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The American bison is commonly known as "buffalo" and I
will use the terms interchangeably on this site. Strictly speaking,
however, the word "buffalo" refers to the Southeast Asian animal, such as
the water buffalo, or the African cape buffalo. The true buffalo has
thirteen sets of ribs, whereas the American bison has fourteen sets. The
American bison is the largest of all native North American land mammals,
including the moose and Kodiak bear.
The ancestors of the American bison are:
- Bison priscus - steppe wisent of Europe and Siberia hunted by
Cro-Magnon man, a huge animal
- Bison latifrons - half larger than our modern bison with horns
spanning 7-9 feet
- Bison antiquus - an animal hunted by Folsom man about 10,000
years ago
- Bison occidentalis - a large plains bison
- Bos bison - our modern day bison
- The bison has been reclassified from the genus Bison
into the genus Bos, which includes all ungulates and wild cattle.
It is estimated that the population of bison in the United
States when Columbus landed was 30-60 million. They have been hunted for
more than 12,000 years. The early European explorers and settlers hunted
the bison for the same reason that the Native Americans did, except that the
Native Americans used all parts of the bison for meat, clothing, shelter,
and tools, whereas the white hunters used only the delicacies like the
tongue, and left the rest of the carcass to rot. Such was the misfortune of
having an overabundance. When the railroads were built in the west the
train crews and passengers killed the bison only for "sport." And so
dwindled the herds of these wild animals.
In 1888 there were only 541 bison remaining in the United
States. William Temple Hornday, an American zoologist, was determined to
protect and increase the small herds. A census in 1907 indicated that some
success was evident as there were 835 wild bison and 256 bison in captivity.
Sanctuaries, zoos, and parks proved to be safe havens for them. The first
national preserve for bison was founded in 1907 near Cache, Oklahoma and
later became the Wichita Mountains National Wildlife Reserve. Game laws
also help to save the American bison from extinction. It is estimated that
there are at least 250,000 bison in the United States.
Bison Facts
Bison bulls weigh 1,600 to 2,000 pounds and stand 5.5 to
6.5 feet at the shoulder. They measure 9.5 to 11.5 feet in total length
(including the tail). Bison usually live no longer than 20 years, but some
have been known to live as long as 40 years. The cow is smaller, weighing
up to 1,100 pounds. It is 4.5 to 5.5 feet high and less than 10 feet in
length. The cow has a smaller hump than the bull and her horns are more
slender and curved than the bull.
Bison are definitely social animals and live in herds,
although it is not unusual to see an occasional single animal on the
prairie. The loners are often older bulls. The size of the herds vary
during the year. In the winter the herds are much smaller, typically 20 to
30 in number. During the rut (mating season) the bison gather in large
numbers. The bison social order is definitely matriarchal with the cows
leading the herd movement. Bison move over the prairie as they graze,
more so than cattle.
During the winter the bison's coat is at its thickest,
which protects it from the cold wind and snow. In the spring the coat falls
off in clumps. Often the animal will rub against something to promote loss
of excess fur. Although the coat appears to be stiff and wiry it is
actually quite soft. The coat is thickest from the hump to the shoulders,
which makes the hump appear to be taller than it really is. The hair on
older animals have been known to grow to 22 inches in length. Various
critters that live on the prairie welcome the shedding of the bison coat.
They use it for prime nesting material in the spring. Birds and rodents
are particularly fond of the fur.
The rutting season is usually from mid-June to September.
Heifers typically breed at two years of age and calve at three years. The
gestation period is 9.5 months. The 30-40-pound calves are born in late
March to May. Cows produce one calf a year for about 15 to 20 years. Twins
are very rare. The new calves are an orange-brown color, much lighter than
its mother. The calves play and romp with their young friends, but they do
not stray very far from their mother.
Bison Behavior
Bison are grazers and they walk while biting off mouthfuls
of grass. The grass is quickly swallowed to be later brought up for
cud-chewing later in the day and at night. Their diet is 99+ % grasses as
opposed to forbs. They can go a long time without water and travel long
distances to find water. An adult will consume more than 30 pounds of
grass (dry weight) in a day. Unlike cattle, they do not have to be fed
supplementally during the winter.
Bison, especially the large bulls, look very slow and
clumsy. In fact, they can run up to 35 miles per hour. They can also jump
6 feet high (vertically) and 7 feet horizontally. Bison are powerful
swimmers.
Bulls and cows at all ages will wallow in dry areas where
they can stir clouds of dust. Sometimes they will wallow in wet areas as
well. Dust, which permeates the coat, probably minimizes the effects of
insects. The wallowing seems to be important in grooming, sensory
stimulation, alleviating skin irritation, and reproductive behavior.
Wallowing also transports soils and seeds to other areas of the prairie.
The wallows also serve a purpose in the prairie ecosystem. They collect
rain water and form small ponds which become available to vertebrates
and invertebrates. The supply of water enhances the growth of specific
vegetation needing a moist or wet habitat, such as rushes.
Bison have a keen sense of smell, but their eyesight is
poor. They contact one another by uttering grunts. They are normally
mild mannered, but they can be unexpectedly aggressive. Threat postures
include a snort or guttural bellow with head up, mouth open, and tail erect.
Tallgrass Prairie
Preserve
The Tallgrass Prairie Preserve in northeastern Oklahoma
is owned and managed by The Nature Conservancy. It consists of about 39,700
acres of beautiful prairie. The Nature Conservancy (TNC) bought a portion
of the Chapman-Barnard Ranch and had the objective of not only preserving
the grass prairie, but to restore to its original prairie ecosystem.
To do this TNC uses grazing animals (bison) and controlled burns. This will
keep the trees and brush from overtaking the grass prairie and will increase
the biodiversity of plant life. Each year about one third of the prairie is burned
to remove dead biomass and trees.
In 1993 a herd of 300 bison was donated to the TNC and
they were introduced, with much publicity, to the Tallgrass Prairie
Preserve. Today the herd has grown to over 2000 bison. Each November the
bison are rounded up and given their shots to prevent diseases. Each has
a computer chip in its ear which affords a way to keep a large amount of
information on the bison. A record is kept on each animal giving a history
of where it came from, weight changes, etc. At this time the new calves
are given their identification chips. It is important to keep a record of
their genetic history to prevent excess inbreeding of the herd. Each year about 600
calves are born. After the roundup about 600 bison are sold, which affords income and
returns the heard to about 2000 for the winter.
The cows start to have their calves in late March. The young are
orangey in color and about 40 pounds when born. It is quite a wonderful
sight to see a herd of 2000 adult bison and hundreds of frisky calves
romping over the rolling hills of the prairie.
Bison Wallows
Bison wallows, also known as buffalo wallows, are found
wherever there are bison groups. The average size for these holes is about 15 feet wide and 1 foot deep. Typically wallows are found in prairie areas that are sandy or dusty, but wet wallows are also found. It is no doubt that bison enjoy the act of wallowing, but it is necessary for the good health of the animal. It provides the animals a way to protect themselves from biting insects by coating their fur with dust and in the case of wet wallows, with mud. Wallowing helps the bison detach it's winter coat of fur in the spring when the weather turns warm. It is not uncommon for the bison to enrich the wallow dust with it's urine or dung, which makes the fight against the insects more effective. Wallowing, especially, in a wet wallow may help reduce the animal's body temperature.
The bison wallow also seems to have a social aspect about it. It is not uncommon for
for one animal to displace in the wallow an animal of a lower rank. Bulls, when feeling threatened will urinate in a wallow then roll in the dampened dust. Does this send a message to the "enemy?" Bison cows rarely do this.
Wildlife benefits from the wallows also. Insects, rodents, and small animals find a haven in these shallow holes. When muddy or wet they can burrow into the earth and create places of refuge or nests in which to breed and raise their offspring.
Wallowing usually follows a pattern of behaviour. There is usually preliminary sniffing of the ground, pawing and horning the ground and finally rolling in the dust. The animal lies down and starts to kick its legs so as to roll on one side. An adult bison does not roll over completelly because of the large hump on its shoulder. Bulls tend to wallow more frequently than cows. As bison travel across the prairie their
fur picks up seeds, which get deposited in the wallows. When rain water is collected the seeds sprout.
When a bison wallows it compacts the soil which forms a perfect basin for collecting rain water. There are written memoirs of some early settlers that state that the water collected in bison wallows was life saving when the wagon trains ran out of water while crossing the prairie. The pools of water collected in wallows were used as swimholes by the tired, dusty, and hot cowboys. Care had to be taken when using the water for drinking,
as these pools could become stagnant and cause sickness. Wallows were not always a welcome sight. The early farmers considered wallows to be a bane of existence since the soil was packed and hard, making plowing difficult.
Very old wallows are still observable, especially from aircraft, because the type of grasses and plants that grow in
these indentations are usually different from the surrounding plant life and have a different color and texture.
Rushes and sedges, plants that require a moist soil, often grow in wallows and they are often a darker green color than the surrounding grasses.
Alice Outwater, an environmental engineer, contends that when there were 60 million bison on the prairies of this
country, there were very many wallows. When they collected rainwater they prevented quick runoff and allowed the water to penetrate the earth and
enter the aquafers. She feels that the bison, along with the bevers and prairie dogs, were the first important purifiers of the nation's water
supply.
Bison Photos
 Bison on June 27
 Spring is Here!
 Scratching Post!
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