People feed black-headed gulls at the Dianchi Lake in Haigeng park in Kunming, capital of southwest China's Yunnan Province, Jan. 11, 2018. (Xinhua/Yang Zongyou)

People feed black-headed gulls at the Dianchi Lake in Haigeng park in Kunming, capital of southwest China's Yunnan Province, Jan. 11, 2018. (Xinhua/Yang Zongyou)

People feed black-headed gulls at the Dianchi Lake in Haigeng park in Kunming, capital of southwest China's Yunnan Province, Jan. 11, 2018. (Xinhua/Yang Zongyou)

People feed black-headed gulls at the Dianchi Lake in Haigeng park in Kunming, capital of southwest China's Yunnan Province, Jan. 11, 2018. (Xinhua/Yang Zongyou)

People feed black-headed gulls at the Dianchi Lake in Haigeng park in Kunming, capital of southwest China's Yunnan Province, Jan. 11, 2018. (Xinhua/Yang Zongyou)

People feed black-headed gulls at the Dianchi Lake in Haigeng park in Kunming, capital of southwest China's Yunnan Province, Jan. 11, 2018. (Xinhua/Yang Zongyou)