Holocene bison in the Great Basin, western USA

Bison (Bison bison) were widespread in the eastern and northern parts of the Great Basin (the area of internal drainage in the arid western USA) during the late Holocene, particularly after 1600 C-14 yr BP. However, of the four areas within the Great Basin for which there is anecdotal evidence of the historic presence of these animals, only one - south-central Oregon - has provided compelling empirical data in support of that evidence. Bison populations flourished in the area immediately surrounding the basin of Pleistocene Lake Bonneville between c. 1600 and 600 C-14 yr BP, a fluorescence that seems to have been tied to deeper northwards incursions of monsoonal storms. Once those incursions weakened, bison populations declined substantially in size. The appearance of bison in south-central Oregon after 500 C-14 yr BP may be a function of the increased winter moisture and cooler temperatures that marked this region during the 'Little Ice Age'.