings real conservation benefits, but we have to remember that our presence can affect their behaviour; in this case the group hunting used to catch colobus monkeys may take years to re-establish", Dr Hobaiter said.

"Part of our work is to understand what our impact is and to try to minimise it", she said.

Chimpanzees are widely considered the most "cultural" species of non-human animals.

This study emphasises that cultural, social, environmental and human factors all contribute to the differences we see between chimpanzee communities today, researchers said.

Sonso and Waibira

The Sonso community, studied for 27 years, prefers to hunt for black and white colobus monkeys.

After catching a monkey the high-ranking males take possession of the carcass, even when they weren't the ones to catch it.

Other group members then beg for access to the food, which is sometimes shared.

The Waibira community, studied for six years, currently prefers to hunt for duiker - a type of small antelope - especially red duiker, a species the Sonso chimpanzees have never been seen to hunt.

Waibira also hunt for several other species, including monkeys. After catching prey, lower-ranking group members, even young females, are able to take and keep possession of the carcass.

Dr Catherine Hobaiter believes the presence of scientists might have changed the behaviour of the communities.