Counties: Kewaunee, Door

Photos:

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Duvall Swamp, Little Mud Lake. Photograph by NHI staff.

Site Description

Duvall Swamp is a privately owned lacustrine swamp located 2 1/2 miles inland from the eastern Green Bay shore, in northwestern Kewaunee County. Much of area was logged in the past, and small areas are continuing to undergo harvest. Grazing has not occurred in the swamp. This extensive second-growth swamp is hardwood dominated, with black ash and white birch the most frequent species. Conifers are present but only as associates. Small patches are dominated by cedar and/or tamarack, with balsam fir, black spruce and white pine also present. The understory is locally brushy with alder, sapling black ash, willow, and dogwood, and the groundlayer indicates that some areas are quite nutrient rich. Populations of three rare plants were documented at this site.

This swamp and a small undeveloped lake embedded within it form the headwaters of the Red River. The lake is surrounded by an open, boggy, quaking sedge mat dominated by waterwillow, sedges, and ericaceous bog shrubs that grades into a zone of shrub-carr and then to cedar swamp. The shrub-carr area is primarily bog birch with dogwood and alder.

As a large block of forest in a predominantly agricultural landscape, this site provides important habitat for a variety of plant and animal species. Initial breeding bird surveys conducted along the site's perimeter indicate that this swamp is an important reserve for species formerly more common within this ecological landscape. Due to it size, location and habitat features this is undoubtedly an important site for migratory songbird stopovers. Additional survey work is needed here, as much of the site was not visited, and some element occurrence records are outdated.

Additional Comments

Though disturbed by extensive logging, this site represents one of the very few large blocks of remnant forest in this heavily developed landscape.