A parent hoopoe feeds its nestling in Qiqihar City, northeast China's Heilongjiang Province, June 14, 2026. Wetlands and nature reserves in Heilongjiang Province have entered the critical period for the breeding of northbound migratory birds, since the beginning of summer. (Photo by Wang Yonggang/Xinhua)

A parent bearded reedling feeds its nestlings at the Keqin Lake wetland area in Qiqihar City, northeast China's Heilongjiang Province, June 25, 2026. Wetlands and nature reserves in Heilongjiang Province have entered the critical period for the breeding of northbound migratory birds, since the beginning of summer. (Photo by Wang Yonggang/Xinhua)

A drone photo taken on June 19, 2026 shows the white-naped cranes foraging with their nestlings at the Sanhuanpao National Nature Reserve in northeast China's Heilongjiang Province. Wetlands and nature reserves in Heilongjiang Province have entered the critical period for the breeding of northbound migratory birds, since the beginning of summer. (Photo by Qu Yubao/Xinhua)

A drone photo taken on June 25, 2026 shows a parent oriental white stork taking care of its nestlings in its nest in Jiagedaqi, Greater Khingan Mountains, northeast China's Heilongjiang Province. Wetlands and nature reserves in Heilongjiang Province have entered the critical period for the breeding of northbound migratory birds, since the beginning of summer. (Photo by Zhuang Yu/Xinhua)

A drone photo taken on June 24, 2026 shows the crested grebes foraging with their nestlings at the Fujin National Wetland Park in Fujin City, northeast China's Heilongjiang Province. Wetlands and nature reserves in Heilongjiang Province have entered the critical period for the breeding of northbound migratory birds, since the beginning of summer. (Photo by Qu Yubao/Xinhua)

A drone photo taken on June 23, 2026 shows a parent egret taking care of its nestlings at the Anbang River National Wetland Park in Shuangyashan City, northeast China's Heilongjiang Province. Wetlands and nature reserves in Heilongjiang Province have entered the critical period for the breeding of northbound migratory birds, since the beginning of summer. (Photo by Han Yang/Xinhua)

A drone photo taken on June 25, 2026 shows the parent egrets raising their nestlings in their nests at a wetland near Qingshan Lake in Hulin City, northeast China's Heilongjiang Province. Wetlands and nature reserves in Heilongjiang Province have entered the critical period for the breeding of northbound migratory birds, since the beginning of summer. (Photo by Huang Yongxing/Xinhua)

The mandarin duck nestlings comb their feathers following their parent on the shore of a water area at Sun Island Scenic Area in Harbin, northeast China's Heilongjiang Province, June 22, 2026. Wetlands and nature reserves in Heilongjiang Province have entered the critical period for the breeding of northbound migratory birds, since the beginning of summer. (Photo by Zhang Shu/Xinhua)

A drone photo taken on June 23, 2026 shows the parent white spoonbills guarding their nestlings at a migratory bird habitat in Tongjiang City, northeast China's Heilongjiang Province. Wetlands and nature reserves in Heilongjiang Province have entered the critical period for the breeding of northbound migratory birds, since the beginning of summer. (Photo by Liu Wanping/Xinhua)

A drone photo taken on June 24, 2026 shows a parent mallard foraging with its nestlings beside Ganhe River in Jiagedaqi, Greater Khingan Mountains, northeast China's Heilongjiang Province. Wetlands and nature reserves in Heilongjiang Province have entered the critical period for the breeding of northbound migratory birds, since the beginning of summer. (Photo by Zhuang Yu/Xinhua)

A drone photo taken on June 19, 2026 shows an oriental white stork feeding its nestlings in their nest at the Sanhuanpao National Nature Reserve in northeast China's Heilongjiang Province. Wetlands and nature reserves in Heilongjiang Province have entered the critical period for the breeding of northbound migratory birds, since the beginning of summer. (Photo by Qu Yubao/Xinhua)