The Holocene History of Bison in the Intermountain West: A Synthesis of Archaeological and Paleontological Records from Eastern Oregon

摘要

Intermountain West bison abundance and chronology is much debated, but little work addressing these debates has occurred in eastern Oregon. Historic records indicate bison were absent from eastern Oregon at Euro-American contact. However, during explorations in eastern Oregon in 1826 Ogden reported bison skeletons in a dry lake bed, suggesting bison once lived in the area.This study reviews archaeological and paleontological records, and ethnohistoric accounts of early 19th century explorers, to synthesize the Holocene history of bison eastern Oregon. Bison NISP (number of identified specimens) was documented from site reports when available, and overall abundance was measured by number of sites and number of dated components containing bison. Optimal foraging theory suggests archaeofaunal assemblages can be used to determine abundance of high-ranked prey such as bison in the paleoenvironment. To determine bison chronology for undated archaeological and paleontological contexts, 15 bison bone samples were selected for AMS dating.In total, 136 archaeological site reports were reviewed, 102 include discussions of faunal analysis, and 20 provide evidence of bison. Two paleontological records provided sufficient data to include in this study. Bison NISP values were relatively small and in reports offering quantitative faunal data, bison represented a minimal percentage of the total mammalian assemblage. Of the AMS results, five were problematic and excluded from the study, and ten provided unambiguous ages ranging from 800-160 BP. Previously published dates in conjunction with new AMS dates support a late Holocene presence of bison in eastern Oregon. Bison are present, yet scarce, in the early Holocene and altogether absent between 7,000-3,000 BP.Research results for this study are similar to those from other Intermountain West regions. Research suggests large ungulates such as bison were never abundant in the Intermountain West due to environmental constraints. Grassland degradation caused by the introduction of cattle provides proof that the region is inappropriate for large grazing herds. Understanding the prehistory of bison in the region has implications for management of modern herds as well as grassland conservation issues.