We continue the third season of our Tides of Change series, along China's coastlines. Over the past four decades, the eastern coast of China has expanded, creating mudflats, another type of coastal wetland and a haven for wildlife. In Jiangsu Province, more than 400 species of birds stop at a wetland in Yancheng before flying south for the winter. And an animal once on the brink of extinction is now thriving. Our reporter Zhou Jiaxin takes us there.

Li turned himself into an avid nature photographer when he first encountered a rare but beautiful bird species on this mudflat 12 years ago.

LI DONGMING Nature Photographer "There was a whole month when I drove there every early morning and spent hours photographing it. I drove 10,000 kilometers that month alone."

En route from northern Russia to southern Asia, millions of migrating shorebirds would stop over this Yellow Sea region, where Li says the spoon-billed sandpiper has been a star because of its rarity.

LI DONGMING Nature Photographer "There are only around 200 pairs in China and 500 worldwide – it's a critically endangered species."

So Li found his way to help – by photographing banded sandpipers – he could help with scientific tracing.

When UNESCO experts inspected the bird sanctuaries in Yancheng, they also recognized Li's photo collections.

In 2019, it was included in the UNESCO list of world heritage sites. The wetland is not just a newly restored wonderland for birds, but also for another species.

ZHOU JIAXIN Yancheng, Jiangsu Province "Milu deer had disappeared in China for more than half a century and were globally endangered. In 1986, China reintroduced 39 of them from the United Kingdom to this wetland on its east coast. Before long, life found a way."

LIU BIN Forestry Researcher Dafeng Milu Deer National Nature Reserve "The total number now has grown to 6,119, thanks to efforts through decades. We began releasing some selected to the wild in 1998, that number in the wild has reached 2,658."

Liu and his team are monitoring and safeguarding the Milu deer in the wild. The deer's habits have opened up another study into an interesting ecosystem that nurtures biodiversity.

LIU BIN Forestry Researcher Dafeng Milu Deer National Nature Reserve "As the wild Milu deer grows, they graze and tread on an invasive cordgrass meant to protect and expand tidal zones. So, the wetland is exposed and grants more space for waterfowl to inhabit."

That gives hope to the photographer, snapping the success of their efforts in the next migration seasons. Zhou Jiaxin, CGTN, Yancheng.