Monkeys in Indonesia learning to ransom stolen goods for food

June 1 (UPI) -- A group of monkeys living near an Indonesian temple have learned how to ransom items stolen from tourists in exchange for food, researchers said.

The long-tailed macaques living near Uluwatu Temple on the island of Bali have long been the subject of stories and YouTube videos alleging the monkeys steal items such as glasses from tourists and return them only in exchange for food, leading Fany Brotcorne, a primatologist at the University of Liege in Belgium, to study the phenomenon.

"It's a unique behavior. The Uluwatu Temple is the only place in Bali where it's found," Brotcorne told New Scientist.

Brotcorne and her associates, who published their research in the journal Primates, spent four months in 2010 observing the monkeys living near the temple.

The researchers found the two groups of macaques that spent the most time around tourists had the highest rates of "robbing and bartering" behavior, indicating they may have learned the ransoming technique from observing each other.

Brotcorne said she and her associates believe the robbing and bartering is a cultural behavior spread by monkeys observing and copying each other. She said in the years since the observations recorded in 2010 other groups of monkeys in the area have been seen starting to engage in the behaviors.

Brotcorne said her findings have major implications for the study of primate psychology, particularly in how they transmit information between groups, how much they understand their own actions, and how they plan for the future.

"Bartering and trading skills are not well known in animals. They are usually defined as exclusive to humans," she said.

Brotcorne said she nearly became a victim of her own research subjects.

"Oh, so many times," she said. "The monkeys were always trying to steal my hat, my pen, even my research data!"