Fort Niobrara National Wildlife Refuge in Nebraska protects 19,131 acres along the Niobrara River, where limestone cliffs, prairie, and wooded ravines create an unusually diverse Great Plains habitat. The site began as the Fort Niobrara Military Reservation, a U.S. Cavalry post from 1879 to 1906, and part of it became the Niobrara Reservation in 1912 before evolving into a wildlife refuge. More than 230 bird species have been recorded there, and it is especially known for its bison herd, established in 1913 to help restore a native animal to the region. In 1976, 4,635 acres became the protected Fort Niobrara Wilderness.