American bison are sexually dimorphic (there are two distinct gender forms). The male bull is larger than the female cow and has a massive head and shoulders. Bison have long, shaggy, coarse hair on their head, shoulders, and front legs. The hair on the back half is significantly shorter, becomes thick in winter, and is shed in spring and summer. Their coloration is shades of reddish-brown to black. Newborn calves are bright reddish-brown. They develop a chocolate-brown to black coat during maturity. The coat fades to a lighter tan with age. The pelt often turns a light yellow-brown in spring. Both males and females have horns that are relatively short and thick at the base. The horns are hollow and permanent, and they taper and curve to a sharp point. Horns begin to grow at two months of age on both sexes; males’ horns are larger. Both sexes have a distinctive hump that makes raising their head above shoulder level impossible; calves have no hump.

American bison were once near extinction after being hunted extensively for meat, hide, and sport. At one point, their entire population was down to less than 1,000 individuals. There are now an estimated one million bison on private ranches and farms within the United States.

• Listed as “near threatened" on the IUCN Red List (International Union for Conservation of Nature and Natural Resources).
• American Bison Society

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