The Wood Bison is
the larger subspecies of the American Bison, with the other one being its
southern cousin – the plains bison. This beast,
in fact, is the largest of North America’s land mammals, as also, all
theterrestrial living animals. However, presently, the population of these
historic animals is decreasing at a rapid rate. As of May 2013, the population
of the wood bison in Canada is approximately 11,000.
Table of Contents
Scientific Classification
Animalia
Chordata
Mammalia
Artiodactyla
Bovidae
Bison
B. bison
Bison bisonathabascae
Table Of Content
Table of Contents
Scientific Classification
Animalia
Chordata
Mammalia
Artiodactyla
Bovidae
Bison
B. bison
Bison bisonathabascae
Table of Contents
Physical Description/Characteristics
Size: The range length of the wood bison is 3.04 – 3.8 m, excluding the tail, and a height of around 1.67 – 1.82m at the shoulder.
Weight:They can
weigh anything between 350 and 1000 kg.
Bodily Features: A
huge, wide head and a large shoulder hump close to its front legs. The
shoulders and forelimbs are covered with
shaggy golden to dark brown fur.The hindquarters are somewhat shorter than the
front ones.
Tail: They have a
distinctive short, tasseled tail, with a small tuft of dark hair at the tip.
Horns: Both the
sexes have short black horns.
Sexual Dimorphism: Not visually present, except that the males are around a foot larger than
the females.
Wood Bison vs. Plains Bison:The Differences
There are quite a few visual differences between the two
subspecies:
Compared to the plains bison, the wood bison is larger and heavier, attaining a weight of almost 200 pounds more.
The hump of the plains bison is rounded, while the wood bison’s is somewhat squared.
The wood bison is darker in color than the plains bison.
The facial beard, the hairs in the throat latch, ventral neck mane, chaps, and penis tuft of the wood bison are smaller and more pointed, whereas the plains bison’s hairs are larger and rounded.
Lifespan
Wood bison can live for 18-22 years in the wild andmore than 30 years in the zoo/captivity.
Distribution
This subspecies is native to North America and is distributed
throughout the western Northwest Territories, Alaska, Yukon, northeastern
British Columbia, northwestern Saskatchewan, and northern Alberta.
Habitat: Where do Wood BisonLive
The wood bison are found
in a wide variety of habitats including meadows along riverbanks, boreal
forests, muskeg swamps, and scrub-land. As the spring and summer arrive, they
begin foraging in the relatively drier, grassy meadows, parklands, andshrubby
savannahs. During winter, they shift to the wet meadows, as well as in the lake
areas, when they freeze.
Behavior
Wood bison are social animals that live in herds and are
found roaming in small groups all throughoutthe
year. The herds primarily comprise of adult females, sub-adults,and calves. It is their social norm to mingle
with the bulls only during the mating season.
Because they are primarily ruminants, they spend a long time
every day chewing their cud, and hence, are seen spending less time grazing in meadows.
The mood swings of these
animals can easily be understood from the movement of their tails. When the
tail hangs downward and switches naturally, it means, the beast is in a calm
temperament, but if standing upright, accompanied by bellow sound/calls, it may
be ready to charge.
These animals are very protective of the members of their group. Not only that, they would also maintain a hierarchy, with the leader usually
taking various decisions. The males that have passed three years of age are
subjected to leave the herd, and instead, form bachelor herds.
Diet
These bison are completely herbivorous beasts. 85% of the
diet of the bison is made up of sedges and grasses, while the remaining 15%
consists of herbs, some shrubs, lichen, and willow leaves.
Mating and Reproduction
The mating season of the wood bison falls between July and
early September. The females of the species generally give birth to its first calf at the age of three years. In the case
of the males, strong competition bars the young animals to defeat the larger
and mature bulls to win over a mate.
At times, such combats lead to serious injuries, and if the
challenged male is not intended to fight, it walks away from the competitor
male. Hence, the former need to wait until they are around seven to eight years
old and get stronger to defeat the others.
These beasts are usually polygamous
and indulge in copulating with more than one female. With the arrival of the breeding
season, the dominant male bison maintain and protect a harem of female bison until
they are sexually ready for mating.
Life Cycle
The female bison generally gives birth to one calf at a
time, and a total of two calves in a three-year
period. The offspring are born in around May after a gestation period of
about 277-293 days.
When a female is about to give birth, it leaves the herdand rejoins only after the baby is born,
and is able to run. This takes about three hours from the birth of
the young.
The juvenile begins
spending time with the members of the herd
and gradually gain strength with the care and cooperation of the entire group.
Very soon, it becomes ready to run with its herd members by autumn.
Interestingly, the individuals that are born earlier tend to mature faster with the advent
of autumn and become more dominant when
they grow up to adults.
The young bison are weanedwhen
they are seven monthsold and are nursed for up to a year. They remain with
their mothers for three years, by which time they attain the age of sexual
maturity. The female juveniles attain complete physical maturity at the age of
three years, and males at six years.
Adaptations
They have extremely strong
horns and powerful hooves, so much so, that, getting a chance, they can
often invade carnivorous predators.
The rate of metabolism in
these animal decreases with the fall in temperatures. Hence, they are adapted to living on a very limited amount of food during the
winter months.
As a behavioral
adaptation, the wood bison are highly alert and suspicious in nature, and a mere cracking of a
branch, or just the sound of a footstep,can result in the entire group
leaving the area.
Predators
By virtue of their
large size and immense strength, healthy adults are practically safe from
predators. However, injured/sick/young individuals can fall prey to predators
like mountain lions, wolves, and even humans.
Conservation Status
Considering their decreasing population, the IUCN 3.1 has
marked them as a ‘NT’ (Near Threatened)
species.
Interesting Facts
Apart from hunting,
diseases, including tuberculosis, brucellosis, etc., have always played a
vital role in the degradation of their population, killing very large
numbers of these animals in a short time
period.
Though it is often mistakenly termed as ‘buffalo’, but
scientifically, it is considered as a misnomer, since it is only a distant
relative of the two ‘true buffalo’ species – the Asian water buffalo and
the African buffalo.
Yellowstone National Park
is the only place in the U.S. where these
bisonhave continuously been living since prehistoric times.
Because of their reddish
body tinge, the baby bison have earned the nickname ‘red dogs’.
The wood bison is the
official ‘National Mammal’ of the United States.