Hidden in the cornfields of north-central Iowa is a winding, shallow valley, its floor a chain of lakes, ponds and wetlands. While not readily visible from the surrounding landscape, this watery oasis is surely eye-catching for migrant waterfowl and, since 1937, Union Slough has been protected as a National Wildlife Refuge.
The preserve is best reached by taking Exit 119 from I-90 (at Blue Earth, MN) and heading south on US 169 for almost 35 miles; turn left (east) on A-42 and proceed another 5 miles to the refuge office. An access road is closed throughout the breeding season but the various habitats of Union Slough can be viewed from other county roads in the area (a map is available at the office).
A wide variety of waterfowl, grebes, shorebirds and American white pelicans stop here during migrations and many other species inhabit the valley. Nesting birds of note include trumpeter swans, double-crested cormorants, American and least bitterns, black-crowned night herons, hooded mergansers, Cooper's hawks, gray partridges, ring-necked pheasants, king and Virginia rails, common snipe, Wilson's phalaropes, long-eared owls, willow flycatchers, sedge wrens and savannah sparrows. A large muskrat colony occupies a marsh near the north end of the Slough.
