ZHENGZHOU — As winter approaches, flocks of swans from Mongolia and Siberia migrate thousands of kilometers to Central China's Henan province before cold currents sweep over the country's north.

The shoal wetland spanning more than 26,000 hectares on the banks of the Yellow River in the city of Sanmenxia is their destination for wintering.

"The first batch of around 30 swans arrived in late October, with many more still to come," said Gao Ruyi, head of the bird-ringing station of the city's swan wetland protection center.

Sanmenxia, home to 2 million residents, has adopted a series of ecological protection measures, such as a sewage water discharge ban and wetland restoration, to provide a better habitat for the wintering birds, including swans.

The swans' habitat in the nature reserve of the wetland was disinfected in early October, before hundreds of volunteers joined forestry and public security department workers for patrolling and monitoring in mid-October. Later that month, vehicles were banned from running on the roads near the wetland to ensure a safe, tranquil environment for the feathered visitors. The traffic ban will last until early March, when swans will head northward.

Zhang Mingyun, head of the city's volunteer association for swan protection, patrols the wetland almost every day during the swans' stay. He observes their behavior, takes photographs and spreads knowledge regarding their protection to residents.

"Being our city's bird, the swan is just like our own child. Locals have a special bond with swans," Zhang said, adding that swan "guardians" like him submit suggestions to relevant government departments every year about swan protection, based on their latest observations.

With the joint efforts of residents and relevant departments, Sanmenxia issued the country's first local regulation on the protection of swans in 2017, and set Nov 22 as "White Swans' Day" every year.

Statistics show the number of wild bird species in the wetland of Sanmenxia has risen from 175 over the past two decades to 315 today. Last year, more than 16,000 swans wintered in Sanmenxia, accounting for more than half the country's total.

Li Changkan, an ornithologist at the Zhengzhou Normal University, said birds are a "barometer" for the wetland's ecology. A sound climate, safe environment and abundant food supplies are important for wintering birds.

"The government's legislative protection and residents' awareness of bird protection have created a safe habitat for birds," Li said.

Xinhua