Birds' guardian in Caohai(5/10)

Zang Erjun checks the conditions of birds. Zang Erjun, 59, is a ranger in Caohai National Nature Reserve in Weining county, southwest China's Guizhou province. Caohai wetland is the major habitat of China's first class protected animal black-necked cranes. It is also among the list that has most abundant bird resources in China. (Photo: Xinhua/Yang Wenbin)