Shaped by the last retreating glacier around 10,000 years ago, the Patoka River meanders through sand, gravel and silt deposits left by glacial outwash. The river corridor is home to over 380 species of wildlife, including nesting bald eagles, the Indiana bat, the copperbelly watersnake, the great blue heron, the marbled salamander, and the Halloween pennant dragonfly. Neotropical migratory songbirds thrive in this rich ecosystem within the north-south flyway of the Wabash River Basin. Typical floodplain trees include sweetgum, swamp white oak, pin oak, and shellbark hickory. At least 20 plant species and 63 animal species considered threatened or endangered live within the river valley. Recognized as a special and fragile habitat, the Patoka River National Wildlife Refuge and Management Area was established in 1994 and now encompasses 6,600 acres of wetlands, bottomland hardwood forests, and grasslands along 30 miles of the Patoka River corridor. Its Cane Ridge unit, on the Wabash River bottoms off Gibson Lake, is significant for endangered Least Tern habitat and stands of Giant Cane, the only bamboo native to the United States. The refuge was established to provide habitat for migratory birds, increase biodiversity, restore river corridor habitats, improve water quality, develop citizen understanding and support for natural resources, and provide wildlife-related education and recreation opportunities.