With the temperature going up and snow and ice melting, more than 310 endangered black storks, along with tens of thousands of other migrantary birds, have arrived at the Gahai Wetland in northeastern Gansu Province.

"With the blue sky, snow mountains, green water, birds as well as their pleasing twittering, Gahai Lake is a heaven on earth," said Zhang Yong, deputy stationmaster of the Gahai Protection Station of the Gansu Gahai Zecha National Nature Reserve Bureau.

Photo taken on March 25 shows black storks are flying over the Gahai Lake in Gahai Zecha National Nature Reserve in northwest China's Gansu Province. With the temperature going up and snow and ice melting, more than 310 endangered black storks, along with tens of thousands of other migrantary birds, have arrived at the Gahai Wetland in northeastern Gansu Province. (Xinhua Photo)

As it is getting warmer and the ice surface of the lake started to shrink, the number of birds returning to the region increases steadily. By now, there are about 15,000 migratory birds around the Gahai Lake and neighboring areas, according to statistics by the protection station.

Black storks are big wading birds and a wildlife under first class special state protection. Due to their rather small population, they have also been listed as an endangered specie in the Convention on International Trade in Endangered Species of Wild Fauna and Flora.

In recent years, the Gahai Zecha nature reserve has been observing black storks constantly.

Photo taken on March 25 shows black storks are looking for food by the Gahai Lake in Gahai Zecha National Nature Reserve in northwest China's Gansu Province.  (Xinhua Photo)

Statistics have shown the number of black storks visiting the Gahai Lake has been rising year on year. Before 2004, there were less than 10 of them; by 2007, up to 130．In 2008, the number was more than 170.

The birds migrate to Gahai in March or April every year to mate and continue their journey in the last ten-day period of October. Zhang said the birds, gathering in the swamp in the center of Gahai wetland, have entered the time for courtship.

Located in the Gannan Tibetan Autonomous Prefecture, Gansu Province, Gahai Zecha National Nature Reserve is a major conservation of water source in the upper reaches of the Yellow River. About 3,470 meters above sea level, the Gahai Lake lies in the key area of the nature reserve and is the biggest fresh water lake on the Qinghai-Tibet Plateau. Rare birds like black storks, black-neck cranes all tend to inhabit by the lake.

The improving of the eco-environment around the Gahai Lake and neighboring wetland contributes mainly to the increasing number of black storks and other migratory birds.

In 2003, the Gahai Zecha National Nature Reserve was formally set up. The almost-dry Gahai Lake, covering 2,174 ha, regained its vitality after it became filled with new water.