BEIJING,Feb.3, Xinhua - Wetland keeper Yi Feiyue is seeing fewer greater white-fronted geese (Anseralbifrons) than he once did.

Yi, 45, has been working in the East Dongting Lake National Nature Reserve Administration, in central China's Hunan Province, for 19 years.

Spread over the central-lower Yangtze Plain, China's second largest fresh water lake is an ideal habitat for water birds. Every year, at the end of September, more than 100,000 birds winter here after a long journey from the north.

Yi, who sees himself as a guardian of the birds, watches them through his binoculars.

But the declining numbers of greater white-fronted geese tell him something is wrong with the wetland: "Five years ago, I saw this bird almost every day, but in the past two years I've seen them only once a week."

Scientists have also noticed the trend. They blame dam building on Yangtze River, which has lowered Dongting Lake's water levels in the autumn.

That causes the mud flats to appear early and the reed-like sedge plant to sprout sooner. The greater white-fronted geese live on the sprouts, which are too long when the birds eventually arrive, says Cao Lei, a researcher with the Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences.

"Water birds are the indicator of the wetland ecosystem. The decrease in greater white-fronted geese shows the lake is becoming drier and the wetland is dying," Cao adds.

According to the "China national biodiversity conservations strategy and action plan" published in 2010 by the national environmental watchdog, China's grassland and wetland ecosystems are degenerating quickly.

In order to better protect water birds and wetland ecosystems, the State Forestry Administration and World Wide Fund for Nature (WWF) initiated the fourth water birds field survey along the middle and lower Yangtze Plain, including Dongting and dozens of other lakes. Surveys were previously conducted in 2004, 2005 and 2011.

"We are going to count the actual number and species of water birds and, at the same time, get to know the condition of their habitat," says Jiang Yong, senior manager of WWF's Yangtze Project," then we will conduct a comparative study of the four surveys."

Yi Feiyue is on the survey team. "Birds are sensitive. You should keep a distance of at least 200 meters or they will fly away," he says.

He can identify birds from observing their posture when swimming, flying, eating or resting, or from their calls. If a flock of birds flashes across the sky, he instantly recognizes them.

Yi is also good at counting birds. He first gauges the total number and ratio of different species in a large group of birds. "If the birds haven't flown away by then, I will count them one by one, from the minority species," he says. In the three-day survey, he counted 37,719 birds in an area of 20,000 hectares.

The seemingly boring job is full of surprises. Two months ago, he came across a pelican on his daily patrol. "That's exciting because the pelican disappeared from this area nearly 10 years ago," Yi says.

China's economic miracle of the last three decades has come at the expense of the environment and resources. Now that people are seeing the impact of that deterioration, they are starting to reflect. The idea of sustainable development is taking root in daily life.

In the past, residents around Dongting Lake "drained the pond to catch the fish," and many water birds were poisoned and sold to restaurants, says Zhao Qihong, director of the East Dongting Lake National Nature Reserve Administration.

But such behavior is now rare. In the centers of national nature reserves, hunting, fishing and dredging are prohibited, and ecological economy business models, such as organic aquaculture and ecological tourism, are being established in the buffer zone, Zhao adds.

According to experienced birdwatcher Zhong Jia, the number of ornithologists in China has risen from 600 in 2000 to more than 20,000 in 2010 and more than 40 bird-watching groups exist.

Lei Jinyu, 34, has travelled through all China's bird habitats over the past 15 years. "There are 1,435 species of birds in China, and I've seen 962 species," he says. He keeps a notebook of the birds he has seen. "When I watch birds through my binoculars, I enter a wonderland."

As the wetland and water bird protection manager of the Yangtze Project, Lei has turned his hobby into career.

"Like Lei, these enthusiastic birdwatchers will play an important role in protecting the ecosystem," says Jiang Yong. "But legal protection is still needed."

During a meeting of the National Commission on Conservation of Biodiversity in Beijing in December last year, Vice Premier Zhang Gaoli asked authorities to advance legislation on the protection of nature reserves.

He said the government would launch several major projects in this area and set biological diversity protection as an index for evaluating local government performance.

This is what Jiang expects - the administration of nature reserves to be guaranteed by law.

"Protecting birds is protecting people. More birds means clearer water, healthier food and a better living environment," Yi says. He hopes more people take part in bird and wetland protection: "Maybe someday a large flock of greater white-fronted geese will fly back."