The long-tailed macaques at the Uluwatu Temple seem to be aware that humans are more likely to give them food in return for items such as electronics rather than less valuable things like hairpins, said Dr Jean-Baptiste Leca, associate professor in the psychology department at the University of Lethbridge in Canada.

“These monkeys have become experts at snatching them from absent-minded tourists who didn’t listen to the temple staff’s recommendations to keep all valuables inside zipped handbags firmly tied around their necks and backs,” said Dr Leca.

The study of the monkey robbers found they would expect better rewards for higher value items. In one instance negotiations with one of them lasted 17 minutes.

Dr Leca said: “These behaviours are socially learned and have been maintained across generations of monkeys for at least 30 years in this population.”