Following the Herd
A look into the History, Endangerment, and Reemergence of the American Bison
American bison once dominated the North American landscape. Before human settlement, tens of millions of bison freely roamed across the continent. Over the past 150 years, however, the once-plentiful mammals have neared extinction and have been a leading species on the topic of endangerment and conservation [1]. Many people still believe that the great American mammal is on the brink of disappearing, but is this the case? Let's take a look at the history of the American bison and answer the question: What really is the status of bison?
Home on the Range
History of American Bison
"Herd of bison, near Lake Jessie" 1855
American bison have had a long history. A significant part of not only the North American ecosystem, but also a major aspect of Native American cultures, traditions, and livelihood, bison faced an ever-increasing threat as European settlers began expanding westward. As new dangers were introduced, the American bison population dwindled and their natural range deteriorated through time.
Historic Range
Since 1500
American bison were once a prominent sight in much of North America. Historical estimates cite that 15-60 million bison roamed across the continent [2], spanning across 22 major biomes and encompassing nearly two-thirds of North America [3].
1800
By the turn of the 19th century, many bison still freely inhabited the North American Plains. Population estimates based on historical records place the species numbering in the 10s of millions, however much of the extent of bison had been reduced to the central region of the continent [4].
1825
As the century progressed, American bison began to encounter their newest and most lethal threat: American settlers moving westward. By 1825, the United States had expanded west to the Mississippi River. This newly established land created an overlap between the United States' Midwest territory and the Eastern-most extent of American bison. The meeting of bison and American pioneers provoked competition for land and granted access to a valuable new resource for hunters and industrialists.
1850
At the middle of the 19th century, American bison faced immense pressure forcing their extent to further diminish. By this time, the United States was moving farther westward and increasingly encroaching on bison territory. Arkansas and Texas received statehood in 1836 and 1845, respectively. And, as Native Americans were forcibly moved to new areas of the Great Plains, new landscapes and needs to hunt bison arose. Additionally, on the southwest side of the bison's range, New Mexican bison hunters called ciboleros were active in slaughtering 15,000-20,000 bison a year [5][6].
American bison were also strained under natural conditions - the Southern Plains began to experience a drought in 1846 - and competition for resources with invasive wild horses [5].
1850 - 1875
During the latter half of the 1800s, bison experienced increased levels of hunting. Much of the threats that affected bison populations for the past century began to reveal their repercussions during this period. Additionally, during the 1870s, the U.S. Army enacted strategies of exterminating bison in order to weaken the resources of Plains Indians in hopes of gaining territory for settlement and railroads [5].
"The far west - shooting buffalo on the line of the Kansas-Pacific Railroad" 1871
1875
By this year, the cost of excessive hunting and the changing scene of westward expansion had taken its toll. With the completion of the Transcontinental Railroad in 1869, the American bison were split into two separate populations (seen in the map). As the century would progress, bison would promptly face the culmination of its threats and pressures: Near Extinction.
Near Extinction
Endangerment of American Bison
By the late 19th century and into the 20th century, the American bison population plummeted to dangerously low numbers. The scope of this centuries-long and continental-sized degression has had such a lasting impact that, even today, the near extinction of bison is one of the species' most well-known characteristics.
1889
Less than 1,000 bison remain in North America [4][7].
1894
The only known wild bison herd in the United States remains at Yellowstone National Park [5].
1900
The bison population lingers at its lowest point of fewer than 1,000 [4].
Roaming Free
Reemergence of Bison Populations
For many people, the story of American bison is left unconcluded at near extinction. Because of the species' notorious and commonly taught depletion in size and number, a considerable amount of people are left to wonder what ever happened to the United States' national mammal. Are they still endangered? Did they go extinct? Who, if anyone, conserved the North American giant?
Recognizing the diminishing population of bison, The United States government, headed by Theodore Roosevelt, created the American Bison Society in 1905. The ABS overlooked the conservation of bison herds, including the pivotal herd that remained in Yellowstone National Park [8]. With the efforts of the ABS, and private ranchers and wildlife refuges, American bison finally began to see an increase in total population.
Today, bison have a much brighter outlook. American bison currently hold a conservation status of Near Threatened, which is only one rank below the highest available status of Least Concerned [9]. In the United States, there are approximately 530,000 bison (including 30,000 in conservation herds) [10].
The status of American bison has significantly increased since the species' lowest recorded estimate of less than 1,000 in 1900. Thanks to conservation efforts, it is now possible to visit protected bison herds across North America. The map below shows individual bison observations from 1970-2023.
Expand the map to zoom in and observe bison observations. Click on states or provinces to see the total observations.
Bison Observations in North America (1970-2023)
Health of the Herd
Current Status and Future Challenges
The once nearly extinct American bison experienced one of the most notable conservation success stories. Though the great North American mammal has evaded endangerment, the species still faces prevailing challenges.
One topic of discussion with the current bison population is the restoration of the animals' natural roaming range. The strides taken to maintain and rebuild the American bison population are a profound achievement. However, only about 6% of bison are in conservation herds, of which most are isolated groups roaming on a small portion of the species' original range. Organizations such as the Wildlife Conservation Society are taking action to restore the ecological health of American bison [8].
Another concern for the future of American bison is genetic diversity. Because of the dwindling numbers of bison in the 19th and 20th century, many herds were hybridized with cattle. This has resulted in a limited amount of pure American bison in North America [7].
