Black-headed gulls migrate to Kunming in China's Yunnan

People view flying black-headed gulls at Daguan River in Kunming, southwest China's Yunnan Province, Oct. 31, 2018. Thousands of black-headed gulls have migrated to the city during these days. Kunming is known as the "spring city" for its mild climate and year-round green environment. (Xinhua/Lin Yiguang)