JINAN－Dubbed the "mother river" and China's second longest waterway, the Yellow River is attracting more wild birds to the delta.

A growing number of wild birds have taken shelter at the Yellow River Delta National Nature Reserve, located at the river's estuary in East China's Shandong province, thanks to the restoration work on the region's natural environment over the past two decades.

The reserve stretches for about 153,000 hectares. With wetlands making up more than 70 percent of its total area, it is an important wintering and stopover site for migratory birds.

Zhao Yajie, a researcher at the reserve, says 324 oriental white storks, an endangered species, were born on the reserve this year.

The oriental white stork is a migratory bird under first-class national protection in China and listed as endangered by the International Union for Conservation of Nature.

The reserve has seen the birth of over 2,200 oriental storks since 2003 when the birds first nested and bred there, Zhao says.

The number of bird species in the reserve has doubled to 371 from 187 in 1992, when the reserve was first established, according to Liu Jing, an officer at the site.

The conservation area has also seen a surge in the population of Saunders's gulls since the species was first spotted in the region in 1992.

Saunders's gulls are often regarded as an indicator of wetland ecological changes due to the strict requirements the bird has for its breeding sites.

More than 10,000 Saunders's gulls visited during this year's breeding season, according to an earlier field survey.

"The increasing number of endangered species in the reserve proves there has been a significant improvement of the ecological environment in the delta," says Zhao.

Numerous wetland restoration projects, including replenishing water and turning farmland back to wetlands, have been implemented in the region.

A total of 160 million cubic meters of water was supplied to the reserve this year to replenish groundwater and slow down seawater encroachment, according to a local government report released this year.

Water replenishment, inaugurated in 2008, helps restore the wetlands and create a better living environment for both fish and birds.

Xu Mingde, head of the reserve management committee, says that the wetland area of the reserve has increased by 12.3 percent, or 188 square kilometers, since 2017.

There are 1,630 species of wild animals and 685 species of plants monitored in the park, Xu adds.

A national park which consists of eight protected areas, including the Yellow River Delta National Nature Reserve, will be built in the region, according to the provincial department of natural resources.