YINCHUAN－On the edge of the vast Maowusu Desert in the Ningxia Hui autonomous region, salt lakes dot the sandy expanse.

The lakes were formed by clean industrial water discharged from nearby collieries owned by Ningxia Coal Industry Group, a subsidiary of State-owned China Energy.

However, in recent years the lakes near Lingwu have become a haven for migratory relict gulls from early April to late August.

The black-headed, red-beaked birds were discovered in the 1970s and recognized as a new species. In 2000, they were placed on the International Union for Conservation of Nature's Red List of Threatened Species. China gives the gulls class one protection for wild animals.

In Ningxia, the rare birds were first seen in 2016.

The gulls love to rest on the islets that dot the lakes. The breeding season is underway and some chicks have already hatched. To protect their offspring, the adult gulls cover their nests most of the time.

"In May 2016, the staff members of Ningxia's wetland protection and management center found more than 800 relict gulls at the lakes beside the coal mines in the Maowusu Desert," said Wei Hong, who works at the center. "It was the first time the gulls were recorded in Ningxia."

The gulls have very specific requirements for their habitat. They like resting on open plains and islets in salt lakes where they can feed on aquatic insects and breed.

"The salt lakes here are formed by water from the mines and they are perfect for the gulls. There is little human interference," Wei said. "After we discovered their existence, we sent people to conduct routine patrols."

For the coal company, the arrival of the birds was both a surprise and added responsibility.

"We never thought that mine water would attract the rare birds, and we need to protect their habitat," Li Baoqiang, from Ningxia Coal, said.

"We supervise the quality of the mine water we discharge, and we also pay attention to the water levels in the lakes so that the islets stay above water."

According to Wei, the environment for the birds is so good that the number of gulls has rapidly increased.

This year, company employees have observed more than 3,800 relict gulls. Other birds, such as whooper swans, shelducks and black-winged stilts, have also flocked to the small islets. The bird paradise has attracted bird watchers from across China.

However, the earth beneath the lakes still has coal deposits and mining will continue for the foreseeable future. Last year, under the guidance of the regional wetland protection and management center, Ningxia Coal began developing a wetland park not far from the lakes to help keep the gulls in the area.

"The company discharges the mine water, which has formed a wetland of more than 1,333 hectares," Li said.

"We developed the water project and grew a tree belt 5 kilometers long and 20 meters wide."

A wetland park management center was also established.

Li, who worked as a miner before, is now tasked with protecting the birds with the help of 20 mine workers. "Surveillance equipment has been installed around the wetland, and we take turns patrolling the area to prevent poaching or damage to the environment," he said.

Li said as he comes into contact with the birds so frequently he has developed a bond with them.

"Patrolling under the sun every day is not easy, but it makes me happy to see that the environment is getting better and the number of birds is increasing," he said.

Xinhua