Recently, over 20,000 bean geese and mallards were spotted in the Yalu River Estuary Wetland National Nature Reserve in Dandong City, Liaoning Province. During the northward migration period, the wetland can support over 500,000 waterbirds. It is one of the largest stopover sites for migratory wader waterbirds in the world and serves as the most crucial passage and supply station on the bird migration route in Northeast Asia.