In a video posted last week, a mob of monkeys runs around a city plaza in Thailand. Something gets thrown in the macaques’ midst and they break into a giant brawl.

This horde of animals lives in Lopburi, home of the country’s Phra Prang Sam Yot monkey temple. The macaques, which are usually fed by tourists visiting the city, are finding a new scarcity because of the coronavirus. And they’re not alone. Large populations of wild animals are sustained almost entirely on treats handed out by tourists in a variety of Asian countries. But over the past few weeks, the flow of tourists has been reduced to a trickle as a result of quarantines, travel restrictions and a general reduction in visitors put in place to stop the spread of the illness.

Now, for better or worse, thousands of animals are being forced to fend for themselves.

Although fights between the macaques of Lopburi are not uncommon, a brawl of the magnitude shown in that video suggests that resources are scarce, said Asmita Sengupta, an ecologist at the Ashoka Trust for Research in Ecology and Environment in Bangalore, India, who studies the effects of humans feeding macaques, which remain wild animals even if they live in close quarters with people.

“The fall in tourist numbers because of Covid-19 may have indeed brought about a shortage of food supply for them,” she said. That shows that feeding the monkeys “can have detrimental effects. Once they get used to being fed by humans, they become habituated to humans and even display hyper-aggression if they are not given food.”