Genus: Bison
Species: bison

Bison bull

This animal's true name is the American bison, but most people call them buffalo. They are the largest terrestrial animal in North America.

Bison once dominated the grassland and prairie ecosystems of the United States.  When the first explorers came to the Great Plains, it is estimated that at least 30 million bison roamed the land.  By 1900, a little over 1,000 bison could be found with only a handful of wild bison left in Yellowstone National Park.  What happened to the bison?

Even with speeds of over 30 miles an hour, bison could not outrun hunters.  Some bison were killed for food, but often they were killed in large numbers just for fun.  In addition, starting after the Civil War, bison were exterminated to make way for farmland as people settled the Great Plains. 

The 1900’s brought a change of fortune to the bison.  Conservationists, ranchers and land owners began to see the importance of the bison to the American west ecosystem and indigenous cultures. They were bred, protected on federal lands and brought back from the brink. 

Learn more about NWF's work restoring bison to the American West>>

Description:  It is very hard to mistake a bison.  Along with their formidable size, bison have several unique traits that help to identify them.  One of the most noticeable is the hump on their shoulders. 

Bison have deep brown fur.  The fur can grow very long, especially around the face and head.  Bison also grow a long beard and mane. 

The head of a bison is very large with a thick skull.  They use their heads to fight by crashing into one another.  Bison also fight using their horns.   Both male and female bison have short, curved, and black horns.  They can grow to 2 feet long. 

Size:  Bison are big…really big!  Bison are the largest terrestrial animal in North America.  They can be over 6 feet tall.  A male can weigh upwards of one ton and a female can weigh about 900 pounds.  That’s one large animal!

Diet:  The American bison are herbivores.  They like low growing grasses and sedges.  Bison are constantly on the move and they even walk while they eat!

Typical Lifespan:  The average bison that survives to adulthood can live around 20 years.  Captive-raised bison typically live longer. 

Habitat:  American bison like open plains, savannas and grasslands.  

Range:  Before human intervention, bison once ranged over much of North America, including central Canada and most of the interior U.S.  The only places free of bison were along the coasts and deserts. 

Today, bison are only wild in national parks, state parks and reserves.  Your best chance of seeing wild bison are to visit Yellowstone National Park or Wood Buffalo National Park of Canada.

Communication:  Bison communicate by hearing and smell.  The most important communication is done with pheromones and smells, especially during reproduction.  Bison also grunt, snort and growl. 

Bison calf

Life History and Reproduction:  American bison like to live and travel in groups.  For most of the year, herds are divided by sex with females and calves in one herd and males in another herd.  When the breeding season begins in the summer, many males temporarily join the female herd and begin looking for a mate. 

The dominant bulls (male bison) choose a female and defend her against other males through fighting.  The males might butt heads or use their horns.  Once the female agrees to mate, the pair mates several times.

The cows (female bison) are pregnant throughout the fall, winter and early spring.  The calves are born in mid-spring to increase the likelihood of surviving the next winter.  Most cows only have one offspring.  Each calf weighs about 50 pounds and has reddish fur.  Within an hour after birth the calf stands and, soon after, begins to walk. 

The cows will care for their young for about a year - however, the calves learn to be independent pretty quickly.  By the middle of their first winter, juvenile bison are feeding independently and have the typical brown fur of the adults.   It will be 2-3 years for the females, and upwards of 6 years for the males, until they can breed themselves.

Bison exhibit some odd behaviors throughout the year.  They roll around in dirt, create depressions (wallows) in soil with their immense weight and take dust-baths.  Bison even rub their horns on trees!

Winter can be very hard on bison.  The cold and lack of food can take its toll, especially if the bison is sick, injured, young or old.  Very young bison have the highest risk of dying over the winter.  Despite their immense size, bison still have to worry about predators.  Buffalo calves can easily become the prey of a wolf pack or grizzly bear

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