Thousands of Sandhill Cranes, ducks, shorebirds and some endangered Whooping Cranes use this important bird area. This 32,197-acre refuge located in north-central Oklahoma, is made up of a variety of habitats such as wetlands, prairie and about 12,000 acres of salt flats. Majestic and wide open, the salt flats are the only place in the world where you can dig for hourglass selenite crystals.