A black swan plays with its five cygnets in a lake at a forest park in Hejing county of Xinjiang Uygur autonomous region in October 31, 2017. (Photo: China News Service/Liu Xueqiang)

A black swan plays with its five cygnets in a lake at a forest park in Hejing county of Xinjiang Uygur autonomous region in October 31, 2017. (Photo: China News Service/Liu Xueqiang)

A black swan plays with its five cygnets in a lake at a forest park in Hejing county of Xinjiang Uygur autonomous region in October 31, 2017. (Photo: China News Service/Liu Xueqiang)