Migratory birds seen in NW China's Gansu as weather warms up

A white swan flies on the Xiaosugan lake wetland in Kazak Autonomous County of Aksay, northwest China's Gansu Province, April 5, 2019. Migratory birds like white swans, black-necked cranes and bar-headed geese are seen here as the weather warms up. (Xinhua/Chen Bin)