American bison are majestic looking animals, with dark chestnut brown hair. They have longer, darker hair around their head, shoulders, and chest. They have a pair of upward-curved horns and a large shoulder hump. Within herds, individual bulls form and defend a group of females and will chase away any rival bulls who challenge them.
Bison form maternal groups of 16 to 25 individuals. These groups include females of various ages and young bulls up to three years old. Adult males remain on the periphery of the group. Bison also form larger herds, within these herds the boundaries between maternal groups become blurred. Groups of males also form within herds, consisting of 10 to 12 bulls.
Millions of bison used to roam North America's grasslands, boreal regions, and scrublands but the relentless slaughter of bison for meat, hides, and sport drove the species to the brink of extinction. During the last few decades of the 1800s, over 30 million animals were destroyed. By 1900, only 800 bison remained in the wild. This mass killing not only gravely endangered the bison, but also brought an end to a way of life for many Native Americans, whose entire subsistence was integrated with the lives of bison herds.