Natural Monument No. 179 - Migratory Birds Sanctuary of the Nakdonggang River Estuary The habitat is one of the largest migratory birds sanctuaries in Korea. It has many big and small dunes shaped by the river's flow and tide. Thanks to its location at the ecotone between sea- and fresh-water, there are abundant foods for birds such as plankton, shellfish, and small fish. It can be the top sanctuary for migratory birds.