written by: LisaSmegal•edited by: Donna Cosmato•updated: 5/30/2011
People researching American bison information are often shocked to discover that the bison is an entirely different species than the buffalo, a species commonly confused with their large North American counterparts.
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For hundreds of years, people have often used the terms bison and buffalo interchangeably when referring to the American bison found grazing the plains of North America. From a biological standpoint however, bison and buffalo are two entirely different species.
In fact, no buffalo species can be found on the North American continent. True buffalo species are found in Asia and Africa, like the Asian water buffalo and the African Cape buffalo. The animals found in North America are technically bison, though many people still refer to them as American buffalo.
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General Bison Information
The bison is the largest land mammal found on the North American continent. Bison are scientifically classified as members of the family Bovidae. The average bison is 6 to 6.5 feet tall at the shoulder and is approximately 10 to 12 feet long from head to hind. Their weight range is typically 900 to 2,000 pounds with males larger in size and weight than females. In the wild, bison live an average of 12 to 18 years although in captivity they can have a lifespan of 30 years or more.
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History of Bison in North America
It is estimated that prior to 1830, between 30 and 60 million American bison roamed the plains of the United States. Within 50 years, the species faced extinction due to excessive hunting by American settlers. The settlers hunted the bison not only for hides, meat and sport, but also to cut off the natural resources the bison provided to the Native Americans who were highly dependent upon the animal for both practical and spiritual reasons. By 1889, where millions of bison could once be found, less than 1,000 animals remained.
Fortunately, in 1905 William Hornaday and President Theodore Roosevelt founded the American Bison Society in an effort to save the species from extinction. Today, an estimated 500,000 bison can be found throughout the United States, though the majority of these animals live on private or protected land.
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Bison Diet Facts
Bisons are herbivores or in human terms, vegetarians. Bison only eat plant materials like grasses, shrubs, herbs and even twigs. Like many members of the bovine family, bison have four stomachs that assist in breaking down hard to digest plant fibers.
Bison are also ruminant mammals. In ruminant mammals, plant-based foods are partially digested, or softened, in the first stomach. The food is then regurgitated back into the mouth so the animal may chew the food into smaller particles. This is often referred to as “chewing their cud." The food is then swallowed again, where it can be fully processed throughout the entire digestive tract.
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Habitat and Range
As herbivores, the American bison prefer areas flourishing with plant-life. In the past, bison roamed throughout the prairies, plains and river valleys of North America. Today, wild bison are limited to protected areas such as national wildlife refuges and parks including the National Bison Range in Montana, Walnut Creek National Wildlife Refuge in Iowa, Wood Buffalo National Park in Canada and Yellowstone National Park in Wyoming. Many bison herds live in other regions of the North American continent, though these herds live in captivity and are primarily bred and raised for meat consumption.
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Many people believe that the bison is an aggressive animal. Part of this belief stems from observations of the male bison during the mating season. During breeding season male bison, called bulls, display their strength in order to attract potential mates. This display includes pawing at the ground, loud bellowing mating calls and head-butting between two males. However, with the exception of this mating behavior, the bison is actually a very laid-back, gentle creature. In fact, during the Lewis and Clark expedition from 1804 to 1806, Meriwether Lewis noted in his personal journal “we saw a great quantity of game today particularly Elk and Buffaloe, the latter are now so gentle that the men frequently throw sticks and stones at them in order to drive them out of the way...".
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Reproduction and Mating Habits
Female bison reach sexual maturity between two and three years of age. However, males do not reach sexual maturity until about six years of age. During the mating season, which generally runs between July and September, male bison will begin to migrate towards a group of females to seek out potential mates. When the male finds the female he wants to breed with, he will begin to “tend" the female.
When a male tends a female, he positions himself in such a way that he separates her from the rest of the heard. If other males come too close to his chosen mate, he may threaten and attack in order to protect his “claim." Tending can last from a few minutes to several days, depending upon whether the female is interested in the particular male that has “chosen" her for breeding.
After breeding, the female gives birth to a calf in approximately nine months. Multiple births are rare in the American bison species. Prior to birth, the female will isolate herself from the rest of the herd and will remain isolated until the calf is a few days old.