Guide to Significant Wildlife Habitat - Door County Web Map

Detroit Island
Detroit Island is 2.3 miles long by .08-0.4 miles wide, is located a few hundreds yards east of the
Washington Island ferry dock, and ranges up to 25 meters above Lake Michigan. The island is primarily
privately owned. Despite large deer populations, the island has high ecological quality and should be
considered by the DNR for State Natural Area designation (Judziewicz and Kopitzke 1999).
• Detroit Island is in the Town of Washington. Washington has adopted the county’s zoning ordinance.
• Land use is predominantly natural area and estate along the shoreline of the north half of the island.
• Silurian dolostone outcrops, and interior low escarpments underlay the surface of the island. The
shore at the southern tip is considered a high quality Great Lakes alkaline rock shore community
(Judziewicz and Kopitzke 1999). Soils are of Summerville-Longrie-Omena association (USDA SCS
1978).
• Vegetation includes recent, select-cut forests of sugar maple, white birch, red maple, basswood, red
oak, and hop-hornbeam (Ostrya virginiana). In interior portions of the island are occasional balsam
fir and beech trees. Because of the recent cutting, species such as red raspberry, chokecherry, and
common hound’s tongue are common.
• Common species in low dolostone scarps include marginal shield fern (Dryopteris marginalis) and
yellow lady’s slipper (Cypripedium pubenscens). Large canopy white pines are found along the west
coast of the island. Ephemeral plants such as Dutchman’s-breeches (Dicentra cucullaria), big white
trilliums (Trillium grandiflorum.), wild leeks (Allium tricoccum), and Canada and yellow violets
(Viola canadensis and V. pubescens) are found on the central hill. On the northwest portion of the
island is a small black ash swamp with tag alder (Alnus incana) and lake sedge (Carex lacustris).
• A Great Lakes alkaline rockshore forms the southern tip of Detroit Island. This special community of
plants includes Baltic rush (Juncus arcticus subsp. littoralis), silverweed (Argentina anserina), bird’seye
primrose (Primula mistassinica), low calamint, white camass, Indian paintbrush (Castilleja
coccinea), and Seneca snakeroot. There are various sedges (Carex aurea, C. crawei, C. viridula, and
Rhynchospora capillacea), marsh fern (Thelypteris palustris), tufted hairgrass, alvar violet, brook
lobelia, frost aster (Aster pilosus), shrubby St. John’s-wort (Hypericum kalmianum), and lesser
fringed gentian. Most of the coast surrounding the island contains white cedar. Sandy swales
support several colonies of dwarf lake iris (Judziewicz and Kopitzke 1999).
• Animal life includes high populations of white-tailed deer and shore birds during migration
(Judziewicz and Kopitzke 1999). A diverse assemblage of reptiles includes northern-banded water
snakes. Rare plant species occur along the south tip of the island within the alkaline rockshore
community (Judziewicz and Kopitzke 1999).
Rock Island
Rock Island is approximately 900 acres and is the highest island in the Grand Traverse
archipelago reaching 65 meters above Lake Michigan. Considered the gem of all islands in the chain, it is
the most remote from the mainland of Door County. Rock Island was named a Wisconsin State Park in
1964 and later 570 acres was designated as a State Natural Area in 2002. Rock Island is owned and
managed by the Wisconsin Department of Natural Resources. Threats to Rock Island include deer
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Grand Traverse Islands