The Baraboo Range is the remains of a Precambrian rock formation known as Baraboo Quartzite, one of the most ancient rock outcroppings in North America. Topography is steep with bedrock close to the surface in many areas. This area contains the largest block of southern forest in Wisconsin and one of the largest in the Midwest. The southern slopes are forested with oaks and hickory; north-facing slopes are mostly maple, basswood, and oak. Scattered ravines and steep valleys harbor northern species such as white pine, hemlock, and yellow birch. Other habitats present include oak savanna, native prairie, cool season grasses, and cliffs and talus slopes. The Baraboo Hills are ecologically very diverse and contain a variety of natural communities and many rare species of plants and animals.
The Baraboo Hills supports a diverse breeding avifauna of some 135 species, including numerous high-priority species such as Red-headed Woodpecker, Acadian Flycatcher, Hooded Warbler and Worm-eating Warbler. Large, intact forested blocks, characteristic of the site, are especially valuable for forest-interior birds. The site is considered a Cerulean Warbler core habitat, with up to 30,000 acres of suitable habitat available for this species. It is one of the few sites in the state where Yellow-throated Warblers are thought to breed. Hemlock and pine relicts host small populations of species more typical of northern forests, such as Blackburnian Warbler, Black-throated Green Warbler, Northern Parula, Canada Warbler, Magnolia Warbler and Winter Wren. Smaller pockets of grassland, shrubland and marsh provide habitat for high-priority species such as Sedge Wren, Swamp Sparrow, Field Sparrow, Henslow's Sparrow and Bobolink. The area is a concentration area for migratory landbirds in both spring and fall, supporting greater than 10,000 migrants per season. Greater than 25% of the state?s Turkey Vultures congregate here in the fall. The Baraboo Hills contain more rare species and diverse concentrations than any other similar sized forested area in southern Wisconsin and are considered critical for bird conservation. The area continues to be an important avian research and monitoring site, especially regarding the habitat needs of forest area-sensitive species, and is the site of many educational field trips and workshops annually.
The Baraboo Hills have long been recognized as ecologically unique and valuable. There are numerous preserves, State Natural Areas, and two state parks. The southern range of the Baraboo Hills was designated a National Natural Landmark by the National Park Service in 1980. The Nature Conservancy has named the Baraboo Hills a Last Great Place, one of only 200 such sites worldwide. Some 30,000 acres in the Baraboo Hills have been targeted for conservation through the Forest Legacy Program. Various organizations, including The Nature Conservancy, the Wisconsin Society for Ornithology, the University of Wisconsin, the Baraboo Range Preservation Association and the Wisconsin Department of Natural Resources have formed a strong conservation partnership and protected thousands of acres through acquisitions, easements, and voluntary agreements. The Baraboo Hills represent one of the best opportunities in Wisconsin and in the whole upper Midwest to manage for southern forest interior birds. Forested habitats are experiencing a variety of threats. The expansion of U.S. Highway 12 between Baraboo and Madison has increased development pressures as commuting becomes more feasible. Quicker and easier access to the Baraboo Hills, already a popular tourist destination, may lead to recreational overuse and degradation of fragile areas. Invasive species such as garlic mustard and buckthorn, lack of oak regeneration, over-browsing by deer, and unsustainable timber management, particularly on private lands, also are threats. Maintaining and improving large, intact blocks of forest should continue to be a focus of conservation efforts. Outreach efforts to private landowners to encourage sustainable forest management practices should be continued and expanded. Bird monitoring efforts should be maintained and expanded to sites where monitoring gaps exist or where active management is planned.