Monkeys patrol the walls of the temple, in the centre of the 800-year-old city, to protect their turf. In March, they staged a brazen raid on another group of monkeys living around the Phra Kan Shrine, on the prowl for temple offerings.
Their invasion – captured in a video that went viral on social media - resulted in a vicious street fight that stopped traffic for ten minutes as the rival gangs screeched, charged at each other and engaged in paw-to-paw combat.
"They're so used to having tourists feed them and the city provides no space for them to fend for themselves," Supakarn Kaewchot, a government veterinarian told Reuters.
"With the tourists gone, they've been more aggressive, fighting humans for food to survive," she said. "They're invading buildings and forcing locals to flee their homes."
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The human population has had to continue with uneasy coexistence as parts of city cede complete control to the monkeys.
An abandoned cinema has reportedly become the primates' headquarters, with the projection room turned into a cemetery where the monkeys lay their dead to rest.
A nearby shop owner said he displayed stuffed tiger and crocodile toys to try to scare off the creatures and prevent them from snatching spray-paint cans.
"We live in a cage but the monkeys live outside," said one resident, Kuljira Taechawattanawanna. "Their excrement is everywhere, the smell is unbearable especially when it rains."
For years, city residents have had a love-hate relationship with their monkey neighbours, who attract tourist dollars but regularly create mayhem, breaking windows, stealing groceries and damaging cars.
But the worsening fights, along with reports of locals barricading themselves in their homes, and no-go zones for humans, have prompted the authorities to intervene, restarting a sterilisation programme after a three year pause.
Wildlife department officers have placed big cages around the city, filling them with fruit to lure the animals inside and then take them to a clinic where they are anaesthetised, sterilised and left with a tattoo to mark their neutering.
They aim to treat hundreds out of the 6,000-strong macaque population within the next few weeks.