Lacreek National Wildlife Refuge in South Dakota encompasses 16,570 acres of protected wetlands, meadows, and planted tree stands managed by the United States Fish and Wildlife Service. Shaped partly by Civilian Conservation Corps work in the 1930s, it uses low dikes and runoff from the nearby Nebraska Sandhills to sustain wetland habitat, especially for migratory birds. Birdlife defines the refuge: since the late 1950s, 281 species have been recorded, with huge seasonal concentrations of ducks and geese, regular wintering trumpeter swans, and occasional endangered whooping cranes and bald eagles. The refuge also supports raptors, mammals, and fish, while allowing limited seasonal hunting and fishing.