Bar-headed geese fly over the Lhasa River, southwest China's Tibet Autonomous Region, Dec. 24, 2017. The populations of bar-headed goose, ruddy shelduck and mallard have increased in Lhasa River. (Xinhua/Zhang Rufeng)
Mallards swim in the Lhasa River, southwest China's Tibet Autonomous Region, Dec. 24, 2017. The populations of bar-headed goose, ruddy shelduck and mallard have increased in Lhasa River. (Xinhua/Zhang Rufeng)
Bar-headed geese fly over the Lhasa River, southwest China's Tibet Autonomous Region, Dec. 24, 2017. The populations of bar-headed goose, ruddy shelduck and mallard have increased in Lhasa River. (Xinhua/Zhang Rufeng)
Birds swim in the Lhasa River, southwest China's Tibet Autonomous Region, Dec. 24, 2017. The populations of bar-headed goose, ruddy shelduck and mallard have increased in Lhasa River. (Xinhua/Zhang Rufeng)
Ruddy shelducks fly over the Lhasa River, southwest China's Tibet Autonomous Region, Dec. 24, 2017. The populations of bar-headed goose, ruddy shelduck and mallard have increased in Lhasa River. (Xinhua/Zhang Rufeng)
A group of bar-headed geese fly over Dragon King Pool park in Lhasa, southwest China's Tibet Autonomous Region, Dec. 25, 2017. The park is home to several species of migratory birds that come here during the winters. (Xinhua/Liu Dongjun)
Photo taken on Dec. 25, 2017 shows the migratory birds flying and swimming at Dragon King Pool park in Lhasa, southwest China's Tibet Autonomous Region. The park is home to several species of migratory birds that come here during the winters. (Xinhua/Liu Dongjun)
Photo taken on Dec. 25, 2017 shows the migratory birds flying and swimming at Dragon King Pool park in Lhasa, southwest China's Tibet Autonomous Region. The park is home to several species of migratory birds that come here during the winters. (Xinhua/Liu Dongjun)
A black-headed gull flies over the water in Dragon King Pool park in Lhasa, southwest China's Tibet Autonomous Region, Dec. 25, 2017. The park is home to several species of migratory birds that come here during the winters. (Xinhua/Liu Dongjun)
Photo taken on Dec. 25, 2017 shows the migratory birds swimming at Dragon King Pool park in Lhasa, southwest China's Tibet Autonomous Region. The park is home to several species of migratory birds that come here during the winters. (Xinhua/Liu Dongjun)
Swans fly over the Swan Lake in Rongcheng national swan nature reserve in Rongcheng City, east China's Shandong Province, Dec. 14, 2017. (Xinhua/Liu Jingshan)
Swans forage on the Swan Lake in Rongcheng national swan nature reserve in Rongcheng City, east China's Shandong Province, Dec. 14, 2017. (Xinhua/Liu Jingshan)
Migratory birds are seen at the Zongjiaolukang Park in Lhasa, capital of southwest China's Tibet Autonomous Region, Dec. 1, 2017. (Xinhua/Purbu Zhaxi)
Migratory birds are seen at the Zongjiaolukang Park in Lhasa, capital of southwest China's Tibet Autonomous Region, Dec. 1, 2017. (Xinhua/Purbu Zhaxi)
Photo taken on Dec. 1, 2017 shows a migratory bird at the Zongjiaolukang Park in Lhasa, capital of southwest China's Tibet Autonomous Region. (Xinhua/Purbu Zhaxi)
Photo taken on Dec. 1, 2017 shows the Potala Palace in Lhasa, capital of southwest China's Tibet Autonomous Region. (Xinhua/Purbu Zhaxi)
White swans are fed at a wetland in Sanmenxia, central China's Henan Province, Dec. 3, 2017. Migratory white swans fly from Siberia to spend the winter time in the wetland. (Xinhua/Zhu Xiang)
White swans are seen at a wetland in Sanmenxia, central China's Henan Province, Dec. 3, 2017. Migratory white swans fly from Siberia to spend the winter time in the wetland. (Xinhua/Zhu Xiang)
White swans are seen at a wetland in Sanmenxia, central China's Henan Province, Dec. 2, 2017. Migratory white swans fly from Siberia to spend the winter time in the wetland. (Xinhua/Zhu Xiang)
White swans are seen at a wetland in Sanmenxia, central China's Henan Province, Dec. 3, 2017. Migratory white swans fly from Siberia to spend the winter time in the wetland. (Xinhua/Zhu Xiang)
White swans are seen at a wetland in Sanmenxia, central China's Henan Province, Dec. 2, 2017. Migratory white swans fly from Siberia to spend the winter time in the wetland. (Xinhua/Zhu Xiang)
White swans are fed at a wetland in Sanmenxia, central China's Henan Province, Dec. 3, 2017. Migratory white swans fly from Siberia to spend the winter time in the wetland. (Xinhua/Zhu Xiang)
Groups of black-necked cranes forage at the Lhasa river valley where they spend the winter season, southwest China's Tibet Autonomous Region, Nov. 23, 2017. Tibet is currently temporary home to over 8,000 black-necked cranes. (Xinhua/Zhang Rufeng)
Groups of black-necked cranes fly over the Lhasa river valley where they spend the winter season, southwest China's Tibet Autonomous Region, Nov. 23, 2017. Tibet is currently temporary home to over 8,000 black-necked cranes. (Xinhua/Zhang Rufeng)
Groups of black-necked cranes forage for food at the Lhasa river valley where they spend the winter season, southwest China's Tibet Autonomous Region, Nov. 23, 2017. Tibet is currently temporary home to over 8,000 black-necked cranes. (Xinhua/Zhang Rufeng)
A flock of oriental white storks are seen at Caofeidian wetland, a vital migratory bird wetland habitat in north China's Hebei Province, Nov. 18, 2017. (Xinhua/Yang Shiyao)
A flock of oriental white storks are seen at Caofeidian wetland, a vital migratory bird wetland habitat in north China's Hebei Province, Nov. 18, 2017. (Xinhua/Yang Shiyao)
A flock of oriental white storks are seen at Caofeidian wetland, a vital migratory bird wetland habitat in north China's Hebei Province, Nov. 18, 2017. (Xinhua/Yang Shiyao)
Migrant birds fly over the Beidagang Wetland in Tianjin, north China, Nov. 15, 2017. Thousands of migrant birds gathered at the wetland for rest. (Xinhua/Yue Yuewei)
Migrant birds fly over the Beidagang Wetland in Tianjin, north China, Nov. 15, 2017. Thousands of migrant birds gathered at the wetland for rest. (Xinhua/Yue Yuewei)
Migrant birds rest at the Beidagang Wetland in Tianjin, north China, Nov. 15, 2017. Thousands of migrant birds gathered at the wetland for rest. (Xinhua/Yue Yuewei)
Migrant birds rest at the Beidagang Wetland in Tianjin, north China, Nov. 15, 2017. Thousands of migrant birds gathered at the wetland for rest. (Xinhua/Yue Yuewei)
Swans are seen on the Guanting Reservoir in Huailai County, north China's Hebei Province, Nov. 14, 2017. (Xinhua/Yang Shiyao)
Swans are seen on the Guanting Reservoir in Huailai County, north China's Hebei Province, Nov. 14, 2017. (Xinhua/Yang Shiyao)
Swans are seen on the Guanting Reservoir in Huailai County, north China's Hebei Province, Nov. 14, 2017. (Xinhua/Yang Shiyao)
