Swan Lake Important Bird Area is located in Nicollet County Minnesota, approximately 90 miles southwest of Minneapolis. State Highway 111 bisects the area, US Highway 14 runs along a portion of the IBAs southern border and County Route 5 is on the northern boundary. Swan Lake IBA includes the 10,000 acre Swan Lake, as well as three smaller lakes, Mud Lake, Middle Lake and Little Lake. Swan Lake is the largest prairie pothole type wetland in the US, and is designated as a wildlife lake by the Minnesota Department of Natural Resources. This designation allows managers to temporarily lower water levels to enhance vegetation and control invasive fish species. Twenty-six subunits of the Swan Lake Wildlife Management Area are included within the boundaries of this IBA. Swan Lake IBA is one of the few locations in south central Minnesota where a large, intact wetland system complete with diverse native wetland and upland plant communities, and the bird and wildlife populations they support, can be observed.
The Upper Minnesota River valley IBA is located just to the south of Swan Lake and is known for its function as a migratory corridor to a wide diversity of birds. Swan Lake is a stand out in the area, otherwise dominated by agriculture, for the number and diversity of waterbirds and waterfowl that use the area. This is an area in south central Minnesota where serious habitat degradation has not occurred so aquatic plants and shoreline sedges and grasses that are difficult to find in other areas still exist here.
According to the Minnesota Department of Natural Resources, the Natural Heritage database identifies three native plant communities of ecological significance within the Swan lake IBA:
Bulrush (prairie) marsh, Sugar Maple Forest (Big Woods) and Elm- Basswood- Black Ash (Hackberry).
According to an article on the Swan Lake Restoration Project (Mahmoodi, 2001) Swan Lake was historically used by various indigenous peoples including the Mississippian farming-oriented culture and the Dakota/Sisseton Indians, all attracted to the lake for its abundance of wildlife. In the late 1800?s settlers began farming the land more intensively. The practice of clearing the trees and diverting water in order to expand areas of agricultural land continued well into the mid 1950?s. In 1973 the MN DNR was granted authority to manage Swan Lake by designating it as a Wildlife Lake.
Swan Lake is a great birding spot year-round. In the summer there is a large breeding colony of Red-necked, Eared and Western Grebes. The lake is also home to a large Black-crowned Night Heron rookery and hosts a breeding population of Least Bitterns as well as Forster?s and Black Terns. Swamp Sparrows and Marsh Wrens are also common here. In spring, just about all the waterfowl usually found in southwestern MN occurs here including a few rare occasional visitors.
Aside from the lakes, the area is interspersed with grasslands, marshes and swamps. Grassland species are well represented in this IBA including the Henslow?s Sparrow in publicly managed areas that have not been burned within the past 3-4 years. In winter, a variety of hawks and the occasional Snowy Owl can be seen in the area.
MN1c - Significant concentrations of breeding, migrating or wintering waterbirds:
The Minnesota DNR conducted a colonial waterbird survey on Swan Lake in 2000 and 2001 documenting numbers meeting or exceeding these criteria. Forster?s Tern breeding data exceeds the minimum numbers with 182 individuals observed in July of 2000 and 102 in 2001. Likewise with Black Terns with 362 adults and 205 juveniles observed in 2001. Four species of grebe; Red-necked, Western, Eared and Pied-billed, are documented as regularly breeding at the lake with numbers collectively exceeding 100 breeding pairs.
MN1e ? Species Diversity
Approximately 191 species have been documented within the Swan Lake IBA (Appendix 1). Including 24 species of shorebirds:
MN2a - Endangered, threatened or species of special concern.
Three State listed species have been documented within the Swan Lake IBA. Forster?s Terns (special concern) and Trumpeter Swans (threatened) have been documented nesting here and the American White Pelican (special concern) has been observed within the IBA in high numbers but no nesting has been documented. Henslow?s Sparrows (endangered) have also been observed within the surrounding grasslands of the Swan lake IBA (appendix 1), yet there is no quantitative information available.
MN2b- Species of conservation concern
Three species of conservation concern; the Black-crowned Night Heron, Black Tern and Least Bittern all nest in or around Swan Lake.
MN-3. Rare, threatened, or unique habitat assemblages.
The site contains an assemblage of species representative of the Sedge Wetland habitat type, with 8 of the 9 criteria species observed:
Le Conte's Sparrow
The expansion of agriculture is a continuing threat in this area. Tiling and ditching leads to inputs of water which can contribute to increased water erosion, agricultural runoff (nutrients, chemicals), and invasive species (plant & animal).
An additional threat is introduced carp that have significant impacts on water quality and native plant communities. In the past, DNR Wildlife has conducted fall/winter drawdowns and applied rotenone to the lake to address the carp problem and to help reestablish native plants. That poses a short-term impact to birds such as waterbirds, eagles, etc. but in the long-term should benefit them. They also have adjacent & nearby alternatives such as Middle Lake & Duck Lake.