Chinese Mergansers, an endangered bird species, swim in a river in Longhu Mountain scenic area in Yingtan, east China's Jiangxi Province, on Dec. 18, 2018. Since about 80 Chinese Mergansers were spotted in the Longhu Mountain scenic area to pass the winter, a series of measures have been taken by local authorities to make sure of the safety of the wintering birds. (Xinhua/Yang Jihong)