Migratory birds arrive at Longwangtan Park in Lhasa to escape cold

A ruddy shelduck flies near the Potala Palace at the Longwangtan Park in Lhasa, southwest China's Tibet Autonomous Region, Dec. 20, 2019. Many migratory birds, such as bar-headed geese and black-headed gulls, arrived here to escape the cold. (Xinhua/Zhang Rufeng)