On Bison Science, Bison Politics, and the Rebisoning of the West

Bison at TNC’s Zapata Ranch near Great Sand Dunes National Park & Preserve. Jim Elder photo.

No animal in the National Park System is more iconic than Bison bison, that shaggy-headed beast that gives ground to nothing, not even wolves. How odd that these powerful, incredibly competent animals should be finding it so hard to thrive in the wild.

Many biologists now believe that a bright future for the bison as a wild species can only be assured by reintroducing genetically pure, free-roaming herds to some large areas of their former range. It’s not enough, they say, to keep wild bison confined to a handful of isolated habitats not sufficiently large and diverse to satisfy their needs.

The International Union for Conservation of Nature (IUCN) recently published American Bison: Status Survey and Conservation Guidelines 2010, which reports on the status of wild and conservation-herd bison, makes bison conservation recommendations, and unavoidably stirs controversy over emotion-charged issues such as proposals to “rebison” some sparsely settled and lightly developed parts of the western U.S. The full IUCN report, the work of nearly three dozen authors/contributors and editors C. Cormack Gates, Curtis H. Freese, Peter J.P. Gogan, and Mandy Kotzman, is available online at this site. For those who haven’t the time or inclination to read all 10 chapters of the 154-page, data laden document, there is an Executive Summary (page xv) that presents the salient facts and conclusions.

Whatever you may think of this report’s conclusions and recommendations, you’ll find it hard to fault on technical grounds alone. American Bison is a comprehensive, authoritative work rooted in scientifically rigorous research. Some might say that it is the very embodiment of the concept “bison science.” We can expect this report’s influences to be felt far and wide, and for a long time to come. It will be a standard citation in peer-reviewed bison literature, and its findings and recommendations will influence policy- and decision-making related to the management of bison on both public and private lands.

This is a timely publication. Bison management on and near public lands in the Western states has become a hot-button issue in recent years, and bison-related conflicts are certain to heat up even more dramatically in the near future. Some of the proposed changes in current bison management strategies and tactics could heavily impact land use on millions of acres of public and private property, affecting hundreds of communities and many thousands of individuals and businesses. The ecological, cultural, political, and economic stakes involved are, in a word, enormous.

The National Park Service has a major role to play in this arena. The agency not only has thousands of bison in its care – including most of the genetically pure animals needed for restocking – but has also acquired valuable experience in the tricky business of managing bison with due regard for the rights and wishes of neighbors.

The latter capability is a key asset, given that bison politics routinely trumps bison science. The clearest evidence of this can be seen near the northern border of Yellowstone National Park, where fears of bison-spread disease and other factors have long been used to justify preventing Yellowstone’s northern herd from accessing land outside the park that it needs for winter shelter and food.

At Grand Teton National Park and the adjacent National Elk Refuge, bison management is inextricably linked to – and greatly complicated by -- elk management. The conservation herds at Badlands, Wind Cave, and Theodore Roosevelt national parks are confined within their respective park borders. At Tallgrass Prairie National Preserve in Kansas, ranchers tolerate the preserve’s newly-acquired bison because the herd is small, confined by stout fencing, and managed more or less like livestock.

Even the distribution of genetically pure bison involves legal entanglements (as witness the legal challenge that conservation NGOs have mounted to bar Montana’s proposed privatization of some of Yellowstone’s wild bison).

Managing wild bison is difficult, even under the best of circumstances. The American bison is a large, potentially dangerous animal that gathers in herds, needs plenty of room, attracts large predators, carries infectious diseases, and is inclined to roam where it pleases, easily crossing or destroying fences designed for cattle. As the saying goes: “Sure, you can herd buffalo ….. anywhere they want to go.”

Unlike domestic cattle, which have been dumbed-down to utter dependency, free-roaming bison are incredibly tough, adaptable, and capable of migrating long distances. They have a high intrinsic reproductive rate too, which is why there were tens of millions of wild bison as recently as the 1860s. Bison certainly could, if given the opportunity, reestablish themselves as the top herbivores on millions of acres in the Great Plains.

Their presence would make a huge difference, too. Bison are “ecosystem engineers” because they can profoundly influence ecosystem structure and species diversity, energy flows, and nutrient cycling. When you return free-roaming bison to the land, you set the stage for broadly-based ecological restoration.

Although the thought of having bison, wolves, prairie grasses, and other native flora and fauna reclaim large swaths of the western Great Plains excites many conservationists, it sparks loathing in nearly all of the region’s communities. Taming the frontier and making land available for livestock grazing, farming, logging, mining, and other economic purposes was one of this country’s greatest achievements. Why give this hard-won land back to the bison and wolves?

Back in 1987, Rutgers University professors Frank and Deborah Popper had the temerity to bring that question out in the open. They suggested that much of the overgrazed, carelessly farmed, and sparsely settled Great Plains might logically be withdrawn from agricultural land use and converted to a “Buffalo Commons” in which natural ecosystem rhythms and balances would prevail. This idea of “rebisoning” abused Western lands to restore them to health gained a good bit of traction with some social scientists and conservationists, but outraged Great Plains residents and had no significant impact on public policy.

More recently, there has been some debate over a proposal to rebison several sparsely populated counties of western Kansas where agriculture can no longer support economically healthy communities. Already, an American Prairie Foundation-sponsored “rewilding” program is reintroducing bison on private land in the Missouri Breaks region of north-central Montana with the long-term goal of creating a prairie grasslands preserve bigger than Yellowstone National Park.

And now this IUCN report presents a scientific case for the “full recovery” of bison through “ecological restoration” on tracts of land sufficiently large and diverse to “permit full expression of natural [behaviors] and ecosystems functioning in ways similar to those of the past.”

Evaluating possible candidates for rebisoning projects is a very tricky business. Even the most sophisticated simulation models yet developed cannot adequately take into account all of the needs and wants and apprehensions of the many stakeholders involved. Thus, while population viability analysis (PVA) and population habitat viability assessment (PHVA) models can be used to evaluate potential restoration or reintroduction projects, it is the non-quantifiable subtleties of bison politics (a variable that PHVA modeling tries to incorporate) that will determine the feasibility of any rebisoning project under consideration. In brief, what’s going on in people’s heads matters more – much more – than what’s going on in bison herds.

For additional information about the intricacies of rebisoning, which is far more complicated than you might imagine, read the report’s concluding chapter, Conservation Guidelines for Population, Genetic, and Disease Management.

Now that rebisoning proposals and initiatives are getting more scientific support and more national publicity, it’s interesting to speculate how the National Park Service might be impacted.

You don’t need a crystal ball to see at least this much: Even if rebisoning proposals fail to win widespread support (as seems likely), vigorous debate will change the public perception of bison and push the federal and state governments toward key decisions about whether and to what degree rebisoning should be discouraged or facilitated.

The perceptual shift is no small matter. It’s one thing to have the bison in the national parks and other federal lands conceptualized as conservation herds that entertain people while preserving the genetically pure bison strain and a reasonable semblance of natural bison behavior in modestly-scaled islands of natural habitat. It’s quite another thing, however, to have bison under federal management depicted as forerunners of, and feedstock for, a rebisoning movement that threatens the vital interests of a diverse assortment of ranchers, energy companies, irrigation farmers, loggers, miners, railroads, the military, and other stakeholders throughout the historic bison ranges.

What the federal and state governments will do, especially after these stakeholders really get their hackles up, remains open to speculation. It seems clear enough, however, that bison translocation and restocking programs will be more tightly regulated, and that anything even potentially bison-related – wilderness designation and wolf management, to name just two – will be given an extra measure of scrutiny for its rebisoning implications.

These are certainly interesting times for federal bison managers.


A thoughtful and fair article written by a cool head. Thanks.

How about rebisoning the Valles Caldera?