5.5 to 6.5 feet (1.7 to 2 m)
9.8 to 11.5 feet (3 to 3.5 m)
1,000 to 2,200 lbs (450 to 1,000 kg)
Weight (Males)
800 to 1,000 lbs (360 to 450 kg)
Weight (Females)


#Herbivore #Mammals

The American Bison, often simply referred to as bison, holds a significant place in North America’s natural and cultural history. It is a species of large, herbivorous mammal belonging to the Animal Kingdom, specifically to the class Mammalia, order Artiodactyla, and family Bovidae. Bison are closely related to domestic cattle, buffalo, and other bovid species.  The Bison is a symbol of the American West, renowned for its massive size, shaggy coat, and iconic presence on the prairies and grasslands of North America.

Bison are large, hoofed mammals characterized by their robust build, broad heads, and distinctive shoulder humps, which are composed of muscle and provide additional strength for foraging through snow and vegetation. They have a shaggy coat of fur, ranging in color from dark brown to reddish-brown, with a lighter underbelly. Both males, known as bulls, and females, known as cows, possess curved horns, although those of bulls are typically larger and more massive.

Historically, Bison roamed vast expanses of prairies and grasslands across North America, forming large herds that migrated in response to changing seasons and food availability. Today, they are primarily found in protected areas such as national parks, reserves, and private ranches, where they graze on grasses, sedges, and other vegetation. Bison are social animals, forming cohesive herds led by dominant bulls that defend territories and mating rights.

Bison are herbivores, feeding primarily on grasses and sedges, which make up the bulk of their diet. They are well adapted to grazing on tough, fibrous vegetation, using their large, muscular tongues and powerful jaws to tear and chew plant material. Bison are considered ecosystem engineers, as their grazing behaviors shape the landscape and create habitat diversity for other species.

Conservation Status

The conservation status of the Bison varies depending on the population and geographic location. The American Bison, also known as the Plains Bison, is listed as near threatened on the International Union for Conservation of Nature (IUCN) Red List. This classification reflects the historical decline of Bison populations due to overhunting, habitat loss, and fragmentation.

However, concerted conservation efforts, including reintroduction programs, habitat restoration, and sustainable management practices, have led to the recovery of Bison populations in some areas. Despite these successes, ongoing conservation efforts are necessary to ensure the long-term survival of Bison and their ecosystems

Critically Endangered
Near Threatened
Least Concern

Physical Characteristics

The American Bison, often simply called bison, is a large and robust herbivorous mammal known for its distinctive appearance. Here are its physical characteristics:

Physical Appearance:

  • Bison have a massive, humpbacked body covered in shaggy, dark brown fur. Their fur provides insulation against harsh weather.
  • Their heads are large and somewhat triangular, with a prominent forehead covered in a thick mane of hair.
  • Both males (bulls) and females (cows) have short, curved horns that point upward and inward. These horns can grow up to 2 feet (0.6 meters) in length.
  • Their legs are relatively short and sturdy, supporting their massive body weight.

Size and Weight:

  • Bison are among the largest land mammals in North America.
  • They typically measure about 5.5 to 6.5 feet (1.7 to 2 meters) in height at the shoulder.
  • Adult bison can reach lengths of 9.8 to 11.5 feet (3 to 3.5 meters) from nose to tail.
  • Adult males (bulls) weigh between 1,000 to 2,200 pounds (450 to 1,000 kilograms), while females (cows) are slightly smaller, ranging from 800 to 1,000 pounds (360 to 450 kilograms).

These physical characteristics, including their size, shaggy fur, and distinctive horns, make bison easily recognizable and contribute to their iconic status in North American wildlife.


The reproductive cycle of American Bison, commonly referred to as bison, follows a specific pattern:

Breeding Season:

  • Bison typically mate during the summer months, with the peak of the breeding season occurring in late July and August.
  • During this time, male bison (bulls) engage in vigorous displays of dominance and compete for the attention of receptive females (cows).
  • Dominant bulls establish and defend mating territories, known as “lekking grounds,” where they attempt to attract and mate with multiple females.


  • The gestation period for bison, which is the time between fertilization and birth, is approximately 9.5 months. Gestation can range from about 266 to 300 days, with slight variations among individuals.


  • Female bison (cows) give birth to a single calf, although rare occurrences of twins have been reported.
  • Calves are usually born in late spring or early summer, typically from April to June, depending on regional climate and food availability.
  • Bison calves are precocial, meaning they are relatively well-developed at birth and can stand and walk shortly after being born.
  • The mother (cow) is highly protective of her calf and will defend it against potential threats, including predators.


  • Calves are nursed by their mothers for several months, typically until they are around 7 to 8 months old. During this time, they gradually transition to a diet of grass and other vegetation.

The reproductive cycle of bison plays a vital role in maintaining their populations. The timing of births aligns with the availability of nutritious forage in their habitats, ensuring the best chances of survival for the young calves.


The lifespan of American Bison, commonly known as bison, can vary depending on whether they live in the wild or in captivity, as well as other factors such as food availability and predation risk.

Wild Bison:

  • In the wild, the average lifespan of bison is typically around 15 to 20 years.
  • Calves face a higher mortality rate due to predation and environmental factors, but those that survive their first year have a good chance of reaching adulthood.
  • Adult bison in the wild may succumb to predation by wolves or grizzly bears, harsh winters, disease, or accidents.

Bison in Captivity:

  • Bison in captivity tend to have longer lifespans compared to their wild counterparts. They can live into their mid to late twenties and sometimes even longer.
  • In captivity, they are protected from natural predators, provided with consistent access to food and veterinary care, which contributes to their increased longevity.

Threats to Bison:

  • Historically, unregulated hunting and habitat loss were the primary threats that led to a drastic decline in bison populations in the 19th century, nearly pushing them to extinction.
  • Today, conservation efforts and protected areas have helped bison populations recover, but they still face challenges such as habitat fragmentation, disease (such as brucellosis), and competition with livestock for grazing resources in some regions.
  • Climate change, which can alter the availability of forage and water, also poses a potential threat to bison and their habitats.

Overall, the conservation status of bison has improved significantly, but ongoing efforts are necessary to ensure the continued survival of these iconic North American animals.

Eating Habits

American Bison, commonly referred to as bison, are herbivorous mammals with specific eating habits suited to their grassland and prairie habitats. Here’s a description of their eating habits:


  • Bison are primarily grazers, which means they primarily consume grasses as their main source of food.
  • They feed on a variety of grass species, preferring fresh, green grasses during the growing season when they are most nutritious.
  • During the winter months or in times of food scarcity, bison may also consume dry grasses and other vegetation, such as sedges, forbs, and shrubs.
  • Their ability to switch between different plant species allows them to adapt to changing food availability throughout the year.

Foraging Behavior:

  • Bison are known for their massive size and strong, muscular necks, which they use to push aside snow or vegetation to access their food.
  • They graze by clipping grasses and plants close to the ground using their wide, powerful tongues and sharp incisor teeth.
  • Bison forage throughout the day, although they are more active during the cooler morning and evening hours.
  • They often form loose social groups while grazing, with vigilant members keeping an eye out for potential predators.

Gathering Food:

  • Bison are known to be migratory grazers, meaning they may move in search of fresh forage as seasons change or in response to changing environmental conditions.
  • Their grazing and trampling behavior can also shape the structure of grasslands, creating a mosaic of different vegetation types that benefit other species.

Bison play a critical role in their ecosystems as grazers and ecosystem engineers, contributing to the maintenance of grasslands and the diversity of plant and animal species in their habitats.


American Bison, commonly known as bison, are remarkable creatures with several unique characteristics that set them apart:

  1. Iconic Symbol of North America: Bison are often considered an iconic symbol of the North American continent. They are deeply ingrained in the cultural and historical identity of the region and are often referred to as “American buffalo,” even though they are not true buffalo.
  2. Massive Size: Bison are one of the largest terrestrial mammals in North America. They have massive, humpbacked bodies, with adult males (bulls) weighing up to 2,000 pounds (900 kg) or more and standing about 6.5 feet (2 meters) tall at the shoulder. Their sheer size commands attention.
  3. Distinctive Appearance: Bison have a distinctive appearance characterized by a large head, a pronounced shoulder hump covered in thick fur, a shaggy mane, and curved horns on both males and females. Their coats vary in color from dark brown to reddish-brown.
  4. Ecosystem Engineers: Bison play a crucial role in shaping their ecosystems. Their grazing and trampling behavior can influence the composition and structure of grasslands, creating diverse habitats for other wildlife species.
  5. Survivors of Near Extinction: Bison are a conservation success story. In the 19th century, they faced near-extinction due to overhunting and habitat loss. Conservation efforts and the establishment of protected areas have allowed their populations to recover, making them a symbol of conservation success.
  6. Strong Swimmers: Bison are strong swimmers and are known to cross rivers and streams during migrations. They use their buoyant bodies to navigate waterways, making them adaptable to various habitats.
  7. Social Structure: Bison exhibit complex social structures within their herds. They form family groups of females (cows) and their calves, often led by a dominant cow. Bulls may form bachelor groups or solitary individuals.
  8. Migratory Grazers: Bison are migratory grazers, moving in search of fresh forage as seasons change. This behavior allows them to adapt to fluctuating food availability and helps maintain grassland ecosystems.
  9. Cultural Significance: Bison have deep cultural and spiritual significance for many Indigenous peoples of North America, who have long relied on them for food, clothing, and cultural practices.
  10. Conservation Symbol: Bison serve as a symbol of the importance of conservation efforts in preserving native species and restoring ecosystems, highlighting the resilience of these magnificent animals.


1. What are the differences between a bison and a buffalo?

The terms “bison” and “buffalo” are often used interchangeably, but they refer to different animals. Here are the primary differences between bison and buffalo:

  1. Species:
    • Bison: “Bison” specifically refers to the two species found in North America, the American Bison (Bison bison) and the European Bison (Bison bonasus). The American Bison is commonly known as the plains bison or buffalo.
    • Buffalo: “Buffalo” is a more general term and can refer to several species, including the African buffalo (Syncerus caffer), the Asian water buffalo (Bubalus bubalis), and the Cape buffalo (Syncerus caffer caffer). These species are not closely related to American Bison.
  2. Geographical Range:
    • Bison: Bison are primarily found in North America, with the American Bison inhabiting regions of the United States and Canada.
    • Buffalo: Buffalo species are found in various parts of the world, including Africa, Asia, and occasionally Europe.
  3. Physical Characteristics:
    • Bison: American Bison have a hump on their shoulders and a massive, stocky build. Their fur is typically dark brown to reddish-brown, and they have a pronounced mane on their neck.
    • Buffalo: African buffalo, for example, are larger and heavier than American Bison. They have a different physical appearance with curved horns that meet at the top of the head and a more bovine-like body shape.
  4. Horns:
    • Bison: Both male and female American Bison have horns that curve upward and do not meet at the top of the head.
    • Buffalo: Buffalo species often have horns that curve outward and then upward, forming a distinctive “V” shape. In some buffalo species, both males and females have horns.
  5. Behavior and Habitat:
    • Bison: American Bison are adapted to the grasslands and prairies of North America and are migratory grazers, moving in search of fresh forage.
    • Buffalo: Buffalo species have diverse habitats and behaviors depending on their region. For example, African buffalo are found in savannas and are known for their social behavior.

In summary, while “bison” is a specific term referring to the American Bison in North America, “buffalo” is a more general term used for various species found in different parts of the world. So, it’s more accurate to call American Bison “bison” rather than “buffalo.”

Related Family Species

  • Britannica, Bison, https://www.britannica.com/animal/bison, retrieved January 2024.
  • Burnie, David & Wilson, Don, Animal, Smithsonian Institute, Washington DC.
  • Clutton-Brock, Juliet and Wilson, Don, Mammals, Smithsonian Handbooks, New York, NY.
  • Hickman et al, Integrated Principle of Zoology, McGraw Hill, Boston.