Red-crowned cranes walk at the Zhangye National Wetland Park in Zhangye, northwest China's Gansu Province, June 11, 2018. (Xinhua/Chen Li)

　　Red-crowned cranes walk at the Zhangye National Wetland Park in Zhangye, northwest China's Gansu Province, June 11, 2018. (Xinhua/Chen Li)

　　Red-crowned cranes walk at the Zhangye National Wetland Park in Zhangye, northwest China's Gansu Province, June 11, 2018. (Xinhua/Chen Li)

　　A red-crowned crane walks at the Zhangye National Wetland Park in Zhangye, northwest China's Gansu Province, June 11, 2018. (Xinhua/Chen Li)