A border police officer introduce to visitors about red-crowned cranes and how to protect them at Yancheng Coastal Wetlands, a national nature reserve, in Yancheng, Jiangsu province, Dec 11, 2013. Yancheng's border police have been deployed in such areas over the past 30 years to protect wetland and wild birds, earning praise from local people. [Photo by Zhang Shanyu / for China Daily]