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

Aerial photo taken on April 5, 2019 shows migratory birds flying above the Dasugan lake wetland in Kazak Autonomous County of Aksay, northwest China's Gansu Province. Migratory birds like white swans, black-necked cranes and bar-headed geese are seen here as the weather warms up. (Xinhua/Chen Bin)