Aerial photo taken on May 28, 2020, shows Lalu wetland in Lhasa, southwest China's Tibet Autonomous Region. Lalu wetland national nature reserve, with an altitude of about 3,600 meters, covers an area of nearly 13 square kilometers. Over 5,000 birds of more than 20 species inhabit here throughout the year. In winter, dozens of species of migratory birds flew to the wetland. (Photo: China News Service/He Penglei)

Aerial photo taken on May 28, 2020, shows Lalu wetland in Lhasa, southwest China's Tibet Autonomous Region. Lalu wetland national nature reserve, with an altitude of about 3,600 meters, covers an area of nearly 13 square kilometers. Over 5,000 birds of more than 20 species inhabit here throughout the year. In winter, dozens of species of migratory birds flew to the wetland. (Photo: China News Service/He Penglei)

Aerial photo taken on May 28, 2020, shows Lalu wetland in Lhasa, southwest China's Tibet Autonomous Region. Lalu wetland national nature reserve, with an altitude of about 3,600 meters, covers an area of nearly 13 square kilometers. Over 5,000 birds of more than 20 species inhabit here throughout the year. In winter, dozens of species of migratory birds flew to the wetland. (Photo: China News Service/He Penglei)

Aerial photo taken on May 28, 2020, shows Lalu wetland in Lhasa, southwest China's Tibet Autonomous Region. Lalu wetland national nature reserve, with an altitude of about 3,600 meters, covers an area of nearly 13 square kilometers. Over 5,000 birds of more than 20 species inhabit here throughout the year. In winter, dozens of species of migratory birds flew to the wetland. (Photo: China News Service/He Penglei)