Fish and Wildlife Service, Indiana.
Big Oaks National Wildlife Refuge encompasses 50,000 acres in Jefferson, Jennings and Ripley counties. The refuge covers a portion of the former Jefferson Proving Ground, a munitions testing facility operated by the U.S. Army between 1940-1995. In 1996, the U.S. Fish and Wildlife Service began managing the wildlife resources of the proving ground. Big Oaks National Wildlife Refuge was established in June 2000 as an "overlay" national wildlife refuge and now operates under a 99-year real estate permit from the Army. The Indiana Air National Guard still operates an air-to-ground bombing range on 1,033 acres of the former proving ground and this property is surrounded by, but not part of, the refuge.
The refuge is designated as a Globally Important Bird Area and contains many rare species of plants and animals in the wetlands, grasslands, shrublands and forest. The refuge hosts one of the world's largest populations of Henslow's sparrows with over 500 pairs nesting on the refuge. There are at least 32 caves found on the property that provide habitat for rare invertebrate species. The wet flatwoods forests of the refuge shelter rare salamanders and several endangered bats during the warm months of the year. Some significant historic buildings and stone bridges are present on the refuge along with the a 165 acre lake (Old Timbers Lake).
The entrance to the refuge is on U.S. Highway 421, on the former Jefferson Proving Ground, five miles north of Madison, Indiana. Enter at the main entrance of the former Jefferson Proving Ground and follow the brown directional signs to Big Oaks office.