White swans are seen at the Yellow River wetland in Sanmenxia, central China's Henan Province, Jan. 5, 2013. (Xinhua/Wang Song)
White swans are seen at the Yellow River wetland in Sanmenxia, central China's Henan Province, Jan. 4, 2013. (Xinhua/Wang Song)
White swans are seen at the Yellow River wetland in Sanmenxia, central China's Henan Province, Jan. 4, 2013. (Xinhua/Wang Song)
White swans are seen at the Yellow River wetland in Sanmenxia, central China's Henan Province, Jan. 5, 2013. (Xinhua/Wang Song)
White swans are seen at the Yellow River wetland in Sanmenxia, central China's Henan Province, Jan. 5, 2013. (Xinhua/Wang Song)
White swans are seen at the Yellow River wetland in Sanmenxia, central China's Henan Province, Jan. 5, 2013. (Xinhua/Wang Song)
White swans are seen at the Yellow River wetland in Sanmenxia, central China's Henan Province, Jan. 5, 2013. (Xinhua/Wang Song)
White swans are seen at the Yellow River wetland in Sanmenxia, central China's Henan Province, Jan. 6, 2013. (Xinhua/Wang Song)
White swans are seen at the Yellow River wetland in Sanmenxia, central China's Henan Province, Jan. 5, 2013. (Xinhua/Wang Song)
White swans are seen at the Yellow River wetland in Sanmenxia, central China's Henan Province, Jan. 6, 2013. (Xinhua/Wang Song)
White swans are seen at the Yellow River wetland in Sanmenxia, central China's Henan Province, Jan. 6, 2013. (Xinhua/Wang Song)