The Tibetan macaques are frequent visitors to a feeding place where a patrol team member drops food for them in the Dagu Glacier Scenic Area. [Photo by Xu Lin/China Daily]

Tourists enjoy feeding and snapping photos of the creatures.

Zheng joins colleagues on a weekly two-day patrol.

They bring their own food and water to camp while patrolling to monitor wildlife and check for fires.

He feeds the monkeys about 50 kilograms of corn, fruits and vegetables a day.

And Zheng speaks their language.

He summons them by mimicking their calls in the morning. They answer.

They often arrive between 8 am and 10 am and leave at sunset.

It took him about six years to win their trust. Their population has grown from about 70 to 200.

The monkeys previously lived on top of a mountain.

He moved the feeding place further from the peak every few months until they started coming to the current location.