American Bison

Bison live in small herds of approximately fifty animals. The herds provides defense against predators such as wolf and coyote. Although the bison's senses of smell and hearing are sharp, its vision is poor. Since bison often do not recognize danger until it is too late to flee, the females will surround their young and the bulls will surround the females, shielding them from their attackers. Bison spend most of the day grazing in small groups. But where the grazing is particularly good, and during the two annual migrations, hundreds of bison may gather together to feed. They also take frequent mud or dust baths. The bison is adapted to withstand the great temperature extremes of its range, which once extended from Canada to Mexico. It grows a dark, warm, shaggy coat which is shed each spring. It is replaced by a shorter, lighter summer coat.

Bison communicate by hearing and smell. The most important communication is done with pheromones and smells, especially during reproduction. Bison also grunt, snort and growl.

For most of the year, females and young males live together in small herds. Mature bulls either live alone or band together in smaller groups. During the mating season from July to September, the bulls fight over those females that are ready to mate. In her prime, a female will calve every other year. Rival males attempt to warn one another off by stamping the ground and bellowing loudly. If neither bulls backs down, they will charge each other, butting their heads together in a contest of strength. The winner will mate with the female and stand guard over her for several days. Calves weigh about 65 pounds at birth and are able to stand within a few hours.

The bison feeds mainly on grass and other succulent vegetation. Methodical grazers, a herd can cover up to 2 miles a day in in search of grass. Food is chewed and swallowed, then regurgitated and chewed again. This method of digestion is known as rumination, more commonly called chewing cud. In addition to its daily forages, the bison also makes seasonal journeys in search of fresh pastures. Before its numbers were reduced, the bison migrated in vast herds, moving north in spring and south in fall. Today, although its range is far more limited, bison in Alberta, Canada still migrate 150 miles each spring and fall.