Simulating Potential Population Growth of Wild Pig (Sus scrofa) in Texas
Author(s): Janell M. Mellish, Aaron Sumrall, Tyler A. Campbell, Bret A. Collier, William H. Neill, Billy Higginbotham, and Roel R. Lopez
Published: July 2014
Understanding the interrelationship of environmental and biological factors that influence population growth rates of invasive Sus scrofa (Wild Pig) is a requisite for population management of the species. Such information can be used to evaluate various types of population control to ensure that the most cost-effective damage-abatement methods are used. We developed a sex- and age-structured model to simulate general population dynamics of Wild Pigs in Texas. Our objectives were to estimate potential statewide Wild Pig population-growth rates for Texas, identify model parameters that most influenced population trajectories, and compare resulting model predictions with ancillary population-trend data. Our Wild Pig simulation model estimated a mean annual growth rate of 0.32 (SE = 0.01), and stochastic model projections of Wild Pig population sizes ranged from 3.6 million to 16.9 million after 5 years. To evaluate parameter sensitivity, we recast our simulation results into a Bayesian belief network, and evaluated input-parameter influence based on variance reduction using Shannon’s measure of mutual information. Our results indicated that the most influential model parameters within our simulation were number of litters per female and number of piglets recruited into the population, while adult and juvenile survival had little influence on Wild Pig population size within our simulations. Overall, our results suggest that natural resource managers should focus efforts towards reducing Wild Pig reproductive success, as opposed to attempting to increase adult mortality, when conducting Wild Pig population-control campaigns.
Mellish, J.M, A. Sumrall, T.A. Campbell, B.A. Collier, W.H. Neill, B. Higginbotham, and R.R. Lopez. 2014. Simulating potential population growth of wild pigs (Sus scrofa) in Texas. Southeastern Naturalist 13:367-376.