U.S. Fish & Wildlife Service logo A Unit of the National Wildlife Refuge System
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Gravel Island
National Wildlife Refuge

double-crested cormorant standing on rock

Door County, WI   
E-mail: gravelisland@fws.gov
Phone Number: 920-387-2658
Visit the Refuge's Web Site:
Double-crested cormorants nest on both Gravel and Spider islands.
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  Wildlife and Habitat

Continued . . .

Spider Island had a birch-cedar-tamarack forest until the 1970s, but it has since succumbed to the activities of thousands of colonially nesting birds that breed there. All of the trees have now fallen over or been washed away. Waterfowl use is limited since there is very sparse vegetation, but the fallen trees of Spider Island do provide some cover for scattered nesting of species like mallards, black ducks, and Canada geese. Gravel Island has no permanent vegetation due to periodic overwashing by waves and ice during high water years.

Together, Gravel and Spider islands support large colonies of herring gulls and double-crested cormorants. A caspian tern colony and one pair of black-backed gulls have nested on Gravel Island during the last several years. The shores of Gravel and Spider provide shorebird habitat during low-water conditions. In such circumstances, a wide, flat area of dolomite pavement becomes exposed and numerous fissures and shallow depressions in limestone retain water after rain, storms, or heavy seas. This water is quickly warmed and, along with racks of vegetation that wash up, supports invertebates and feeding shorebirds.

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