The United States adopted the bald eagle as its national symbol in 1782, and although once commonly seen across the continent, the species later neared extinction before beginning a dramatic recovery through habitat preservation, regulation of chemical pollutants, increased law enforcement, rehabilitation of injured birds, and captive breeding programs. Eagles have long fished the Missouri River and roosted in tall riverside timber, and because of the importance of this habitat, the U.S. Army Corps of Engineers and the National Wildlife Federation jointly sponsored a 600-acre tract as one of the first U.S. sanctuaries maintained specifically for eagles. In 1970, the National Park Service designated the area as a Registered National Landmark, and a later cooperative project between the National Wildlife Federation and the 7-Eleven Food Stores Division of the Southland Corporation acquired additional private riverbottom habitat used by eagles wintering along the Missouri. In 1974, administration of the area passed to the U.S. Fish and Wildlife Service, and the refuge was named for Karl E. Mundt, a South Dakota senator and supporter of the Endangered Species Act of 1966. Each fall beginning in mid-October, bald eagles gather below Fort Randall Dam along one of the last free-flowing stretches of the Missouri River after being pushed from Canadian nesting grounds by winter, attracted by abundant fish, ducks, geese, ice-free tailwaters, and protected cottonwood roosts. From November to February, immature and mature bald eagles are found near the dam, with peak numbers in December and January, and populations may reach 125 or more, making the area one of the nation's largest wintering concentrations of bald eagles.