Big Oaks National Wildlife Refuge encompasses 50,000 acres in 3 counties (Jefferson, Jennings, and Ripley) and overlays that portion of the former Jefferson Proving Ground that lies north of the historic firing line where munitions were once tested. The Indiana Air National Guard operates an air-to-ground bombing range on the remaining 1,033 acres of the former proving ground north of the firing line and this property is surrounded by but not designated as part of the refuge. Jefferson Proving Ground was established by the Army in 1940 as an ordnance testing installation and closed in 1995. Beginning in 1996, the U.S. Fish and Wildlife Service managed the wildlife resources of the proving ground. Big Oaks Refuge was established in June 2000 as an “overlay” national wildlife refuge through a 25-year real estate permit from the U.S. Army. As an overlay refuge, the Army retains ownership and the Fish and Wildlife Service manages the property as Big Oaks National Wildlife Refuge. Our mission is to preserve, conserve, and restore biodiversity and biological integrity for the benefit of present and future generations of Americans. Big Oaks Refuge provides food and shelter for a wide variety of plant and animal species. More than 200 species of birds and 46 species of mammals are found on the refuge. Stream corridors and forested areas on Big Oaks Refuge provide excellent habitat for the federally-endangered Indiana bat, which uses the refuge for summer foraging, roosting, and for rearing young. The refuge also supports breeding populations of the state-endangered river otter that were reestablished here in 1996. More than 500 pairs of state-endangered Henslow’s sparrows are estimated to breed in the large grasslands of Big Oaks Refuge. The refuge has been designated as a “Globally Important Bird Area” because of its value to Henslow’s sparrows and other migratory birds. Bald eagles and golden eagles are also known to use the refuge as a wintering site.