This photo taken on Dec. 20, 2025 shows swans at a wetland in Sanmenxia, central China's Henan Province. A large number of migratory swans have flocked to the Yellow River wetland in Sanmenxia to spend winter. (Photo by Feng Xiaomin/Xinhua)

People view swans at a wetland park in Sanmenxia, central China's Henan Province, Dec. 20, 2025. A large number of migratory swans have flocked to the Yellow River wetland in Sanmenxia to spend winter. (Photo by Niu Shupei/Xinhua)

This photo taken on Dec. 20, 2025 shows swans at a wetland in Sanmenxia, central China's Henan Province. A large number of migratory swans have flocked to the Yellow River wetland in Sanmenxia to spend winter. (Photo by Zhao Yongtao/Xinhua)

An aerial drone photo taken on Dec. 20, 2025 shows people viewing swans at a wetland in Sanmenxia, central China's Henan Province. A large number of migratory swans have flocked to the Yellow River wetland in Sanmenxia to spend winter. (Photo by Liu Xiaokun/Xinhua)

This photo taken on Dec. 20, 2025 shows swans flying over a wetland in Sanmenxia, central China's Henan Province. A large number of migratory swans have flocked to the Yellow River wetland in Sanmenxia to spend winter. (Photo by Zhao Yongtao/Xinhua)

This photo taken on Dec. 21, 2025 shows swans at a wetland in Sanmenxia, central China's Henan Province. A large number of migratory swans have flocked to the Yellow River wetland in Sanmenxia to spend winter. (Photo by Xu Hongxing/Xinhua)

People view swans at a wetland park in Sanmenxia, central China's Henan Province, Dec. 20, 2025. A large number of migratory swans have flocked to the Yellow River wetland in Sanmenxia to spend winter. (Photo by Zhao Yongtao/Xinhua)

An aerial drone photo taken on Dec. 21, 2025 shows swans at a wetland in Sanmenxia, central China's Henan Province. A large number of migratory swans have flocked to the Yellow River wetland in Sanmenxia to spend winter. (Photo by Wang Gaochao/Xinhua)

This photo taken on Dec. 20, 2025 shows swans at a wetland in Sanmenxia, central China's Henan Province. A large number of migratory swans have flocked to the Yellow River wetland in Sanmenxia to spend winter. (Photo by Li Heng/Xinhua)