long-tailed macaque monkeys in bali have learnt the value of tourists' possessions, systematically relieving them of the higher-value items to trade back for food. adults are better than juveniles  

original article: Leca et al., 2021 (Philosophical Transactions of the Royal Society of London, B: Biological Sciences), reported in: The Independent by Samuel Osborne on 26th January 2021

this story was in episode 2 #macaque #thief #barter #bali #tourism

the error bar says

around 350 long-tailed macaques live near the Uluwatu Temple in Bali; the temple staff feed them fruit and vegetables daily, but they also steal from and trade with the 1.5 million visiting tourists each year.

for nearly a year, the macaques were videod by two researchers, starting recoding when the monkey looked at and approached a tourist holding or wearing an inedible object likely to be stolen - glasses, flipflops, cell phones. these would soon be traded back for food with the temple staff.

juvenile monkeys got 40% of their targets, increasing to 70% in experienced adults. the items stolen did not correlate with their local availability, suggesting the monkeys were being choosy. they got increasingly-choosy with age, rejecting more of the lower-value items as they reached adulthood.

do monkeys know the cost of everything?

this is a simple story of primate versus primate.

the graphs and the numbers don't quite match, and they don't say where the error bars come from - tut tut - but otherwise this is a straightforward report - monkeys seem to learn much from tourists. i suspect that the temple staff are in on the game too.


hold my banana


The Independent: fact - scientific story reported well