Each November Custer State Park conducts a buffalo auction to keep herd numbers in check with the available rangeland forage. Between 250 and 400 buffalo and a few burros are sold at this auction. Buyers and the public are invited to view the auction. Info: (605) 255-4515 or website. Funds generated from the sale help support the operation of the state park system. The sale has played an important role in establishing herds of buffalo throughout the United States. Buffalo, which once faced extinction, now the number reaches over 250,000.