Scientists have been stunned after macaques in Malaysia ate so many rats on palm oil plantations that chemical pest control may no longer be needed.

Pig-tailed macaques had previously been considered a pest themselves as they eat palm oil fruits.

But researchers, who have been studying the animals since 2016, now believe they more than make up for that by eating large numbers of rats, which are a worse pest.

Nadine Ruppert, of Universiti Sains Malaysia, said: "I was stunned when I first observed that macaques feed on rats in plantations.

"I did not expect them to hunt these relatively large rodents or that they would even eat so much meat. They are widely known to be frugivorous primates who only occasionally feast on small birds or lizards."