natural landscape image of the wetlands marsh with a great blue heron fishing in black water national wildlife refuge

wetland marsh nature wildlife bird water grass waterbird wilderness river lanscape natural landscape wetlands black national refuge great blue heron fishing nwr waterfowl sanctuary birds migrating critical migration highway atlantic flyway maryland's eastern shore cambridge maryland dorchester freshwater brackish tidal wetlands blackwater united fish • blackwater river tea-colored waters rivers peat marshes species species endangered plants blackwater's marshes winter migration delmarva migrant american animal species management maryland