Unlike cattle, bison can produce calves for 20 years or more.
- Female bison breed when they are 2 years old and have their first calves when they are 3.
- Cows can live to be 20 to 25 years old, having a calf each year under the right conditions.
- The gestation period for the American Bison is 9 1/2 months. Under normal conditions, cows have their calves from mid-April through June. Cows generally have one calf a year, but twins sometimes occur.
- The calves are small when born, normally weighing between 25 to 35 pounds. Although small, these little critters are tough and are up walking and running with their mothers within a couple of hours.
- Cows are protective of their young. They leave the herd to have their calves and then remain away from the herd for between six hours to several days.
- Bison calves are normally weaned when they are around 6 months old. By then, the females generally weigh around 350 pounds and males weigh 425 pounds.
- Under range conditions, bison cows seldom have calving problems.
- The bull-to-cow ratio for bison is approximately one bull per 15 cows.
- Buffalo have not been successfully artificially inseminated on a consistent basis.