This male American bison at the Natural Bridge Wildlife Ranch near San Antonio looked dangerous. I believe he is a wood bison because of his tall, square hump. This subspecies is the heaviest and averages up to 2,000 pounds. In the 15th century, it is estimated sixty million buffalo roamed the United States. By 1890, after extensive hunting, that population dropped to 750 animals. Today, only about 15,000 live in the wild.