An increasing number of migratory birds, including some species on the endangered list, are overwintering at the Chongming Dongtan Nature Reserve, an important avian habitat on an island in the Yangtze River estuary.

Located to the north of Shanghai, Chongming is China's third-largest island, after Taiwan and Hainan. Overdevelopment of the river in recent decades has had a disastrous effect on the local ecosystem, so Chongming has made ecology a priority. It is aided by the municipal government, which is actively promoting environmental protection, energy conservation and sustainable development.

As of mid-January, 28,264 birds from 43 species had been tracked arriving at the 242-square-kilometer reserve on the eastern end of the island, treating it either as a brief stopover during migration or as a winter base, according to official data.

This winter, a number of protected species, such as hooded cranes, common cranes, whistling swans and rare Chinese mergansers that had long disappeared from the region, have shown up on the wetland.

The broader picture shows that 290 species have been tracked on Dongtan, and more than 300,000 birds shelter there every year, which activists attribute to the high level of eco-protection at the reserve and on the island generally.

In the next three years, 10 billion yuan ($1.6 billion) will be spent to construct reservoirs, revamp the water supply, build drainage facilities and construct flood-control systems in rural areas.

To protect biodiversity in the Dongtan Nature Reserve, the regional authorities have been working on wetland restoration and weeding out harmful, nonnative plants, educating the public and cracking down on poaching.

Jin Weiguo, 56, a rural resident of Chongming, has been protecting the birds at the reserve for more than a decade.

"When I was a child, the birds in the region blotted out the sky and the land, but the number gradually shrank, so I gave up illegal hunting and started protecting the birds, as advocated by the government," he said.

Pan Yixuan contributed to this story.