The Cedarburg Bog is the largest intact wetland complex remaining in southeastern Wisconsin. In addition to its size, the rich botanical diversity of the 2,500-acre Bog with its array of plant communities, many with northern affinities, is unique in its proximity to Wisconsin?s largest center of human population in Milwaukee. The site encompasses conifer swamp, lowland hardwood swamp, shrub-carr, and open marsh. Also unique to this site is the southernmost ?string? bog in North America, a type of patterned peatland typical of boreal regions. Adjacent to the Bog are Cedarburg Beech Woods State Natural Area, one of southeastern Wisconsin?s few remaining examples of intact beech-maple forests, and Sapa Spruce Bog State Natural Area. Both the Cedarburg Bog and Cedarburg Beech Woods are classified as National Natural Landmarks by the U.S. Department of the Interior, and the Bog is part of the national system of Experimental Ecological Reserves designated by the National Science Foundation and Institute of Ecology. Cedarburg Bog harbors populations of various rare, state-endangered and threatened plants, including linear-leaved sundew, dragon?s mouth orchid, ram?s-head lady?s slipper, and prairie white-fringed orchid.
This IBA provides nesting, migratory stopover, and wintering habitat for an extensive list of birds, with nearly 300 species found locally (N.J. Cutright pers. comm. 2006). High conservation priority species breeding here include Acadian Flycatcher, Eastern Wood-Pewee, Willow Flycatcher, Veery, Wood Thrush, Marsh Wren, Nashville Warbler, Black-and-white Warbler, Ovenbird, and Rose-breasted Grosbeak. Northern plant communities support small numbers of a variety of northern bird species that breed here at the extreme southern limit of their geographic range (Idzikowski 1982), among them Brown Creeper, Canada Warbler, Northern Waterthrush, and White-throated Sparrow. This site is the extreme southeasternmost breeding location in Wisconsin for Golden-crowed Kinglet (Merkel 2006). Cedarburg Bog is an important migratory stopover habitat, with over 100 species captured during a long-term autumn banding program that extended over a thirty-year period (though 1996). Thousands of migrants utilize the Bog and Beech Woods during both migratory periods (Weise 1988). This site also is significant for long-term research, education, and monitoring. Cedarburg Bog and Beech Woods have been the home of the University of Wisconsin-Milwaukee Field Station since the late 1960s. A long history of field research has resulted in over 230 publications and 127 Ph.D. dissertations and Masters? theses, many related to birds. The late Professor Charles M. Weise and Professors Millicent Ficken, Peter Dunn, and Linda Whittingham have conducted long-term research projects here (Weise et al. 2004), and both graduate and undergraduate students working with them have contributed to this rich research history. The Field Station is engaged in long-term monitoring of changes in breeding and migrant birds in the Bog and Beech Woods, with recent ornithological investigations utilizing the Field Station?s long-term datasets on weather and vegetation.
The Cedarburg Bog IBA with its three state natural areas is jointly managed and protected by the University of Wisconsin-Milwaukee and the Wisconsin Department of Natural Resources. Threats within and adjacent to this area include the invasion of exotic plants (particularly glossy buckthorn), agricultural runoff, and development on surrounding private lands.