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Data from: State-space modeling to support management of brucellosis in the Yellowstone bison population

Citation

Hobbs, N. Thompson et al. (2015), Data from: State-space modeling to support management of brucellosis in the Yellowstone bison population, Dryad, Dataset, https://doi.org/10.5061/dryad.181qq

Abstract

The Yellowstone bison (Bison bison) exemplifies the challenge of conserving large mammals that migrate across the boundaries of conservation areas. Bison in Yellowstone are infected with brucellosis (Brucella abortus). Their seasonal movements can expose livestock to infection. We developed a Bayesian state-space model to reveal the influence of brucellosis on the dynamics of the Yellowstone bison population and to inform decisions on bison management. A model of frequency dependent transmission was superior to a density dependent model in its ability to predict out-of-sample observations of the probability of horizontal transmission (mean square prediction error frequency model = 0.78, density dependent model = 0.91). Conditional on the frequency dependent model, the median transmission rate of brucellosis was 1.86 year-1 (95% equal-tailed credible interval, BCI = 1.5, 2.2). The median of the posterior distribution of the basic reproductive ratio (R0) was 1.76 (BCI = 1.47, 2.36). Seroprevalence of adult females varied around 60% during the last two decades; however only 13 of 100 adult females were infectious (BCI = 0.1, 0.15). Estimation of population growth rate (_) in the presence of brucellosis reflected the depressing effect of the disease on recruitment; _ for an infected population averaged 1.07 (BCI = 1.03, 1.11) and for a healthy population _ = 1.12 (BCI = 1.07, 1.16). We used forecasting with a five year horizon to evaluate the ability of different actions to meet goals for management relative to a no action alternative. Annually removing 200 seropositive female bison increased the probability of reducing seroprevalence below 40% by 30-fold relative to no action and increased the probability of achieving a 50% reduction in transmission probability by a factor of 110 relative to no action. Annually vaccinating 200 seronegative animals increased the probability of achieving a 50% reduction transmission probability by five fold over no action. Forecasts of the future state of the population became increasingly uncertain with increases in the forecast horizon. Our findings emphasize the necessity of iterative, adaptive management with a relatively short term commitment to action, a commitment that must be reevaluated frequently in response to new data and model forecasts.

Usage Notes

Location

Greater Yellowstone ecoystem