The Prehistoric Bison of Yellowstone National Park

Abstract

When Yellowstone National Park (YNP) was established in 1872, American bison (Bison bison) were living in the park's forests and mountains. A study conducted in the 1960s concluded that those were Mountain bison (Bison bison athabascae), a subspecies adapted to mountain habitat. It was assumed that those historical bison occupied their native habitat and had done so in prehistoric times. When archaeological evidence of YNP bison was discovered in the mid-1990s it seemed reasonable to assume that those bones were derived from a herd of native prehistoric bison. However, a review of archaeological, historical, genetic, and ecological evidence suggests a different history. Namely, herds of bison were absent before 1840. Sometime between 1840 and the mid-1850s, plains bison were driven into the mountain forest in and near YNP. In those forests, bison were relatively safe from horse-mounted, bow-and-arrow-armed Native American hunters. Archaeological evidence suggests that YNP's prehistoric bison were bulls that left herds on the low-elevation plains that surround the park; the bulls would have traveled up mountain drainages to the Yellowstone volcanic plateau. Bison played no significant role in the ecological processes that shaped YNP's prehistoric landscape. YNP's modern bison herd is causing significant changes in range condition.