Established in 1929 by President Herbert Hoover, the refuge is physically unimpressive, a small lake in a broad, open, treeless plain. But the 12,383 acres are some of the country's most important nesting grounds for waterfowl, especially mallards, pintail, teal, and canvasback. Bird-watching for waterfowl and prairie species is best early in the morning or in the evening. There's a 9-mile auto-tour route that takes about an hour, marked with signs to provide information about what you're seeing, but Mother Nature is constantly changing the refuge attractions.