The proposed IBA lies along the St. Croix River within the Anoka Sand Plain and Mille Lacs Uplands subsections, a region on the southern edge of the transition zone of pine forest, hardwood forest, and oak savanna. It encompasses a wide variety of habitats, including oak savanna, floodplain forest, maple-basswood forest, oak forest, two types of hardwood forest and, at its northernmost edge, conifer swamp forest. In short, this IBA transitions through three major forest types that divide into at least seven distinct habitats in only 24 miles of river.
From roughly County Road 16 south, the land drops steeply toward the St. Croix. Upland areas contain oak forest, but lowland hardwood forests predominate here, interrupted by scattered maple-basswood forest patches. The hills, bisected by ravines, are covered with black and green ash, aspen, bur oak, maples, slippery elm, and aspen. Northern pin and red oak trees are common at scattered locations within these forests, as are white and red pine trees. The dirt here is richer and loamier than it is farther north and the hills, though covered with soil, are higher and steeper.
The proposed Important Birding Area has three prominent features: the St. Croix River, the area?s exceptional biodiversity, and the convergence of two major life zones ? the Carolinian, from the south, and the Boreal, from the north. These three features combine to produce exceptional bird habitat, as reflected by the over 200 species of birds recorded within this IBA,
The St. Croix River, a federally protected National Scenic Riverway, is often identified as one of the Upper Midwest?s most pristine large river ecosystems. In just 164 miles, it crosses three forest types and two major life zones, which meet in the proposed Important Birding Area located within Wild River State Park. The river and its environs provide important nesting habitat and a migratory flyway for a wide variety of birds.
The MN County Biological Survey has classified slightly over half the habitat within Wild River State Park, which comprises most of the IBA, as being of "Outstanding" biodiversity significance. Roughly ¾ mile north of the hydroelectrical dam, another area of exceptional diversity runs north for 2 ¾ miles. The Minnesota DNR identifies the area as rich in key habitats for supporting Species in Greatest Conservation Need (SGCN). The greatest number of species and habitat occur directly along the St. Croix River, within the proposed IBA.
In addition to the proposed IBA?s spectacular river and outstanding biodiversity, it is located south of Crex Meadows, a natural ?duck factory? home to roughly 270 species of birds, and has at least two stretches of river that are open throughout most of the winter. This combination of diverse habitat, location, and open water makes the proposed IBA an important stopover point for migrating and over-wintering birds, including swans, geese, ducks, eagles, warblers, vireos, thrushes, flycatchers, and sparrows.
Cell towers, wind towers, and power lines are proposed along the bluffs overlooking the St. Croix River nearly each year. Xcel Energy and Dairyland power are continuing to push for construction of a large power line at or just below the proposed IBA?s southernmost border.
Deforestation is linked to housing developments; however, most of the area within the IBA is protected by Wild River State Park. The area immediately outside the park faces intense development pressure, although areas adjacent to the St. Croix River are protected by a combination of County and Federal regulation.
Disturbance to birds is associated with recreational use of the river; however, the upper St. Croix sees much less intense recreational use than the lower St. Croix.
Urbanization. Although the area within Wild River Park is protected, land outside the park and immediately adjacent to the IBA faces intense development pressure. Issues include surface and groundwater contamination, habitat loss, and feral animals. A 1996 study of mussels in the Sunrise River (an impaired river that feeds into the Saint Croix within the bounds of the proposed IBA) linked intensive agricultural and urban land use to degraded water quality. It is worth noting that the Sunrise has a feedlot on its banks; however, given the urbanization occurring in the area, it appears that intensive urbanization will present more of a challenge than will agricultural expansion.
Introduced animals and feral pets. Anecdotal evidence from area newspapers suggests that feral dogs and cats are an increasing problem.