A flock of migratory birds hover over Caohai Lake in Weining, southwest China's Guizhou Province, Dec. 12, 2009. Visitors and photographers from all around China is attracted to the 45-sq-km lake as is held at the water venue at 2,200 meters above the sea level that serves as a winter habitat for over 100,000 migratory birds of 200 plus specie including over 1,000 black-necked cranes. (Xinhua/Qin Gang.[Xinhua/Qin Gang]