Wintering swans forage at a wetland in Dachuan Town of Lanzhou, northwest China's Gansu Province, Jan. 2, 2023. Lanzhou has created more improved habitats for migratory birds in recent years thanks to continuous ecological efforts along the Yellow River. (Xinhua/Chen Bin)

Wintering swans are seen at a wetland in Dachuan Town of Lanzhou, northwest China's Gansu Province, Jan. 2, 2023. Lanzhou has created more improved habitats for migratory birds in recent years thanks to continuous ecological efforts along the Yellow River. (Xinhua/Chen Bin)

Wintering swans are seen at a wetland in Dachuan Town of Lanzhou, northwest China's Gansu Province, Jan. 2, 2023. Lanzhou has created more improved habitats for migratory birds in recent years thanks to continuous ecological efforts along the Yellow River. (Xinhua/Chen Bin)

A wintering swan is seen at a wetland in Dachuan Town of Lanzhou, northwest China's Gansu Province, Jan. 2, 2023. Lanzhou has created more improved habitats for migratory birds in recent years thanks to continuous ecological efforts along the Yellow River. (Xinhua/Chen Bin)

Wintering swans are seen at a wetland in Dachuan Town of Lanzhou, northwest China's Gansu Province, Jan. 2, 2023. Lanzhou has created more improved habitats for migratory birds in recent years thanks to continuous ecological efforts along the Yellow River. (Xinhua/Chen Bin)

Wintering swans are seen at a wetland in Dachuan Town of Lanzhou, northwest China's Gansu Province, Jan. 2, 2023. Lanzhou has created more improved habitats for migratory birds in recent years thanks to continuous ecological efforts along the Yellow River. (Xinhua/Chen Bin)

Wintering swans are seen at a wetland in Dachuan Town of Lanzhou, northwest China's Gansu Province, Jan. 2, 2023. Lanzhou has created more improved habitats for migratory birds in recent years thanks to continuous ecological efforts along the Yellow River. (Xinhua/Chen Bin)

Wintering swans are seen at a wetland in Dachuan Town of Lanzhou, northwest China's Gansu Province, Jan. 2, 2023. Lanzhou has created more improved habitats for migratory birds in recent years thanks to continuous ecological efforts along the Yellow River. (Xinhua/Chen Bin)

Wintering swans are seen at a wetland in Dachuan Town of Lanzhou, northwest China's Gansu Province, Jan. 2, 2023. Lanzhou has created more improved habitats for migratory birds in recent years thanks to continuous ecological efforts along the Yellow River. (Xinhua/Chen Bin)

Wintering swans are seen at a wetland in Dachuan Town of Lanzhou, northwest China's Gansu Province, Jan. 2, 2023. Lanzhou has created more improved habitats for migratory birds in recent years thanks to continuous ecological efforts along the Yellow River. (Xinhua/Chen Bin)