Modeling and Monitoring Brucellosis in Yellowstone Bison

Introduction Yellowstone National Park has completed an Interagency Bison Management Plan (IBMP) that provides an adaptive management framework for long-term research and management of the Yellowstone bison (NPS 2000). The objective of the IBMP is to "maintain a wild, free-ranging population of bison and to address the risk of brucellosis transmission to protect the economic interests and viability ofthe livestock industry in the state of Montana" (NPS 1998). The IBMP addressed vaccination as a potential action (NPS 2000), and the National Park Service (NPS) proposes to implement a program to conduct remote vaccinations of wild, free-ranging bison for brucellosis within the boundaries of Yellowstone National Park. Yellowstone's Bison Ecology and Management Office (BEMO) is tasked with carrying out the management needs described in the IBMP and implementing a long term strategy for monitoring ecological data that describes demographic and habitat-related processes for basing future management decisions. As directed in the IBMP, the NPS is responsible for completing an environmental impact statement (EIS) to assess remotely vaccinating Yellowstone bison. The objective of this EIS is to evaluate the demographic consequences of implementing a remote vaccination program that will reduce the risk of brucellosis transmission from bison to cattle. In an adaptive management framework, decisions need to be made despite incomplete information, and predictive models provide managers with a tool to evaluate potential outcomes. The complexity of disease management in free-ranging bison requires such models for decisionmaking. In addition to modeling the consequences of vaccinating bison, a long-term monitoring program that integrates bison ecology with management objectives is necessary for understanding the impacts of implementing a vaccination program. Monitoring the ecological factors that influence bison movements to special management areas at park boundaries will link management objectives with ecological monitoring. The IBMP used a stochastic model to provide information for comparing the proposed management alternatives. Model predictions were general estimates of bison population abundance and brucellosis seroprevalence relative to each alternative. To assess the environmental consequences of initiating a remote vaccination program, a similar model describing vaccination effects on disease prevalence will be necessary for the upcoming EIS. The success of this program requires evaluating the state of the Yellowstone bison population before and after initiating remote vaccination. Therefore, monitoring is a necessary component of the remote vaccination program.