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Union Slough
National Wildlife Refuge

male bobolink
1710 360th St.
Titonka, IA   50480
E-mail: unionslough@fws.gov
Phone Number: 515-928-2523
Visit the Refuge's Web Site:
Grassland songbirds such as bobolinks find habitat in Union Slough Refuge's tallgrass prairie.
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Original surveyors' notes of Kossuth County, Iowa, described the northern portion of the refuge as containing "many swamps and marshes, ponds and sloughs." The area is further described as gently rolling with "no timber and containing good, dry tillable land generally good for grass." The surveyors described the southern portion of the refuge as a gently rolling prairie with numerous small marshes and many of considerable extent.

Maps, surveyors' notes, and the Soil Survey of Kossuth County Iowa described a single area, about 20 acres in size, that contained woody vegetation. Other than that one area, historical conditions of Union Slough National Wildlife Refuge were primarily tallgrass prairie.

Recurrent wildfires and grazing, mostly by bison, kept woody species at bay, allowing grasses and forbs to thrive. Prairie chickens, whooping cranes, numerous species of grassland birds, and a variety of waterfowl were common to the area. As settlers moved west and discovered the rich, organic soils, however, the conversion of grassland to cropland began.

For nearly 50 years following the initial alteration of the native prairie, populations of many grassland-dependent wildlife remained relatively stable by using haylands and pastures. However, since 1950, the acreage of agricultural grasslands has significantly declined.

When the refuge was established in 1938, numerous grasslands flanked the boundary. Today, there are very few, if any, and the land surrounding Union Slough Refuge is intensively farmed. The alteration of habitat reflects the evolution of agriculture, coupled with the loss of grazing and fire. The refuge remains an island of critical nesting habitat for waterfowl and other migratory birds.

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