Waterfowls forage at a coastal wetland in Beidaihe District of Qinhuangdao, north China's Hebei Province, March 31, 2024. Flocks of migratory birds have made their stopovers in the wetland here recently. (Xinhua/Yang Shiyao)

An aerial drone photo taken on March 31, 2024 shows waterfowls at a coastal wetland in Beidaihe District of Qinhuangdao, north China's Hebei Province. Flocks of migratory birds have made their stopovers in the wetland here recently. (Xinhua/Yang Shiyao)

An aerial drone photo taken on March 31, 2024 shows waterfowls at a coastal wetland in Beidaihe District of Qinhuangdao, north China's Hebei Province. Flocks of migratory birds have made their stopovers in the wetland here recently. (Xinhua/Yang Shiyao)

An aerial drone photo taken on March 31, 2024 shows waterfowls foraging at a coastal wetland in Beidaihe District of Qinhuangdao, north China's Hebei Province. Flocks of migratory birds have made their stopovers in the wetland here recently. (Xinhua/Yang Shiyao)

An aerial drone photo taken on March 31, 2024 shows waterfowls at a coastal wetland in Beidaihe District of Qinhuangdao, north China's Hebei Province. Flocks of migratory birds have made their stopovers in the wetland here recently. (Xinhua/Yang Shiyao)

An aerial drone photo taken on March 31, 2024 shows waterfowls foraging at a coastal wetland in Beidaihe District of Qinhuangdao, north China's Hebei Province. Flocks of migratory birds have made their stopovers in the wetland here recently. (Xinhua/Yang Shiyao)