Reintroduction of Bison to Iowa: Quick Facts

  • Plains bison are the largest native herbivore on the contemporary Great Plains. Adult bulls weigh 1,800 to 2,000 pounds, with a shoulder height of 5.5 to 6.5 feet. Cows weigh around 1,000 pounds with a shoulder height of 4.5 to 5.5 feet. Both sexes have horns.
  • Adult bison consume more than 30 pounds of grass (air-dry weight) in a day.
  • Bison have poor eye sight, but are highly mobile with a keen sense of smell. They can run at speeds up to 35 miles an hour.
  • Bison can jump 6 feet vertically and more than 7 feet horizontally.
  • Bison are powerful swimmers, navigating with all but hump, muzzle, and top of the head submerged.
  • In wild herds, few animals reach old age (15-20 years), but in managed herds, bison regularly attain these ages.
  • Single calves are normally born in April to June, following a 9 ½ month gestation period. Bison rarely have twins.
  • Cows continue to breed into their 20s, while most successful breeding for bulls is done by those in the 6 to 10-year old age group.


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