Wild Horse Island, the largest island in Flathead Lake within the Flathead Indian Reservation, has long been significant for both human use and wildlife. For centuries the Salish and Kootenai pastured horses there for protection from theft, giving the island its name. After reservation lands were divided in 1904, failed agricultural development and timber cutting damaged native vegetation, yet the island still preserves one of Montana’s last shortgrass prairies. Protected as a state park since 1977, it is managed to prevent overgrazing and is especially known for its bighorn sheep herd, along with mule deer, waterfowl, bald eagles, and wild horses in a glacially shaped landscape.