Grey herons sit on branches of tree in Zhouwan Village of Shipo Township in Luonan County, Northwest China's Shaanxi Province, June 18, 2019. (Photo: Xinhua)

Grey herons rest on a tree in Zhouwan Village of Shipo Township in Luonan County, Northwest China's Shaanxi Province, June 18, 2019. (Photo: Xinhua)

A grey heron flies back to its nest on a tree in Zhouwan Village of Shipo Township in Luonan County, Northwest China's Shaanxi Province, June 18, 2019. (Photo: Xinhua)

Grey herons rest on a tree during sunset in Zhouwan Village of Shipo Township in Luonan County, Northwest China's Shaanxi Province, June 18, 2019. (Photo: Xinhua)