Birds return home

The increasing number of creatures and improved ecological environment have attracted flocks of birds to the reserve and some have settled there permanently, said Zhou.

The Yellow River estuary migratory bird sanctuary was listed as a World Natural Heritage site by the United Nations Educational, Scientific and Cultural Organization in July.

As the ecological environment improves, the Hukou Waterfall area on the Yellow River in Shanxi province has also transformed into a "bird paradise". Species such as black storks, herons, egrets, black-winged stilts, and geese have become the subjects of photographer Lyu Guiming.

The 52-year-old grew up along the banks of the Yellow River. He has been taking photos while working at the waterfall scenic area for over two decades.

"This is a photo I took of the Hukou Waterfall in 2005, with very turbid water; and this one was taken in 2015, where the water flow is noticeably clearer," said Lyu.

"The ecological environment here has substantially improved during the past years," he added.