A special episode on American bison. While big herds are coming back from near extinction a century ago, restoring these iconic animals is a complex and ongoing challenge. For the Crow Indians, the buffalo was far more than a source of food and clothing, and it still plays a key spiritual role in their culture. How are bison herds and tallgrass prairie conservation linked together? Ranchers and restaurants create a market demand for bison that could guarantee their survival for future generations. Linguists learn more about hand signing from newly discovered old films showing the use of intertribal sign language.