A wild yak is seen at the source of the Yellow River section of the Sanjiangyuan National Park in northwest China's Qinghai Province, Jan. 21, 2020. (Photo by Song Zhongyong/Xinhua)

Aerial photo taken on May 25, 2021 shows a view of Ngoring Lake at the source of the Yellow River section of the Sanjiangyuan National Park in northwest China's Qinghai Province. (Xinhua/Li Zhanyi)

A wild wolf is seen at the source of the Yellow River section of the Sanjiangyuan National Park in northwest China's Qinghai Province, Jan. 21, 2020. (Photo by Song Zhongyong/Xinhua)

A herd of Tibetan antelopes are seen at the source of the Yellow River section of the Sanjiangyuan National Park in northwest China's Qinghai Province, Aug. 26, 2016. (Photo by Song Zhongyong/Xinhua)

A Tibetan wild donkey is seen at the source of the Yellow River section of the Sanjiangyuan National Park in northwest China's Qinghai Province, May 25, 2021. 2 (Xinhua/Zhang Long)