Evaluating Feral Pig Management Strategies at Tejon Ranch, California

Abstract

Feral swine are a serious management issue for natural resource managers, farmers, ranchers, and increasingly even suburban, private property owners. The 270,000-acre privately-owned Tejon Ranch in the Tehachapi Mountains of California, the subject of an historic conservation and land use agreement that conserved 90% of the property, supports a population of feral pigs that originally escaped from a private hunting ranch in the Tehachapi. Pigs now established on Tejon Ranch produce extensive ecological and economic damages, but are also a revenue source for the landowner's hunting program. The Tejon Ranch Conservancy serves as steward of the conserved lands and is evaluating management options to reduce feral pig damages, while respecting the landowner's right to maintain a hunting operation. To inform our management, we have modeled pig population responses to age-and sex-specific harvest scenarios. Consistent with previous studies, our models show that >70% of the population must be harvested annually to maintain or reduce the population, and that high harvest of adult females and juveniles is most effective at reducing abundance. Our analysis shows that population growth rates, which dictate harvest rates required for population control, are most sensitive to reproductive rates, and we have no site-specific data to estimate reproductive or mortality rates. As part of the National Feral Swine Damage Management Program, the Conservancy is partnering with the USDA Animal Plant Health Inspection Service on a research and monitoring project to estimate feral pig population size and demography; habitat use and home ranges; and damages at Tejon Ranch. The ultimate objective of the program is to evaluate techniques for reducing damages cause by feral swine.