Swans are seen at a shoal of the Yellow River in Hangjin Banner, north China's Inner Mongolia Autonomous Region on April 2, 2019. (Xinhua/Liu Lei)
Swans are seen at a shoal of the Yellow River in Hangjin Banner, north China's Inner Mongolia Autonomous Region on April 2, 2019. (Xinhua/Liu Lei)
Swans fly above a shoal of the Yellow River in Hangjin Banner, north China's Inner Mongolia Autonomous Region on April 2, 2019. (Xinhua/Liu Lei)
Swans fly above a shoal of the Yellow River in Hangjin Banner, north China's Inner Mongolia Autonomous Region on April 2, 2019. (Xinhua/Liu Lei)
Swans are seen at a shoal of the Yellow River in Hangjin Banner, north China's Inner Mongolia Autonomous Region on April 2, 2019. (Xinhua/Liu Lei)
Swans are seen at a shoal of the Yellow River in Hangjin Banner, north China's Inner Mongolia Autonomous Region on April 2, 2019. (Xinhua/Liu Lei)