Bison group on the move at sunrise in Lamar Valley. NPS / Jacob W. Frank In the coming months, Yellowstone National Park, as part of the Interagency Bison Management Plan adopted with the state of Montana in 2000, intends to reduce the current size of the park's bison herd from around 4,800 to between 3,900 and 4,200.

Last winter 1,200 bison were removed—the largest reduction in a decade—with more than half sent to slaughter and nearly 500 killed by hunters. Nine of every ten Yellowstone bison that died were killed beyond the park's northern border in the Upper Yellowstone River Valley. The goal, park officials say, is to eventually reduce the number of bison to between 3,000 and 3,500.

Since the mid 1980s, more than 10,400 of the Yellowstone icons have been killed for wandering into Montana based on the now-debunked premise that they represent imminent threats of passing the disease brucellosis to domestic cattle. Critics say the "hunting" of park bison is anything but a sporting proposition; most animals are accustomed to people and do not flee.

The question is not only why more bison continue to be slaughtered or placed in quarantine, but also what are the consequences of removing animals that are merely acting upon ancient biological instincts to escape deep snow at higher elevations and move to lower-lying grasslands outside the park?

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To be clear, the following parallel drawn between bison and elk is not intended to be a blanket anti-hunting statement. However, it has been asserted by government wildlife officials I’ve spoken with that when hunters opened fire on elk migrating out of Yellowstone across its northern border into Montana this fall, and for those who formed a firing line shooting at elk sprinting for their lives across Grand Teton National Park, there was no sophisticated selection or discrimination going on related to which animals were being felled.

Quite the opposite.

During those years in the late 1980s and 1990s when the state of Montana conducted its elk reduction near Gardiner, Montana to dramatically reduce the number of wapiti on Yellowstone's northern range, late season elk hunts were held in which pregnant cow elk were killed. Thousands of elk were eliminated and veteran sportsmen I knew called the scene the antithesis of ethical hunting.

People forget—especially those who hate wolves—that before wolves were restored in the mid 1990s, many of those same individuals lobbed a fusillade of criticisms at Yellowstone, claiming the park was mismanaged and the northern range grossly overgrazed by 19,000 elk.

Moreover, they either forget or deny that wolves, in reducing elk numbers, have produced a number of ecological dividends . Though there is widespread dispute over whether there has been a full-blown “trophic cascade effect”, having fewer elk has dramatically changed the way the landscape is being used.





The number of wapiti on Yellowstone's northern range today is closer to 6,000 which move seamless in and out of the park, and there are actually far fewer wolves in the park now than a decade ago. In recent years, bison have become more numerous. Some now claim, including Yellowstone, that the park’s northern rangelands hold too many bison .

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While wolves have received much of the blame for fewer elk, no intense analysis has ever been done on the ripple effects caused by humans, poised along the park border in Montana, killing so many female elk of prime reproductive age; no analysis has been done on what the removal of big elk bulls has meant to the gene pool or even what effect those factors had on leaving elk in a better position—or worse—in being able to fend off predation by wolves.

Bison herd with calves in Lamar Valley; NPS / Neal Herbert

Similarly, it's reasonable to ask, what effect has the indiscriminate, non-selective slaughter of more than 10,000 Yellowstone bison wandering into Montana, killed under the dubious premise that they represent an ominous risk of brucellosis transmission to private cattle herds, had on the health of the park’s bison herd? As many wonder aloud, how have the killing fields in Montana, along both the park's northern and western boundaries, affected the social dynamics of Yellowstone’s bison?

Bison moving out of the park carry with them an age-old, deeply-engrained instinct—to migrate. What does it mean to continuously remove those animals which are only following their evolutionary drive to leave higher elevation areas inundated by heavy snows in winter, seeking instead better places to feed on grass at lower elevations? How has snuffing out this instinct, by slaughtering bison in mass, contributed to the current problem of so many bison now congregated on Yellowstone’s northern range and causing some perceived overgrazing problems?

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Yellowstone today finds itself boxed-in by the state of Montana. Yellowstone officials have said that in order to preserve the ecological and genetic integrity of park bison a minimum of between 3,000 and 3,500 needs to be maintained across decades. Yellowstone and its mountain setting, however, is actually not a place where bison would naturally choose of their own accord to congregate.





Many of Yellowstone's bison are descended from just 26 wild survivors that found refuge in the park during the late 19th century when a species that once numbered between 30 million and 60 million was reduced to mere hundreds. Yellowstone became a safe harbor because of its geographic remoteness. Survivors of near extinction—the equivalent of a biological holocaust perpetuated on them—conservationists and indigenous people argue that Yellowstone's bison herds deserve to therefore be treated with special, almost sacred, status.



Yellowstone northern range has been compared to a mini-American Serengeti for the diversity of large wild mammals that move across it. One partial antidote, a way to address to some of those bison grazing concerns instead of keeping the animals bottled up in the park, would be opening up more space outside Yellowstone. But the state of Montana has historically refused and only recently, owed to growing public pressure, has it been willing to consider offering bison greater flexibility to be bison.

Expecting any wild animal to remain contained behind an invisible human line drawn on a map that does not conform to the biological need of the species defies not only logic but the laws of nature. It may be what ranchers do with non-native livestock, by stringing barbed wire and pasturing animals bred to be docile, but wildlife biologists say it has no grounding in sound 21st-century ecology, ethical treatment or respect for a beloved national symbol that is on the seal of the U.S. Interior Department.

Notably, bison are the only species in the Greater Yellowstone Ecosystem that are not allowed to naturally migrate or roam. Elk and mule deer can, so too pronghorn and moose, trumpeter swans and fish. Montana’s intolerance of bison cannot, with any semblance of truth, be based upon the threat of brucellosis so what is the real reason?.

Brucellosis is a serious, highly-contagious zoonotic disease and in bovine animals involves a bacteria Brucella abortus . In the past, it was considered more a health threat to humans who drank unpasteurized milk. In wildlife and livestock, B. abortus does not cause animals to die nor is it population limiting. It is more of a trade issue with barriers put up against states that have brucellosis in their livestock herds. In female animals, be they bison, elk or cattle, it causes pregnant mothers to abort their first calves but generally does not affect reproduction afterwards. For 40 years, it was thought that bison represented the greatest threat of transmission.

“During my time in Yellowstone, I have watched with great interest — and some amazement — that bison are vilified as the primary threat or vector for brucellosis transition in the ecosystem,” Yellowstone Superintendent Dan Wenk wrote in the peer-reviewed book Yellowstone Bison: Conserving an American Icon in Modern Society. “There is an illusory belief that if brucellosis were eliminated in bison it would be eliminated from the ecosystem. The authors [in this book] clearly state that this scenario is unlikely and that bison make up a small portion of the overall risk for brucellosis transmission to cattle.”

Edited by P.J. White, Rick Wallen, and David Hallac, this is a probing, exhaustive analysis of the bison controversy and one that should be required reading for every state legislator in Montana, every member of the state departments of Agriculture, Livestock and Fish, Wildlife and Parks, and, if you care about bison, every nature-loving citizen. Mountain Journal readers can download a free copy by clicking here

The book’s conclusions are even backed by the most prestigious and respected scientific body on earth, the National Academies of Sciences . As the NAS noted in its blue-ribbon report, Revisiting Brucellosis In the Greater Yellowstone Area released last summer ( you can read it online ), there has never been a documented case of a wild Yellowstone bison transmitting brucellosis to domestic livestock. Not a single case. All the instances involving brucellosis transmission from wildlife to cattle have involved wild elk.

Bison numbers and distribution are already controlled at the boundaries of Yellowstone, which is inconsistent with the natural regulation policy of the National Park Service," it concluded and added, " Reducing the elk population is an option for reducing the risk of transmission among elk, cattle, and bison."

. The National Academies acknowledged in writing that Yellowstone, through the Interagency Bison Management Plan , is forced to violate its own management philosophy. "

Another noteworthy take-home finding from the National Academies report is this: "Ecological changes within the Greater Yellowstone Area since 1998 have shifted the dynamics of wildlife populations. The reintroduction of wolves and increases in grizzly bear numbers have impacted the density and distribution of elk. Elk populations have expanded on the periphery of the Greater Yellowstone Area but have decreased inside Yellowstone. The rising number of private landowners has changed how land is used around national parks, with private lands increasingly serving as refugia for elk from hunting."





It also shines light on the National Elk Refuge in Jackson Hole and Wyoming's 22 state-run elk feedgrounds, noting that they are troublesome reservoirs of disease. "Any gains in reducing seroprevalence [of brucellosis] in Yellowstone bison [by killing them] could be negated by exposure of remaining bison to infected elk within Yellowstone and in elk feedgrounds if concurrent efforts to reduce seroprevalence in elk does not occur. This is particularly important for the Jackson bison herd, for which exposure to elk on the National Elk Refuge continues to be a significant risk, and will need to be considered in bison control plans."





Molecular genetic characterization of B. abortus isolates from elk, bison, and cattle indicate that Wyoming feedgrounds have the greatest diversity of B. abortus lineages, and strongly suggest that they are the initial source of infection for other elk populations in the Greater Yellowstone Area." The Academies added this glaring reference: "





How might the Wyoming feedgrounds, which have been a reservoir for brucellosis and other diseases, accelerate the dispersal of Chronic Wasting Disease once it arrives there and at the National Elk Refuge?