Monkeys living near the Uluwatu Temple in Bali, Indonesia, are reportedly openly engaging in theft and ransom against helpless tourists (video below).
The long-tailed macaques have grabbed cameras, cash, eye glasses and hats from folks, which they do not return until the unsuspecting tourists pay a food ransom, according to New Scientist.
Fany Brotcorne, a primatologist at the University of Liege in Belgium, told the news site: "It’s a unique behavior. The Uluwatu Temple is the only place in Bali where it’s found."
Brotcorne and her research team studied four groups of monkeys for four months to learn why they engage in this mafia-like behavior.
She found the two groups of monkeys that spent the most time around tourists were most likely to steal objects and barter for their return.
According to Brotcorne, the monkeys learned this lascivious behavior by watching other monkeys. Her research found that groups with young males were most likely to engage in the theft-and-ransom practice.
Brotcorne believes this type of learned anti-social behavior is likely passed down from generations of monkeys.
She also found a fifth group of monkeys that moved into the area learned their thieving ways from the more experienced crooks.
Serge Wich, a primatologist at Liverpool John Moores University in the UK, said Brotcorne’s study gives a glimpse into "a novel and quite spectacular example of flexibility in primate behavior in response to environmental changes."
"This indicates that it can indeed be a new behavioral tradition in primates and one that teaches us that new traditions can involve robbing and bartering with a different species," Wich added.
Brotcorne hopes her study will help other researchers learn more about how monkeys communicate, how much the primates recognize their own actions and how they prepare for future days.
"Bartering and trading skills are not well known in animals," Brotcorne stated. "They are usually defined as exclusive to humans."
Brotcorne was asked if she was ever the victim of monkey theft, and replied: "Oh, so many times. The monkeys were always trying to steal my hat, my pen, even my research data!"
The New Scientist posted a video of the monkey thefts on YouTube where commenters added their feelings:
"You slick little f***ers..." one person commented.
"It's like if cats had opposable thumbs," another added.
"Looks like people from Detroit and Baltimore have been visiting Indonesia," a third commenter chimed in.
"Now this [behavior] seems to have been established due to the positive outcome of getting food," one person wrote. "I wonder if a negative outcome had been the result if the behaviour would be present or diminished."
"These monkeys need to be given access to better schools and better economic opportunities," another wrote, in a seemingly joking manner. "Don't blame the monkeys for doing this, blame society and the white man."