He found out that they were Baer's pochards, a species under first-class State protection. Less than 2,000 of the birds are estimated to exist.

Zhu's pond is an important breeding area for the species in Wuhan. It's possible they are attracted by the depth and quality of the pond's water, its plants and plankton, as well as the lotus leaves under which they can hide, the bird watchers told him. To date, 10 nests have been found.

The association asked Zhu whether he would agree to let them install surveillance cameras and infrared cameras to record the birds.

"I was worried he would say no, because the ducks could compete for food with the crayfish and affect his earnings," said Yan Jun, president of the association.

But Zhu immediately agreed, saying that the birds "only eat a small amount of food and the loss is acceptable".

As a child, he used to shoot birds with a slingshot, but now, as a member of the bird-watching association, he observes and takes photos of Baer's pochards every day, and has developed a deep affection for them.

He logs the camera results in a notebook: "On May 21, a mother duck played with 10 ducklings and rested on lotus leaves"; "On June 2, a mouse attempted to steal eggs from a nest but failed"; "On June 4, a yellow weasel ate the only two eggs left in a nest".

"It's a shame that the eggs were eaten, but this is natural law and we shouldn't intervene," Zhu said, adding that he was also impressed by the sight of ducklings hatching.

During last year's breeding season between April and August, the birds built 10 nests and laid 99 eggs. In the end, 73 ducklings were born, and Zhu now checks the area in the morning and at night to make sure no one hunts or disturbs the ducks.