Feral swine, often called wild pigs, are a widespread and damaging invasive species threatening the Hawaiian ecosystem. These animals are descendants of the smaller Polynesian pig and the larger European boar introduced later, and they are now found across six of the seven main islands. Their rooting behavior causes extensive soil disturbance, which promotes erosion, pollutes watersheds, and allows non-native plant species like strawberry guava to outcompete native flora. The pigs also create rain-filled wallows, and these stagnant pools become breeding grounds for mosquitoes that transmit avian malaria, a disease that has contributed to the decline of native forest birds. Effective control is necessary to protect the endemic plant life and the integrity of the island’s natural water systems.
Preventing Access Through Exclusion
Physical exclusion is the most reliable long-term strategy for protecting sensitive areas and agricultural fields from damage. Constructing perimeter fencing prevents pigs from accessing an area entirely. A successful barrier requires heavy-duty woven wire mesh, often referred to as hog wire, with a fixed-knot design for maximum strength.
The mesh fabric should be at least 48 inches (1.2 meters) high to prevent pigs from jumping or pushing over the top. Since feral swine root, the bottom of the fence must be secured against tunneling. This is achieved by burying the wire a minimum of 6 to 12 inches below the surface or by laying a wire apron horizontally on the ground outside the fence line.
Electric fencing offers a supplementary or less costly alternative, particularly for agricultural land where permanent barriers are not feasible. These systems must utilize a low-impedance charger capable of maintaining a minimum of 5,000 volts on the line to deliver a non-lethal shock. Strategic wire placement is key, with the lowest hot wire positioned no more than six inches above the ground to target the pig’s sensitive snout. A two- or three-wire system is recommended, ensuring one wire is at the approximate shoulder height of an adult pig.
Trapping Techniques for Removal
Trapping is a highly effective, non-hunting method for landowners seeking to eliminate entire groups of pigs, known as sounders. Large, circular corral traps are significantly more effective than smaller box traps because they are designed to capture multiple animals simultaneously. Corral traps use rigid panels or strong netting, often 18 to 22 feet in diameter, with a one-way gate that allows continuous entry after the first animal passes through.
Success hinges on pre-baiting, where the trap is left unset for an extended period to acclimate the sounder to feeding inside the enclosure. Landowners should monitor the trap site, often using trail cameras, to ensure all individuals are habitually entering the trap before setting the gate trigger. This patience prevents “trap shyness” in surviving animals, making future captures more difficult.
The most common and effective bait is fermented corn, prepared by soaking cracked corn in water for up to a week to sour it. The fermentation process can be accelerated by adding a sugary liquid, such as fruit juice, and a packet of yeast. This strong, sour odor is highly attractive to pigs but less appealing to non-target species. Once the entire group is confirmed to be feeding within the trap perimeter, the gate is set for a whole-sounder removal.
Active Removal Through Hunting
Hunting provides a means of active removal for population control, especially in mountainous or remote terrain. On public hunting lands, the Department of Land and Natural Resources (DLNR) Division of Forestry and Wildlife (DOFAW) regulates seasons, bag limits, and allowed methods. On private property, a valid Hawaii hunting license is required, but hunting is permitted year-round with the express permission of the landowner.
Methods range from modern firearm hunting with rifles to the traditional practice of using trained dogs to locate and corner the pig, which is then dispatched with a knife. Safety is a major concern, and hunting is strictly limited to the period between a half-hour before sunrise and a half-hour after sunset. Hunters must be aware of their surroundings when discharging a weapon, as negligence or hunting without permission can result in severe legal penalties enforced by the Division of Conservation and Resource Enforcement (DOCARE). Landowners must ensure all hunters comply with state laws regarding firearm possession and safety.
Navigating Regulations and Disposal
Removing pigs requires navigating specific administrative and environmental rules to ensure compliance. While hunting on private land requires a license and permission, property owners experiencing damage may apply to the Board of Land and Natural Resources (BLNR) for a nuisance control permit. This permit authorizes the destruction or control of game mammals causing damage and specifies the approved removal method.
Once a pig is dispatched, the landowner is legally responsible for the proper disposal of the carcass according to Hawaii Administrative Rules (HAR). The primary disposal method is immediate on-site burial to prevent the spread of diseases, such as swine brucellosis, and to avoid attracting scavengers. Carcasses must be covered with a minimum of two feet (0.6 meters) of compacted earth. Alternative disposal options, such as composting or incineration, require specific approval and permits from the Department of Health to avoid environmental contamination, especially in watershed areas.