Tundra swans fly over the Liaohekou National Nature Reserve, northeast China's Liaoning Province, March 19, 2017. The reserve is the rest place where the birds migrate to the north. (Xinhua/Pan Yulong)
Tundra swans fly over the Liaohekou National Nature Reserve, northeast China's Liaoning Province, March 19, 2017. The reserve is the rest place where the birds migrate to the north. (Xinhua/Pan Yulong)