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Open Access Publications from the University of California

Grappling with Wild Pigs in California High Country: Wild Pig Population and Disturbance Research at Tejon Ranch


Wild pigs cause extensive damage to ecological resources, agricultural lands, and private property, and carry diseases that may pose a health risk to livestock and humans. At the Tejon Ranch in the Tehachapi Mountains of California, a population of wild pigs produce extensive ecological and economic damages, and share rangelands with cattle. Via the Tejon Ranch Conservation and Land Use Agreement, the Tejon Ranch Conservancy is charged with the science-based stewardship of over 970 km2 of conserved lands at Tejon Ranch. During the summer of 2014 we initiated pilot field research to develop monitoring and control methodologies to better manage wild pigs and associated disturbance across Tejon Ranch’s conserved lands. We compared line transect surveys (LTS) with remotely triggered wildlife trap-cameras as alternative methods to estimate pig abundance. Density estimates were made from LTS survey results using program DISTANCE, while indices of abundance were developed from camera trap data. We also estimated ecological disturbance by measuring the amount of pig rooting along segments of LTS transects. Wetland areas, along with higher elevation interior habitats received more damage than dryer, lower elevation habitats, which was expected given our summer surveys. Expanding on these pilot abundance surveys, we are now attempting to achieve more precise population density estimates using mark-resight techniques through a combination of trapping and collaring animals as well as individually identifying pigs from their unique pelage patterns.

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