Bison bison bison
With gracious permission from Joseph
NRDC Bison Fact Sheet
ARE THERE ANY WILD BISON IN OUR
By Jim Bailey, PhD, Retired wildlife biologist, Belgrade, Montana
also avaialable in PDF
Plains Bison Overview
Plains bison are the best-known of three
types of bison. Other bison are the wood bison, of central and
northern Canada and Alaska, and the European bison. We do not
know how many plains bison inhabited North America at the time
of European contact. Estimates are there were at least 30 million.
Most Americans are familiar with the history of bison abundance
and annihilation on the Great Plains. But bison once occurred
in all but a few of the United States. Beginning in the 1670s,
Spanish journals record bison in the panhandle of Florida. The
species occurred from southern New York and the tidewater lands
of Virginia, across Texas and a little of Old Mexico, in southern
Canada and the Rocky Mountains, and in Oregon and California.
However, they appear to have been rare in the arid Great Basin
and Columbia Basin habitats of Nevada, Utah and southern Idaho.
In 1769, Daniel Boone saw thousands of bison in western Kentucky,
and George Washington killed a bison in West Virginia. Perhaps
the latter was one of the King’s bison, since it was before
Bison in Montana
Most of the year, there are no wild bison
in Montana where thousands of the animals once roamed. Each
spring, a limited number of bison are allowed to leave Yellowstone
National Park and visit Montana. Under current government policy,
they must either be eliminated or hazed back into the Park by
May 15. About 350 bison at the National Bison Range, near Moise,
are a penned semi-wild (or semi-domestic?) herd. Montana law
designates them as a “display herd” in an “exhibition
pen”. The American Prairie Reserve, south of Malta, has
about 200 bison. However, these are legally defined as private,
In the United States, Montana has the two
largest, most appropriate areas of mostly public land where
wild plains bison may be restored. One includes Montana’s
portion of the greater Yellowstone area. Currently, bison are
restricted mostly to the high-elevation environment of the Park.
This range, of the wildest plains bison herd remaining in the
USA, should be expanded to include lands at lower elevation
– public lands where wild bison are appropriate and private
lands where bison are welcome. Another area includes the Charles
M. Russell National Wildlife Refuge, the Upper Missouri River
Breaks National Monument, and nearby abundant Bureau of Land
Management land. However, the management plan for the Wildlife
Refuge states that Montana will have to take the first step
in restoring wild bison.
There are about 200,000 privately owned
plains bison in over 4,000 commercial herds in the United States.
In these herds, bison are being domesticated and gradually losing
the characteristics of wildness that we, including the bison
ranchers, prefer. Herds are managed much like other livestock,
with selected culling, skewed sex ratios, forced weaning, vaccinations,
vermicides and antibiotics, limited pastures with forced pasture
rotation, assisted calving, and supplemental feed and water.
Delegating the task of restoring wild bison to commercial producers
is an illusion.
Wildness is the extreme in a continuum
from domestic to wild. However, the benchmark of wildness is
a preponderance of natural selection. Evolution through natural
selection in wild environments gave us wild bison that are alert,
efficient, mobile, agile, strong, enduring and disease-resistant.
Evolution through artificial selection, and the weakening of
natural selection that occurs in small herds, are replacing
these wild characteristics of plains bison today.
Admittedly, natural selection can be brutal.
Animals starve. Many young and the old are killed by predators.
Bull competition for mates results in injuries and even death.
Less resistant bison die or fail to reproduce due to disease.
This is the process of wildness. We may not remove the harshness
without destroying the wildness.
There are 44 conservation herds of plains
bison on native range in the USA. These are herds managed by
government agencies or owned by the Nature Conservancy or the
American Prairie Reserve. The 44 herds have about 17,000 bison.
Thirty-eight of these herds have no more than 500 bison and
only 4 have more than 1000. Thirty-nine of these herds reside
within fences and 1 is on a large island. Almost all these herds
are managed with at least some practices commonly used within
commercial herds of bison, leading to domestication. Even the
Yellowstone Park herd suffers some practices leading toward
Plains bison barely escaped extinction
in the late 1800s within Yellowstone National Park and in a
few, small private herds where they were crossbred with cattle.
Today, cattle genes occur in almost all the remaining bison.
There may be only 4 sources of bison without cattle gene introgression
– in Yellowstone, in the Henry Mountains of Utah, in Canada,
and in a private herd in New Mexico. Herds with high levels
of cattle genes have limited value in bison restoration. Herds
with low levels of cattle introgression might be purged of undesirable
genes if they can be subjected to natural selection in a wild
Small bison herds, less than 400-500 animals,
will become inbred. Inbreeding results in poor reproduction,
lowered resistance to disease, and other undesirable traits.
Twenty-one of our 44 conservation herds in the USA have no more
than 120 bison. Inbreeding is certain in these herds.
Genetic diversity is necessary for a population
to continue to evolve and adapt to its environment. A bison
herd of 2000-3000 animals will lose an estimated 5% of its genetic
diversity during every 100 years. Smaller herds will lose even
more of their genetic diversity. The process is called genetic
drift. It is due to random events that occur during production
of ova and sperm, and during the lifetime of each bison cohort.
The first 100 years, and more, of this genetic loss in bison
are behind us. No plains bison herd had even 1000 animals during
most of this time. Today, only 4 conservation herds in the USA
exceed 1000 bison and only 2 exceed 2000 bison. Genetic diversity
of plains bison is being diminished with every generation of
We do not leave bison to future generations
of Americans. Bison die. We leave the bison genome to future
generations. We will not fulfill our obligation to the future
until we have at least a few large herds of wild bison on large,
diverse natural landscapes where natural selection may determine
the bison genome.
Brucella abortus is a bacterium causing
the disease brucellosis. Brucella came early from Europe to
North America, probably with Spanish cattle. The disease may
occur in several species, but today it is best known in elk,
bison and livestock. It causes abortions, mostly with an animal’s
first pregnancy, and may cause weight loss. In humans, the disease
is called undulant fever, which was a serious issue before milk
was widely pasteurized. The threat of economic losses due to
brucellosis is still a serious issue for livestock producers.
Mostly, Brucella are transmitted between animals when uninfected
animals lick an infected aborted fetus or placenta. There is
no clear evidence that bison have transmitted Brucella to cattle
in wild conditions, though it is likely that this may occur.
All recent occurrences of brucellosis in livestock surrounding
Yellowstone Park have occurred in herds exposed to elk. Most
Brucella-caused abortions occur during February and early May.
However, most fetuses and placentas are removed quickly by scavenging
animals and the bacteria do not persist in the environment,
especially as the weather warms. The risk of live bacteria in
the environment is near zero by June 15.
In wild environments, wildlife naturally
coevolve with their pathogens. Host wildlife become more resistant
to diseases and pathogens become less virulent. This process
is especially appropriate in Yellowstone National Park which
has a mandate to leave Park resources, including natural processes,
unimpaired for future generations. Already, brucellosis is not
considered a debilitating issue for Park elk or bison populations.
Since Brucella is widespread in elk and other wildlife and there
is no conceivable possibility of eliminating it from the Park,
it is a naturalized species that should coevolve in the Park
ecosystem. Misguided attempts to manage brucellosis in Park
wildlife will interfere with this coevolution and could have
unknown impacts on other host-pathogen relationships. The primary
place for managing livestock diseases is in livestock management,
not in wildlife management.
For the above reasons, Gallatin Wildlife
Association opposes vaccination of Park bison or selective slaughtering
of bison that test positive for having been exposed to the disease.
Those testing positive may be carrying active infections, or
they may have recovered from the disease and may be the individuals
most resistant to Brucella. We also oppose capturing bison and
placing them in crowded pens with artificial feed - as a means
to limit the number of bison leaving the Park. This unnatural
process exposes bison to increased risks of disease transmission
for any of the pathogens they may carry.
Let’s face it, bison are not like
other big game. They are large. They go about in large herds
in open terrain. One former Montana governor has described bison
hunting as akin to shooting a couch. Bison force us to rethink
the meaning and intent of the terms “hunt”, and
“fair chase”. Perhaps “harvest” is a
more truthful term. That “hunting” and “chasing”
may be minimized in bison harvesting within some environments
does not mean that harvesting a bison is valueless.
In the Yellowstone area, bison are habituated
to people and have not learned to fear hunters. In contrast,
annually hunted bison in the Henry Mountains of Utah are often
hard to find and difficult to approach. The behavior of bison
in relation to hunting will depend upon their experience and
upon the size and topographic and vegetative diversity of their
We deplore commercial bison hunting in
a pen. If bison are free-ranging within a large and diverse
area, a bison hunt will require planning, probably some stalking,
careful selection of the sex and age of the quarry, good shot
placement, and the effort, cooperation and camaraderie of friends
or family to process the large and valuable carcass. These enhance
the hunting experience.
Restoring wild bison will require some
large herds on large, diverse and wild ranges. There will be
little gained by establishing any new herd of less than 1000
bison on less than 100 square miles. We already have such conservation
herds. In these herds, managing the numbers of bison and limiting
their distribution results in loss of genetic diversity and
domestication of the species. Larger, more mobile, less intensively
managed herds are needed to assure wildness of plains bison.
In the Yellowstone area, we only need to
allow some bison to live on ancestral range outside the Park.
Much of this land has no cattle, so brucellosis is not an issue.
There is public land and private land where bison are wanted.
Bison can be fenced out of private land where they are not wanted.
This is already happening. Other land has cattle only after
June 15 when the risk of Brucella transmission from bison is
near zero. Intensive management of cattle to control the risk
of brucellosis is already necessary in this landscape where
elk carry Brucella. Managed public and tribal hunting can be
used to control both numbers and distribution of bison on this
landscape. Public hunting should be used as a tool of wildlife
management, not of wildlife annihilation.
Lead the Nation
History has given Montana the opportunity
to lead in restoring wild plains bison – in the Yellowstone
area and surrounding the C. M. Russell National Wildlife Refuge.
Some would say this is not an opportunity, but an obligation.
Will Montana lead in dealing with the issues and solving the
problems, or drop the ball?
Bison Myths PDF
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