Wildlife & Habitat

Mallards using Wetland

Union Slough National Wildlife Refuge is designated as an important migratory waterfowl refuge.

  • Trumpeter Swan

    Trumpeter Swan with Brood

    Trumpeter swans are the largest species of waterfowl in North America. Although once common throughout Iowa, trumpeter swans disappeared from the state in the late 1800’s. The Iowa Department of Natural Resources initiated a trumpeter swan restoration program in the mid 1990’s. Due to this successful program, trumpeter swans are now nesting on the refuge and have become a common sight. Look for them in refuge wetlands from March through November. They are best viewed from the auto tour route and from the county roads that cross the refuge.

  • Bobolink


    Over the past several decades, grassland bird populations have declined more than any other group of North American birds. This decline is due to habitat loss and fragmentation. Union Slough National Wildlife Refuge contains large tracts of prairie, which is essential for grassland birds. The bobolink is one of the many species of grassland birds that can be seen on the Refuge. The male bobolink’s striking spring plumage has the unusual combination of a black underside and a white back. It is the only North American land bird with this color pattern. The bobolink is found on the Refuge from May through early September. It is generally seen in open grassland areas.

  • Muskrat


    The muskrat plays a significant role in the ecology of wetlands at Union Slough National Wildlife Refuge. Muskrats live in the marsh and feed on wetland plants, such as cattails and bulrushes. Muskrats also use these plants to make dome-shaped huts that provide shelter. Muskrat huts are important nesting habitat for some species of water birds. In addition, the feeding and hut building activities of muskrats clears openings in the dense stands of wetland plants. Visitors can see muskrats in refuge wetlands throughout the year.

  • Marsh

    Marsh Habitat

    Union Slough National Wildlife Refuge occurs in the southern part of the Prairie Pothole Region of North America. The Prairie Pothole Region makes up just 10% of North America’s waterfowl breeding habitat, but produces 50% of the continent’s ducks in an average year. The refuge contains about 1300 acres of marsh. It is vitally important to a vast array of water birds for feeding and resting during migration, and is ideal nesting habitat for waterfowl. The robust growth of plants such as cattail, bulrush and pondweed are important to birds and other wildlife for cover and food production. 

  • Tallgrass Prairie

    Tallgrass Prairie

    Tallgrass prairie is a fire-dependent ecosystem characterized by tall grasses, wildflowers, and deep, rich soils. Tallgrass prairie once covered parts of 14 states in the Midwest, including about 80% of Iowa. Less than 0.1% of the original tallgrass prairie in Iowa remains today. Union Slough National Wildlife Refuge contains several good examples of this rare and precious original, or remnant, prairie. The refuge also includes former agricultural fields that are now reconstructed tallgrass prairie. Enjoy the diverse beauty of the tallgrass prairie on both remnant and reconstructed sites as you drive along the auto tour route.