Each spring and fall for thousands of years, the Mississippi River corridor has served as an important migration route for millions of birds. Waterfowl provide spectacular seasonal flights with thousands of mallards, pintail, wigeon, blue-winged and green winged teal, scaup, shoveler, gadwall, canvasback and geese commonly seen. Refuge wetlands also provide important mudflat and shallow water habitat where herons, egrets, and shorebirds can feed and rest. Marshy areas provide habitat for species such as rails and bitterns. The best places to see waterfowl are from the refuge overlooks on the Louisa Division.