Wildlife-livestock conflict: the risk of pathogen transmission from bison to cattle outside Yellowstone National Park

Interactions between wildlife and domestic livestock have created conflict for centuries because of pathogen transmission, competition for space and food, and predation. However, the transmission of pathogens from wildlife to domestic animals has recently gained prominence, including H5N1 avian influenza from wild ducks to poultry, bovine tuberculosis from badgers to cattle, and brucellosis from elk and bison to cattle. The risk of transmission of Brucella abortus (the causative agent of brucellosis) from bison (Bison bison) to cattle around Yellowstone National Park (YNP) is a hotly debated topic and an important conservation issue. Here we use a model to integrate epidemiological and ecological data to assess the spatio-temporal relative risk of transmission of Brucella from bison to cattle outside YNP under different scenarios. Our risk assessment shows that relative risk is spatially and temporally heterogeneous with local hotspots, shows a highly skewed distribution with predominantly low risk, and is strongly dependent on climate and the abundance of bison. We outline two strategies for managing this risk, and highlight the consequences of the current adaptive management plan. Synthesis and applications. Our results provide a detailed quantitative assessment of risk that offers several advantages over projections of numbers of bison leaving Yellowstone National Park. They suggest that risk could be effectively managed with lower costs, but that land use issues and the larger question of bison population management and movement outside the park might hinder the prospect of solutions that will please all stakeholders. More broadly, our work provides a model framework for quantifying the risk of wildlife-livestock pathogen transmission to guide management actions.