American Bison

Though not particularly known as high altitude animals, bison in the Yellowstone Park bison herd are frequently found at elevations above 8,000 feet .
Bison are among the most dangerous animals encountered by visitors to the various U.S. and Canadian national parks and will attack humans if provoked. They appear slow because of their lethargic movements but can easily outrun humans—bison have been observed running as fast as 40 miles per hour (64 km/h).

Between 1980 and 1999, more than three times as many people in Yellowstone National Park were injured by bison than by bears. During this period, bison charged and injured 79 people, with injuries ranging from goring puncture wounds and broken bones to bruises and abrasions