Green Bay National Wildlife Refuge protects small islands in Lake Michigan near Door Peninsula and the Garden Peninsula, including all or parts of six islands. Established in 1913 with Hog Island set aside for native birds, it became the second national wildlife refuge in the Great Lakes region. Its isolated islands on the Niagara Escarpment provide important breeding habitat for migratory birds, including herons, mergansers, gulls, cormorants, and black-crowned night herons, while also supporting rare plants such as dwarf lake iris and abundant Canada yew. The refuge also preserves lighthouse sites on Plum and Pilot Islands and includes islands within the Wisconsin Islands Wilderness Area.