Green Bay National Wildlife Refuge

Fish and Wildlife Service, Wisconsin.

On February 21, 1912, President William Howard Taft established Green Bay National Wildlife Refuge, our nation’s 28th refuge and only the second refuge in the Great Lakes region. Located in Lake Michigan, off the tip of Wisconsin’s Door Peninsula, the refuge started as a mere 2-acre island that was originally named Green Bay Reservation. Today, this essential stopover habitat for birds and other migratory species consists of five islands and is framed by Wisconsin and Michigan.  

The refuge is now made up of the following six units:  

These islands act collectively as stepping stones for migrating birds, bats and butterflies as they cross along this section of the Niagara Escarpment – an outcropping of limestone that stretches in a wide arc from eastern Wisconsin through Michigan’s Upper Peninsula, across Ontario, Canada and on through the Niagara Falls in New York.

Long before European settlement in Wisconsin, several different Native American Tribes occupied and traversed where were historically called “the Potowatomi Islands.” Located in what is now northern Door County, Wisconsin and southern Delta County, Michigan, this archipelago enabled otherwise distant Tribes an opportunity for safer travel and trade among Lake Michigan’s treacherous waters.

The chain of islands sprinkled between peninsulas are valuable patches of habitat for a variety of migratory species during both the migration and the breeding season. Hog, Pilot and Rocky islands are valuable as colonial waterbird breeding, nesting and loafing sites. The location of these islands near forage fish habitat, combined with their remote and undisturbed condition, offer these species of migratory birds the necessary protected habitat. Habitat for colonial waterbirds has been under intense pressure on some Great Lakes islands as shoreline development continues.

Larger, forested islands also provide valuable feeding and resting stops for songbirds, bats and monarch butterflies migrating across open water. Habitat types differ from dense northern mesic forest, early successional forest and shrubby understory, to open habitat types of grassland, wetland and shoreline areas. Shoreline habitats on the islands range from sandy and silty areas to areas of exposed limestone bedrock, loose cobble-stone alkaline shoreline and globally rare alvar habitat containing specialized plants species.

Biologists and land managers have been roughing the waves and extreme weather of Lake Michigan to help colonial nesting waterbirds birds for more than 100 years, but the refuge boasts more than nesting birds. While they started with a small footprint that focused on bird conservation, botanists and other researchers from around the world have come to study the diverse plant life that has persisted here for millennia.

The Green Bay National Wildlife Refuge is managed by staff at the Horicon National Wildlife Refuge Complex in Mayville, Wisconsin.

Hog Island was set aside by Executive Order 1487 in 1912 as a preserve and breeding ground for native birds, making it one of the oldest national wildlife refuges in the nation! As many bird species were being extirpated due to the plume trade and market hunting of the era, Hog Island was home to some of the only remaining nesting habitat for herons and egrets. Today that habitat continues to be preserved, and herons and egrets continue to return to the island year after year to raise young.

In 1970, the United States Congress designated Hog island as part of the Wisconsin Islands Wilderness Area. Along with nearby islands of Gravel Island National Wildlife Refuge this wilderness area is one of the smallest wilderness areas in the country, at 29 acres. The prime management consideration of the wilderness status was the continued protection of nesting birds by limiting access to the islands during the breeding seasons. For this reason, these wilderness islands are closed to public visitation. The wilderness designation provides an additional level of protection on the islands and boaters are asked to stay at least a quarter mile offshore so as not to endanger the nesting areas.

Plum and Pilot islands were added to the refuge on October 17, 2007. Jurisdiction of the islands was transferred from the U.S. Coast Guard to the U.S. Fish and Wildlife Service through Public Land Order 7681 to become part of Green Bay National Wildlife Refuge, with a purpose to protect native and migratory bird habitat and endangered species habitat within the Great Lakes Basin ecosystem. The islands were excess to the Coast Guard’s needs and therefore made available to other federal agencies.

Today, Plum and Pilot islands continue to conserve and protect the vital habitats for fish, plants, and wildlife. The islands have also played a significant role in the maritime history of Wisconsin and are home to buildings found on the National Register of Historic Places. Green Bay National Wildlife Refuge works in partnership with the Friends of Plum and Pilot Island to meet historic preservation goals for these structures, and to continue tell the stories of the sites.

Plum Island is open for public access Memorial Day through Labor Day during daylight hours only. Pilot Island remains closed to public access to meet the primary conservation purpose of the site for migratory and colonial nesting birds, and as related to the State of Wisconsin’s terms for the 2007 lands transfer.

Rocky Island, located near the Garden Peninsula of the upper peninsula of Michigan, was added to the refuge on August 14,2014. This 10-acre island was donated to The Nature Conservancy in 1986, and transferred to the U.S. Fish and Wildlife Service to protect native and migratory bird and endangered species habitat within the Great Lakes Basin ecosystem. 

Rocky Island is located approximately two miles off Michigan’s Garden Peninsula in close proximity to Little Summer Island.

Rocky Island is closed to all public use to protect those species and their habitat.

St. Martin Island was added to the refuge on September 21, 2015. This large, forested island protects native and migratory bird habitats, as well as vital endangered species habitat for plants such as the Canada yew and dwarf lake iris. Other species of concern found on the island include American sea rocket, dune goldenrod, white camas and climbing fumitory.

St. Martin Island is part of the Niagara Escarpment and has significant bluffs, which have rare native snails and plants associated with them. In addition to the bluffs, the island also supports forests, wetlands and an extensive cobblestone beach.

The Nature Conservancy purchased the majority of St. Martin Island - 1,244 acres - from the Fred Luber family in 2013, and an additional 36 acres from David Uihlein, Jr. in 2014. The remainder of the island, which consists of 57 acres, and the historic St. Martin Island lighthouse are owned by the Little Traverse Bay Band of Odawa Indians.

Funding for the acquisition of St. Martin Island was provided by the Luber and Uihlein families, who generously donated a portion of the value of their lands to The Nature Conservancy, other private gifts to The Nature Conservancy, grants from the North American Wetlands Conservation Act program and the Great Lakes Restoration Initiative, and settlement funds administered by the Fox River / Green Bay Natural Resource Trustee Council.

St. Martin Island is located about five miles from Washington and Rock islands at the tip of Wisconsin’s Door Peninsula.

Public access to St. Martin Island is prohibited to protect critical habitat and historic sites, limit invasive species transport, and public safety concerns.

The Detroit Island Unit was added to the refuge in on March 28, 2019. Funding for the acquisition was provided by settlement funds administered by the Fox River / Green Bay Natural Resource Trustee Council.

This 148-acre unit is open for public access during daylight hours, Memorial Day through Labor Day. The unit is also open for deer hunting during State of Wisconsin seasons and hunters should be aware of private lands that border the refuge property.

Nearby Activities


Green Bay National Wildlife Refuge islands are closed to the public. Hog and Pilot Islands are closed to the public to reduce disturbance to nesting birds. Plum Island is currently closed to the public except for special events. The refuge is managed by staff at the Horicon National Wildlife Refuge Complex in Mayville, WI. Contact (920)387-2658 or The office/visitor center is located on the east side of Horicon Marsh, 3.5 miles south of State Highway 49 on County Road Z.

Additional Information