Research Project Assesses Wild Pig Damage, Removal Methods

Authored by: Faith E. Kruis, Justine L. Smith, Michael T. Mengak and L. Mike Conner

This article was originally published by Warnell School of Foresty & Natural Resources, University of Georgia, and can be found here.

Wild pigs are an invasive species in the United States, with population estimates exceeding 6 million across 31 states. Wild pig damage to agriculture, private property and natural resources exceeds $150 million annually in Georgia.

In 2018, the USDA Farm Bill created a program to protect agriculture, property, and natural ecosystems from the threat of wild pigs. 

One project, the Albany Area pilot project, is overseen by the Flint River Soil and Water Conservation District in collaboration with Jones Center at Ichauway and the UGA Warnell School of Forestry and Natural Resources. The goals of this project are to:

• Investigate the impact of wild pig removal on native fauna

• Assess damage in agricultural fields associated due to wild pigs

• Measure the efficacy of using the Judas technique as a removal method.

Wild pig removals are conducted by USDA APHIS Wildlife Services while research data are collected by graduate students in Warnell. 

Our study area spans 25,000 acres across six properties in Calhoun County, Georgia, and consists mainly of agricultural fields, wetlands and forests. Major crops include corn, peanuts, cotton and pecans.

We deployed passive camera traps across the properties from June 2020 to August 2022. We deployed 147 cameras for 781 days, capturing 560,239 photos of wildlife activity. These data will document wildlife occupancy trends in different habitat types across seasons. Since removals are constantly taking place in the study area, we will be able to identify whether wild pig presence, or lack thereof, has influenced wildlife occurrence. 

In May 2021, we began flying an unmanned aerial system over 14 row crop fields. Flights will continue during 2023. Data and images collected will help estimate percentages of fields damaged by wild pigs, identify potential characteristics that may influence location of damage, determine when the most damage takes place, and which crop is preferred by wild pigs. This information will help identify when peak removals should take place to minimize crop damage and maximize profits. 

Another study aspect is to use GPS collared pigs to locate other pigs. This technique, referred to as the Judas technique, involves marking and releasing one individual, the Judas pig, from a group of pigs and using it to locate other groups for subsequent targeted removal. We began GPS collar deployment in March 2021 and additional camera trapping in October 2021. Data collected on 13 wild pigs thus far demonstrate sex has no bearing on efficacy.

Data from this study provided ample opportunity for additional research studies. One paper already submitted to a scientific journal focuses on wild pig behavioral response to aerial gunning removal efforts. Results showed that wild pigs exhibit a learned avoidance response, shifting onset of daily activity from diurnal/crepuscular to more nocturnal. This study is unique as no prior studies have performed this analysis to identify wild pig responses to this removal technique.

The second study demonstrated the relationship between wild pig body mass and body measurements, which reduces the need for a scale to estimate body mass. Data indicated heart girth and total length as useful predictors of body mass for sexually immature pigs and sexually mature male pigs. Mature female body mass was predicted with neck girth, heart girth and total length.

The third project addresses the most efficient unmanned aerial system sampling method to identify wild pig damage in agricultural fields. Current ground-based sampling methods can be biased, costly or too time consuming. We compared ground-based transect measurements to three drone-based sampling protocols and assessed each flight regime for efficacy. Future economic assessments will improve as we identify which unmanned aerial vehicle sampling method is most efficient. This will also inform our decisions on when and where removal activities should take place.