Trap evaluation to optimize wild pig removal efforts in remote settings

Context Invasive wild pigs (Sus scrofa) are the most abundant, widespread, and economically significant large vertebrate established in the Hawaiian Islands. Owing to their generalist diet and rooting behavior, wild pigs alter soils and watersheds, negatively affecting native biota. Aims Lethal removal of wild pigs by trapping is often the most effective and practical management action to reduce their impacts, but terrain and access are challenging. Methods We compared the effectiveness and efficiency of three trap designs (i.e. corral, box, and passive net traps) on a fenced population of wild pigs in a remote montane forest setting on the Island of Hawai‘i, where use of cellular-activated ‘smart’ traps was not possible. Key results During three high-intensity removal efforts between 30 November 2021 and 8 May 2022, we trapped and euthanized 435 wild pigs through 162 trapping events. Although each trap type effectively captured wild pigs, passive net traps captured more wild pigs per capture event than did corral and box traps. Specifically, when using passive net traps, we captured approximately four wild pigs per capture event, which was two to three times more than with corral traps and box traps respectively. Passive net traps were more effective and efficient than were box traps, although they performed similarly to corral traps. Conclusions All trap types we tested successfully captured wild pigs, but passive net traps typically captured more wild pigs per event than did traditional corral and box traps. Net traps were a valuable addition to remote trapping strategies. Implications In remote and rugged settings where smart trapping technology cannot be used, we recommend incorporating passive net traps into a trapping program to optimize removal of wild pigs.