The CSKT Bison Range is a nature reserve on the Flathead Indian Reservation in western Montana established for the conservation of American bison. Formerly called the National Bison Range, the size of the bison herd at the BR is 350 adult bison and welcomes 50–60 calves per year. Established as a National Wildlife Refuge in 1908, the BR consists of approximately 18,524 acres within the Montana valley and foothill grasslands.