White swans forage at the Ulungur Lake National Wetland Park in Fuhai County, northwest China's Xinjiang Uygur Autonomous Region, Sept. 23, 2020. Located in Fuhai County of Altay, the wetland park is a temporary habitat for migrant birds to fly over the Tianshan Mountains and Altay Mountains. Over the years, the number of migrant birds in the wetland park keeps rising as the local eco-environment improves.Photo:Xinhua

Photo taken on Sept. 23, 2020 shows a flock of birds at the Ulungur Lake National Wetland Park in Fuhai County, northwest China's Xinjiang Uygur Autonomous Region. Located in Fuhai County of Altay, the wetland park is a temporary habitat for migrant birds to fly over the Tianshan Mountains and Altay Mountains. Over the years, the number of migrant birds in the wetland park keeps rising as the local eco-environment improves.Photo:Xinhua

A flock of birds fly over the Ulungur Lake National Wetland Park in Fuhai County, northwest China's Xinjiang Uygur Autonomous Region, Sept. 23, 2020. Located in Fuhai County of Altay, the wetland park is a temporary habitat for migrant birds to fly over the Tianshan Mountains and Altay Mountains. Over the years, the number of migrant birds in the wetland park keeps rising as the local eco-environment improves.Photo:Xinhua

White swans forage at the Ulungur Lake National Wetland Park in Fuhai County, northwest China's Xinjiang Uygur Autonomous Region, Sept. 23, 2020. Located in Fuhai County of Altay, the wetland park is a temporary habitat for migrant birds to fly over the Tianshan Mountains and Altay Mountains. Over the years, the number of migrant birds in the wetland park keeps rising as the local eco-environment improves.Photo:Xinhua