Bison are large herbivorous mammals belonging to the genus Bison that first appeared 3.4 – 2.6 million years ago, during the Late Pliocene or Early Pleistocene, and are still alive today. Bison are ruminant animals, which gives them the ability to ferment plant matter in a specialized stomach prior to digestion. They consume a wide variety of plants, including woody species. Throughout the year, bison shift the selection of plants in their diet based on which flora offer the highest concentrations of protein or energy at any given time. The protein levels of the plants they consume tend to peak in spring and decline thereafter, reaching their lowest point during winter. Bison are believed to migrate in order to optimize their diet, frequently focusing their grazing on recently burned areas due to the higher quality forage that grows following a burn.
