Bison are the largest land mammal in North America – bigger than elk, moose, and grizzly bears! The male bison is called a bull. Mature bulls weigh up to 2000 pounds and stand as high as six feet at the hump – this is bigger than some sports cars. Female bison, called cows, are smaller than males, weighing as much as 1,000 pounds and standing about five feet at the hump. Bulls and cows living in natural settings have a lifespan of 12 to 15 years, but may live twice as long. An exceptionally hardy animal may live up to 40 years. Both cows and bulls have two black horns. The tips are sharp and grow throughout their lifetime. They never shed nor drop off like antlers. These horns are made of the same material as human fingernails but are thicker and stronger. Their thick coats act as protective blankets – the cold doesn’t get in and the buffalo’s body heat doesn’t get out.