The Joseph H. Williams Tallgrass Prairie Preserve, in Osage County, Oklahoma near Foraker, Oklahoma, is the largest protected tract of tallgrass prairie in the world. Managed by The Nature Conservancy, the preserve contains owned by the Conservancy and another leased in what was the original tallgrass region of the Great Plains that stretched from Texas to Manitoba. Description The preserve is located at the southern end of the Flint Hills, also known as the Osage Hills. The rocky, rolling prairie stretches from northern Kansas into Oklahoma. Exposed limestone formations make cultivation difficult, and thus the Flint Hills have survived much as they were when they were a hunting ground for area tribes such as the Wichita, Osage, and Kaw. The region is called “The Osage” by Oklahomans, referring to the name of the Native American tribe that occupied this territory and to the county named for them. Pilots call The Osage the “Black Hole” when flying over it at night because it is so lightly populated. The preserve is bisected by the well-timbered Salt Creek and its tributaries. The eastern portion of the preserve is in the Cross Timbers, a north-south running belt of tangled oak forests that were a major impediment to early travelers heading west. About 10 percent of the preserve is forested and the remainder is tallgrass prairie; the grasses of several species here can grow tall. The tallgrass prairie owes its existence to fire, whether caused by lightning or manmade. Without fire, the prairie quickly becomes brushland. The Native Americans were aware of this and burned the prairie regularly to nurture new growth of succulent grasses and to kill invasive trees and shrubs. The Nature Conservancy has continued this practice with a process called “patch burning,” in which about one-third of the prairie is burned each year. This process has proven beneficial not only in providing grazing for bison and cattle, but also for the habitat of the threatened greater prairie chickens, which also inhabit the preserve in small numbers. Bison are the most prominent attraction of the preserve. Bison are rounded up each fall and the excess numbers sold. Cattle are grazed on . The preserve supports 755 plant species, many unique to the tallgrass prairie, and more than 300 bird species. Forest trees include several species of oak, cottonwoods, ash, red cedar, elm, sycamore, and others. The Tallgrass Prairie Preserve is on what used