MIDDLE HOLOCENE BISON IN THE UPPER MIDWEST

Comprehensive analyses of bison remains from Itasca, Minnesota, and Nye and Interstate Park, Wisconsin, offer new information on the paleoecology of the Bison “occidentalis” in the Upper Midwest. These sites are taphonomically complex attritional assemblages, not catastrophic kill sites as originally described. Ten recent AMS radiocarbon dates on bison bone collagen span about 1,500 years, from 8540 cal. B.P. to 6890 cal. B.P., and when coupled with age-frequency mortality data, indicate that the region sustained resident herds during the middle Holocene. Serial stable isotope analyses (δ¹³C, δ¹⁸O, and ⁸⁷Sr/⁸⁶Sr) of tooth enamel carbonate suggest midwestern bison at this time were not obligate grazers like contemporary animals in the Great Plains. Rather, they were flexible herbivores who were able to utilize a variety of local habitats, and did not migrate seasonally.