Thirty whooper swans have recently been spotted frolicking around the Qinghai Lake, making the Qinghai Lake a "swan lake".

Wu Yonglin, head of the Protection Division of the Management Bureau of the Qinghai Lake Natural Reserve, said that these swans came to Qinghai Lake for hibernation earlier than previous years.

Whooper swans swim at Qinghai Lake near Xining, capital of northwest China's Qinghai Province Oct. 6, 2009. Whooper swans arrived at the lake to live through the winter weeks earlier than past years, photo from Xinhua.

He added that the number of the swans spotted there has risen sharply, which is closely related to the improved ecological environment in the region.

He said, "In recent years, the water level of the Qinghai Lake has risen, the area of wetlands has expanded and the number of aquatic animals has increased. All this has provided good conditions for swans' inhabitation and reproduction."

He Yubang, deputy director of the Management Bureau, said, "Last year, 4,275 swans came here for hibernation and more swans are expected to come this year."

The whooper swan, a bird species under the second-class state protection, usually breeds in northern China and Russia's Siberia in spring and autumn. The 4,500-sq m Qinghai Lake, the largest inland salt water lake in China, attracts an estimated 100,000 migratory birds to come for inhabitation and reproduction every year.