Migrant birds fly over Ulan Suhai Lake in Bayan Nur, north China's Inner Mongolia Autonomous Region, Oct. 28, 2020. The wetland of Ulan Suhai Lake is an important breeding location for migrant birds.Photo:Xinhua

Migrant birds are seen at Ulan Suhai Lake in Bayan Nur, north China's Inner Mongolia Autonomous Region, Oct. 27, 2020. The wetland of Ulan Suhai Lake is an important breeding location for migrant birds.Photo:Xinhua

Aerial photo taken on Oct. 28, 2020 shows Ulan Suhai Lake in Bayan Nur, north China's Inner Mongolia Autonomous Region. The wetland of Ulan Suhai Lake is an important breeding location for migrant birds.Photo:Xinhua

Migrant birds fly over Ulan Suhai Lake in Bayan Nur, north China's Inner Mongolia Autonomous Region, Oct. 28, 2020. The wetland of Ulan Suhai Lake is an important breeding location for migrant birds.Photo:Xinhua

Migrant birds are seen at Ulan Suhai Lake in Bayan Nur, north China's Inner Mongolia Autonomous Region, Oct. 28, 2020. The wetland of Ulan Suhai Lake is an important breeding location for migrant birds.Photo:Xinhua

Migrant birds fly over Ulan Suhai Lake in Bayan Nur, north China's Inner Mongolia Autonomous Region, Oct. 28, 2020. The wetland of Ulan Suhai Lake is an important breeding location for migrant birds.Photo:Xinhua

Migrant birds fly over Ulan Suhai Lake in Bayan Nur, north China's Inner Mongolia Autonomous Region, Oct. 27, 2020. The wetland of Ulan Suhai Lake is an important breeding location for migrant birds.Photo:Xinhua