American bison characteristics, habitat, feeding

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Basil Manning

The American bison (Bison bison) is a placental mammal that is part of the Bovidae family. This ungulate is characterized by having a hump on the front dorsal part and a large head, in relation to the dimensions of its body. In addition, the hindquarters are much thinner than the front.

Their fur varies according to the seasons. In the winter it is long, thick and dark brown in color, while in the summer it is short and light brown. In a very particular way, the head of the American bison is densely populated with hairs. This is an adaptation to the low winter temperatures, since the thick layer protects the head from the strong winds, typical of the regions where it lives..

American bison. Source: Photo by David J. Stang [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)]

Previously, the Bison bison it was distributed from the Gulf of Mexico to Alaska. However, in the 19th century it was very close to extinction. This was due to poaching and diseases introduced by domestic livestock..

At present, its population is reduced to the reserves and national parks located in Canada and the western United States..

Its habitat is very varied, and can be found both in semi-desert areas and in areas covered completely with snow, as occurs in Alberta, a province of Canada..

Article index

  • 1 Features
    • 1.1 Fur
    • 1.2 Size
    • 1.3 Head
    • 1.4 Communication
  • 2 Habitat and distribution
    • 2.1 Distribution
    • 2.2 Habitat
  • 3 Conservation status
  • 4 Food
    • 4.1 Digestive system
  • 5 Playback
  • 6 Behavior
  • 7 References

Characteristics

Fur

The young of this species exhibit, until the second month of life, a paler coloration than that of the mature bison. In the adult, the front parts of the body, which include the neck, head and forelimbs, have a thick layer of long dark hairs. As for the back, it is covered in shorter fur.

The difference between the length of the hair is more noticeable in males. In addition, this one has a black beard approximately 30 centimeters long.

An American bison has a long, very dense, dark brown winter coat. The head is the structure that has the most hairs. This adaptation allows it to withstand the strong and cold blizzards that occur in its habitat during winter.

This thick winter coat gradually falls off during the spring. So, in the summer, the mammal sports a lighter coat and a lighter shade of brown..

Size

One of the characteristics of ungulates is that males are larger than females. Thus, the male American bison is about 1.9 meters high up to the hump and its body varies between 3.6 and 3.8 meters in length. Regarding the weight, it is from 480 to 1,000 kilograms.

In relation to the female, the height up to the shoulder ranges from 1.52 to 1.57 and the length measures between 2.13 and 3.18 meters. Their body mass ranges from 360 to 544 kilograms.

Head

The head is large compared to the dimensions of the body. Both sexes have horns, which can grow up to 24 inches. These are black, short, and curve outward and then upward, ending in a pointed end.

Communication

The American bison has an excellent sense of smell, which it uses primarily to detect danger. In addition, this ungulate has the ability to distinguish large objects that are a kilometer away..

If it is an animal in movement, you could visualize it, even if it is two kilometers from it.

To communicate, you can use chemical signals, especially in the reproductive stage. In addition, the Bison bison emits vocalizations, such as snorts, used to warn the group of an intruder.

Also, it produces sounds similar to grunts, which are used to maintain contact between members of the pack..

Males show their dominance by hitting the head with that of other males. In addition, they can kick the ground defiantly or bellow in a hoarse tone, but they rarely fight to the death of the opponent..

Wild American bison from Yellowstone can be seen in the following video:

Habitat and distribution

Distribution

In times past, the Bison bison they had the widest distribution of any herbivore in North America. This species was found from the arid grasslands of Chihuahua, in Mexico, crossed the Great Plains of Canada and the United States, until reaching the riparian meadows, in Alaska.

Subspecies B. b. bison lived from northern Mexico to central Alberta. Regarding the B. b. athabascae, ranged from central Alberta (Canada) to Alaska in the United States.

The great slaughters of these ungulates caused their extermination, in most of their natural habitat. The current range is restricted by land use, disease, and wildlife management policies. This has resulted in the American bison currently occupying less than 1.2% of the original range..

Today, this species is found in private and protected territories in the western United States and Canada. Among these protected areas are the Forest Buffalo National Park, located north of Alberta and south of the Northwest Territories, Canada. In the United States is Yellowstone National Park, in Wyoming.

Habitat

Historically, the Bison bison it lived in the open savannas, wooded areas, and grasslands of North America. Also, they were found from semi-desert to boreal habitats, if the foraging was adequate. At present, it is located in fragmented populations, occupying a wide range of elevation.

Thus, it can inhabit arid regions, such as those that exist in New Mexico, and in areas with a snow cover, as occurs in Yellowstone National Park..

Among the preferred habitats are river valleys, grasslands, plains, scrublands, semi-arid regions, and semi-open or open grasslands. Also, this ungulate tends to graze in mountainous areas, with little steep slopes..

State of conservation

During the 19th century the indiscriminate hunting of the American bison caused the near extermination of their populations. Due to this situation, the IUCN included this species within the group of animals in danger of becoming extinct..

Among the threats that afflict it are the degradation and loss of its habitat, hybridization between subspecies, introgression with livestock and the infection of diseases transmitted by livestock. In this sense, some populations are killed to prevent the spread of brucellosis and bovine tuberculosis.

With regard to conservation actions, since 1960, a recovery program has been carried out in Canada. In these, the National and State Parks and the refuges play an important role in the maintenance of the herds.

Within the planning, is the restoration of populations located in southern Colorado, Alberta, northern Montana and Arizona. In addition, recently reintroductions of the Bison bison in Yukon.

On the other hand, the American bison is listed in Appendix I of CITES and Bison bison athabascae it is in Appendix II. In addition, this subspecies is listed in danger of extinction, by the Endangered Species Act of the United States.

Feeding

The Bison bison it is a herbivore that ingests about 1.6% of its body mass daily. Its diet is mainly based on grasses, but when these are scarce, it eats a wide variety of plant species..

Thus, the diet in autumn and summer includes flowering plants, lichens and leaves of woody plants. Also, it tends to consume the roots and bark of shrubs..

During the winter, the American bison digs the snow, to find its food. For this, it moves its head from side to side, which makes its muzzle clear the ice from the ground..

Digestive system

This species is a ruminant that has a stomach with four chambers: rumen, reticulum, omasum, and abomasum. This adaptation facilitates the degradation of cellulose, which forms the walls of plant cells. In addition, it helps in the digestion of fibers, typical of woody plants.

The rumen and the reticulum contain microorganisms, which are responsible for carrying out a first fermentation process. In this, the initial organic components are transformed into assimilable substances.

In the omasum, fibrous materials that have not been digested are retained and subjected to various digestive processes. Also, this cavity has a high absorption capacity, which facilitates the recycling of water and minerals..

The last compartment is the abomasum, which functions like the true stomach. Thus, in this structure, enzymes act to break down the proteins in food. In addition, a large part of the nutrients are absorbed in said cavity..

Reproduction

The female is sexually mature at 2 or 3 years old, while the male mates when he is 3 years old. However, it does not reproduce until they reach 6 years of age, when they are the appropriate size that allows them to compete with other males for access to females..

Regarding the mating season, it occurs from the end of June to September. During this time, the dominant males have a small harem of females, with whom they will copulate during the first weeks. As for subordinate males, they will mate with any female that has not mated.

Gestation lasts about 285 days. The pregnant female will give birth to a single calf, weighing between 15 and 25 kilograms. It is born in a secluded place from the herd and after several days, the young can follow the herd and its mother. The calves are suckled for 7 to 8 months, but by the end of the first year they already eat herbs and grasses. Here you can see how a female gives birth to a young:

The care and protection of the young is fundamentally in charge of the mother, an action that is carried out during the first year of the young person's life. In the following video you can see American bison in mating season:

Behaviour

During the fall and winter season, the American bison tends to gather in more wooded areas. In these seasons, this ungulate exhibits a very particular behavior with its horns. This consists of rubbing them against the trees, the preferred ones being pine and cedar.

This behavior could be associated with defense against insects, since it is carried out at the stage when the invertebrate population is highest. Thus, the aroma of cedar and pine trunks is impregnated in the horns, serving as a deterrent for insects..

Other behavior that characterizes the Bison bison It is to wallow in shallow depressions of the ground, whether they are dry or wet. The mammal rolls in these spaces, covering its body with mud and dust.

Experts put forward several hypotheses that try to explain the purpose of this behavior. These include grooming, associated with shedding, playing, eliminating ectoparasites and relieving irritation caused by insect bites..

References

  1. Wikipedia (2019). American bison. Recovered from en.wikipedia.org.
  2. Newell, T., A. Sorin (2003). Bison bison. Animal Diversity Web. Recovered from org.
  3. Aune, K., Jørgensen, D., Gates, C. (2017). Bison bison. The IUCN Red List of Threatened Species 2017. Retrieved from iucnredlist.org
  4. Smithsonian's National Zoo & Conservation Biology Institute (2019). American bison. Recovered from nationalzoo.si.edu/
  5. The National Wildlife Federation (2019). American bison. Recovered from nwf.org.
  6. Murray Feist, M. (2019). Basic Nutrition of Bison. Saskatchewan Agriculture. Recovered from mbfc.s3.amazonaws.com.

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