Little swans are seen at the Donggu Lake wetland of the Quyuan administration area in Yueyang City, central China's Hunan Province, Nov. 23, 2021. About 3,000 little swans have arrived at the Donggu Lake wetland of the Quyuan administration area in Yueyang for wintering. [Photo by Chen Sihan/Xinhua]

Little swans fly over houses in the Quyuan administration area in Yueyang City, central China's Hunan Province, Nov. 23, 2021. About 3,000 little swans have arrived at the Donggu Lake wetland of the Quyuan administration area in Yueyang for wintering. [Photo by Chen Sihan/Xinhua]

Little swans are seen at the Donggu Lake wetland of the Quyuan administration area in Yueyang City, central China's Hunan Province, Nov. 23, 2021. About 3,000 little swans have arrived at the Donggu Lake wetland of the Quyuan administration area in Yueyang for wintering. [Photo by Chen Sihan/Xinhua]

Little swans are seen at the Donggu Lake wetland of the Quyuan administration area in Yueyang City, central China's Hunan Province, Nov. 24, 2021. About 3,000 little swans have arrived at the Donggu Lake wetland of the Quyuan administration area in Yueyang for wintering. [Photo by Chen Sihan/Xinhua]

Little swans are seen at the Donggu Lake wetland of the Quyuan administration area in Yueyang City, central China's Hunan Province, Nov. 24, 2021. About 3,000 little swans have arrived at the Donggu Lake wetland of the Quyuan administration area in Yueyang for wintering. [Photo by Zhao Zhongzhi/Xinhua]

Little swans are seen at the Donggu Lake wetland of the Quyuan administration area in Yueyang City, central China's Hunan Province, Nov. 23, 2021. About 3,000 little swans have arrived at the Donggu Lake wetland of the Quyuan administration area in Yueyang for wintering. [Photo by Chen Sihan/Xinhua]

Little swans are seen at the Donggu Lake wetland of the Quyuan administration area in Yueyang City, central China's Hunan Province, Nov. 23, 2021. About 3,000 little swans have arrived at the Donggu Lake wetland of the Quyuan administration area in Yueyang for wintering. [Photo by Zhao Zhongzhi/Xinhua]

Little swans are seen at the Donggu Lake wetland of the Quyuan administration area in Yueyang City, central China's Hunan Province, Nov. 24, 2021. About 3,000 little swans have arrived at the Donggu Lake wetland of the Quyuan administration area in Yueyang for wintering. [Photo by Chen Sihan/Xinhua]