Concerns over migratory bison (Bison bison) at Yellowstone National Park transmitting brucellosis (Brucella abortus) to cattle herds on adjacent lands led to proposals for bison vaccination. We developed an individual-based model to evaluate how brucellosis infection might respond under alternate vaccination strategies, including: (1) vaccination of female calves and yearlings captured at the park boundary when bison move outside the primary conservation area; (2) combining boundary vaccination with the remote delivery of vaccine to female calves and yearlings distributed throughout the park; and (3) vaccinating all female bison (including adults) during boundary capture and throughout the park using remote delivery of vaccine. Simulations suggested Alternative 3 would be most effective, with brucellosis seroprevalence decreasing by 66% (from 0.47 to 0.16) over a 30-year period resulting from 29% of the population receiving protection through vaccination. Under this alternative, bison would receive multiple vaccinations that extend the duration of vaccine protection and defend against recurring infection in latently infected animals. The initial decrease in population seroprevalence will likely be slow due to high initial seroprevalence (40?60%), long-lived antibodies, and the culling of some vaccinated bison that were subsequently exposed to field strain Brucella and reacted positively on serologic tests. Vaccination is unlikely to eradicate B. abortus from Yellowstone bison, but could be an effective tool for reducing the level of infection. Our approach and findings have applicability world-wide for managers dealing with intractable wildlife diseases that cross wildlife?livestock and wildlife?human interfaces and affect public health or economic well-being.

Yellowstone National Park looks like a pristine western landscape populated by its wild inhabitants: bison, grizzly bears, and wolves. But the bison do not always range freely, snowmobile noise intrudes upon the park's profound winter silence, and some tourist villages are located in prime grizzly bear habitat. Despite these problems, the National Park Service has succeeded in reintroducing wolves, allowing wildfires to play their natural role in park forests, and prohibiting a gold mine that would be present in other more typical western landscapes. Each of these issues--bison, snowmobiles, grizzly bears, wolves, fires, and the New World Mine--was the center of a recent policy-making controversy involving federal politicians, robust debate with interested stakeholders, and discussions about the relevant science. Yet, the outcomes of the controversies varied considerably, depending on politics, science, how well park managers allied themselves with external interests, and public thinking about the effects of park proposals on their access and economies. Michael Yochim examines the primary influences upon contemporary national park policy making and considers how those influences shaped or constrained the final policy. In addition, Yochim considers how park managers may best work within the contemporary policy-making context to preserve national parks.