The Qinghai Lake [Photo/China.org.cn]

Stepping into winter, the white snow and hundred some mile ice-bounded waters make the Qinghai Lake a magnificent sight. Yet, apart from being blessed with this magnificent looking with ice and snow, the Qinghai Lake also witnesses the "tender passion" of the migrant birds. There are hundreds, even more than a thousand, whooping swans springing and cruising just above the lake surface, solemnly and elegantly, composing the most beautiful "Swan Lake" winter melody under the limpid golden sunshine.

He Yubang, a researcher from the Qinghai Scenic Spot Preservation and Development Office, said, since the monitoring system started to work from 2007 up until now, 2009 was the year that observed the largest number of migrant whooping swans overwintering at the Qinghai Lake. The monitoring data received from Oct. 23 to 27 this year indicates that, there have been 500 swans that arrived at the Qinghai Lake, yet the number of swans will reach a peak value for the whole year this coming January.

Being hailed as "the grand soul of nature", the whooping swan is an animal under first-class national protection. Those whooping swans overwintering at the Qinghai Lake are mostly from the Bayanbulak Lake in Xinjiang, yet they are all overwintering migrant birds. Every year in October, whooping swans from different breeding places start migrating in succession to the Qinghai Lake for overwintering. They will adjourn to their breeding places in late March and early April of the next year when the Qinghai Lake unfreezes.

He Yubang explained that the geographical condition of the Qinghai-Tibet Plateau is very unique. The underground-water almost remains at a constant temperature all year round. The place might look like a world made only of ice and snow yet it possesses a large amount of unfrozen spring water which provides whooping swans an indispensable survival condition.

Located in the eastern part of Qinghai Province, the Qinghai Lake is China's largest salt lake; it is also an internationally important marsh. Swamps, marshes and unfrozen spring water that expand throughout the area make it a heaven for the water birds. In recent years, Qinghai Province has continuously urged efforts for the protection of the eco-system, vegetations and animals in the areas surrounding the lake. As a result, different vegetations in the areas circling the lake have been recovering well, marsh areas have broadened, aquatic organisms have increased, and this all has provided an abundant source of food for the overwintering whooping swans.

However, He Yubang believes that, because the water level of Qinghai Lake has been rising every year, its salinity has reduced. Swamp areas where the swans originally could look for food are gradually being covered with more and more ice, thus reducing their feeding areas and this can lead to an undulation in the number of whooping swans overwintering at the Qinghai Lake.