Birds fly over the Nandagang wetland in Cangzhou, north China's Hebei Province, June 14, 2017. In recent years, local government carried out the ecology recovery work in the Nandagang wetland in Cangzhou. (Xinhua/Liu Jie)
Black swans swim in the water at the Nandagang wetland in Cangzhou, north China's Hebei Province, June 10, 2017. In recent years, local government carried out the ecology recovery work in the Nandagang wetland in Cangzhou. (Xinhua)
Tourists watch birds on the Nandagang wetland in Cangzhou, north China's Hebei Province, June 14, 2017. In recent years, local government carried out the ecology recovery work in the Nandagang wetland in Cangzhou. (Xinhua/Liu Jie)
Birds fly over the Nandagang wetland in Cangzhou, north China's Hebei Province, April 2, 2016. In recent years, local government carried out the ecology recovery work in the Nandagang wetland in Cangzhou. (Xinhua)
Tourists watch red-crowned cranes on the Nandagang wetland in Cangzhou, north China's Hebei Province, May 8, 2014. In recent years, local government carried out the ecology recovery work in the Nandagang wetland in Cangzhou. (Xinhua)
Tourists take a boat on the Nandagang wetland in Cangzhou, north China's Hebei Province, July 2, 2012. In recent years, local government carried out the ecology recovery work in the Nandagang wetland in Cangzhou. (Xinhua)
Tourists watch birds on the Nandagang wetland in Cangzhou, north China's Hebei Province, June 14, 2017. In recent years, local government carried out the ecology recovery work in the Nandagang wetland in Cangzhou. (Xinhua/Liu Jie)
