He needs to eat an awful lot of grass

This is one of the Bison that friends from England and I saw during our time in Yellowstone National Park. These animals are just huge and powerful - was so thankful for full zoom : ) We waited and waited for his head to be raised, but this animal just kept eating. Our week away, 11-17 September, took us down to Grand Teton National Park as well, returning to Calgary via Waterton-Glacier International Peace Park.

"The bison (Bison bison) is the largest land mammal in North America. In a typical year, more than 3,000 bison roam the grasslands of Yellowstone National Park. Bulls are more massive in appearance than cows, and more bearded. For their size, bison are agile and quick, capable of speeds in excess of 30 mph. Each year, bison injure park visitors who approach too closely.

Most animals in Yellowstone are subject to different management goals when they leave the park. Bison require special attention because many have been exposed to the bacteria that causes brucellosis, a disease that also infects domestic cattle. Yellowstone has worked with the state of Montana and other federal agencies to develop a plan for managing the bison population in a way that protects both its wild and free-roaming characteristics and the health of Montana cattle.

Yellowstone is the only place in the lower 48 states where a population of wild bison has persisted since prehistoric times, although fewer than 50 native bison remained here in 1902. Fearing extinction, the park imported 21 bison from two privately-owned herds, as foundation stock for a bison ranching project that spanned 50 years at the Buffalo Ranch in Yellowstone's Lamar Valley. Activities there included irrigation, hay-feeding, roundups, culling, and predator control, to artificially ensure herd survival. By the 1920s, some intermingling of the introduced and wild bison had begun. With protection from poaching, the native and transplanted populations increased. In 1936, bison were transplanted to historic habitats in the Firehole River and Hayden Valley. In 1954, the entire population numbered 1,477. Bison were trapped and herds periodically reduced until 1967, when only 397 bison were counted park wide. All bison herd reduction activities were phased out after 1966, again allowing natural ecological processes to determine bison numbers and distribution. Although winterkill takes a toll, by 1996 bison numbers had increased to about 3,500."

www.nps.gov/yell/naturescience/bison.htm