Cats and monkeys live together in Kunming Zoo, June 27, 2017. [Photo/VCG]

Wang said the rats bred quickly as a result of the abundance of food provided to the monkeys by zookeepers and tourists. Living in small holes on the monkey hill, the rats proved hard to deal with.

Zookeepers tried pouring water down their holes and hitting them with brooms and catapults, but it made little difference.

They also considered poisoning the rats but were worried about harming the monkeys.