Biogeography of Holocene bison in the Greater Yellowstone Ecosystem

The role of bison in the pre-Euroamerican settlement of the Greater Yellowstone Ecosystem (GYE) has been debated for decades by biologists, historians, and archeologists. However, we do know that bison have been a member of the regional ecosystem for more than 10,000 years. Despite this long-term presence, knowledge of their ecology has largerly been gained through the study of modern herds who have been subjected to various management practices for over 100 years. In this study, I examine the Holocene record of bison from the region to reconstruct their relative abundance through time in the context of Holocene climate models. More detailed analysis of individual bison was also conducted. Craniometric analysis of 10 bison suggests a bull-dominated assemblage. The demographics of these individuals may be reflective of a larger hunting pattern of either pursuing lone bulls or an encounter-type hunting pattern. Discriminat fuction analysis of these crania was also conducted and suggests possible genetic isolation of mountain populations. Stable carbon and oxygen stable isotope analysis of downtooth samples from third molars of precontact and modern individuals were also conducted. The sample includes 14 individuals from eight archeological sites in the GYE that range from the early Holocene Horner site on the western edge of the Bighorn Basin to the late Holocene bison from the Goetz site in Jackson Hole. Three modern individuals from Yellowstone National Park and two individuals from the Henry Mountains, Utah were also analyzed. Each of the individual stable isotope data provides a pattern that is probably reflective of seasonal use of available vegetation and water sources. While each of the Holocene individuals illustrates greater variability than the modern samples, the early Holocene Horner site individuals have the greaterst variability. The results of this analysis suggest variability of bison migration patterns that may be reflective of the influence of large-scale climate patterns on vegetation and the behaviorial response of these individuals to resource availability.