This IBA encompasses most of the geological feature called the Blue Hills. The rugged topography was formed millions of years ago and has since weathered and eroded to its present configuration. The underlying quartzite is very resistant, with four glacial events failing to pulverize it. The last event, the great Wisconsinan glacier, stalled at the edge of the hills and exhibited great freezing and thawing fluctuations. These extremes helped form unusual geological features, such as felsenmeers and hanging valleys. Numerous streams flow over the bedrock and cobble. The glacier dug depressions that are now scattered lakes and bogs. The bedrock-influenced landscape is mostly vegetated with forests of oaks, aspen and maples. Small patches of hemlock, white cedar, white pine, and yellow birch occur in the uplands, and bogs have the typical conifer species (tamarack, black spruce, white cedar, etc.). Past agricultural and tourist ventures are mostly gone, with most of the land now in county forest. Some agriculture still is present and the Blue Hills remain a popular recreation destination. Primary vegetative cover types include bottomland hardwoods, lowland brush, young deciduous upland forest, mature deciduous upland forest, mixed hardwood-conifer forest, mature conifer, oak forest, cool season grasslands, and scattered planted conifers and bog. The unique geologic features support populations of very rare plants.
This site contains an extensive forested tract that supports populations of various high-priority species. It is considered a core habitat for Cerulean Warbler, with up to 30,000 acres of suitable habitat available for this species. Other species of large forested landscapes that breed here include Least Flycatcher, Yellow-throated Vireo, Wood Thrush, Black-throated Blue Warbler, and Black-throated Green Warbler. The bog relicts hold species such as Northern Waterthrush, Nashville Warbler, Pine Warbler, and Lincoln?s Sparrow nearly every year. Grassland areas support small numbers of Henslow?s Sparrow, Savannah Sparrow, Bobolink, Eastern Meadowlark, and Western Meadowlark.
This area largely is county forest land, managed for forest production and recreation. The extensive forested landscape is the most significant feature of this IBA, and holds high conservation significance (Pohlman et al. 2006). Maintaining large tracts of forest intact and unfragmented is critical to populations of forest-dwelling birds, a number of which are area-sensitive. Several species, including Cerulean Warbler and Black-throated Blue Warbler, additionally require mature, structurally complex stands (WDNR 2005). Active forest management already has created suitable habitat in some areas. Modification of select harvest regimes potentially could be developed into the largest Cerulean Warbler management area in the state. Actual or potential threats to this area include fragmentation, unsustainable forest management practices, recreational disturbance or overuse, development, deer over-browsing, and invasive species.