Bison

Does any one know when and/or why we started calling them buffalo?

I found this info
Bison came to North America during the Pleistocene Epoch via the Bering land bridge. Eventually they ranged from Canada’s Great Slave Lake to Mexico and from eastern Oregon almost to the Atlantic. They especially thrived on the Great Plains where some 30 million formed the biggest mass of large mammals ever to tread the globe. Early French settlers who saw herds living near the East Coast called them bison because they looked like a European cousin. A later English naturalist described them as buffalo which name stuck, even though the term is more correctly applied to other types of wild oxen found in Asia and Africa. Bison are susceptible to tuberculosis, anthrax, and brucellosis. Since these diseases theoretically can be transmitted to domestic livestock, ranchers (near Yellowstone Park for instance) become upset when buffalo wander onto private land.
at http://www.oaklandzoo.org/atoz/azbison.html