Whooper swans look for food on the Liangchenghekou Wetland in Rizhao, east China's Shandong Province, Dec. 13, 2014. More than 50 species of birds came to the Liangchenghekou Wetland to spend winter this year thanks to the local authority's efforts to improve the ecological environment on the wetland in the past years. (Xinhua/Fan Changguo)