Swans seen on Yellow River in Qinghai, NW China

Swans are seen at the bank of the Yellow River in Hualong Hui Autonomous County of Haidong City, northwest China's Qinghai Province, Dec. 2, 2020. (Xinhua/Zhang Long)

Swans are seen on the Yellow River in Hualong Hui Autonomous County of Haidong City, northwest China's Qinghai Province, Dec. 2, 2020. (Xinhua/Zhang Long)

Swans are seen on the Yellow River in Hualong Hui Autonomous County of Haidong City, northwest China's Qinghai Province, Dec. 2, 2020. (Xinhua/Zhang Long)

Swans are seen on the Yellow River in Hualong Hui Autonomous County of Haidong City, northwest China's Qinghai Province, Dec. 2, 2020. (Xinhua/Zhang Long)

Swans are seen on the Yellow River in Hualong Hui Autonomous County of Haidong City, northwest China's Qinghai Province, Dec. 2, 2020. (Xinhua/Zhang Long)

Swans are seen on the Yellow River in Hualong Hui Autonomous County of Haidong City, northwest China's Qinghai Province, Dec. 2, 2020. (Xinhua/Zhang Long)