White swans fly over the Sanmenxia Yellow River wetland on Nov 25, 2013. A large flock of white swans from Siberia migrates to the Sanmenxia Yellow River wetland in China's Central Henan province for the winter, turning the area into an actual swan lake. With the development of the eco-system in the Yellow River wet land, an increasing number of swans come here to spend winter. Photos: Xinhua

White swans in the Sanmenxia Yellow River wetland in China's Central Henan province on Nov 25, 2013. A large flock of white swans from Siberia migrates to the Sanmenxia Yellow River wetland in China's Central Henan province for the winter, turning the area into an actual swan lake. With the development of the eco-system in the Yellow River wet land, an increasing number of swans come here to spend winter.

White swans in the Sanmenxia Yellow River wetland in China's Central Henan province on Nov 25, 2013. A large flock of white swans from Siberia migrates to the Sanmenxia Yellow River wetland in China's Central Henan province for the winter, turning the area into an actual swan lake. With the development of the eco-system in the Yellow River wet land, an increasing number of swans come here to spend winter.