Reaching zero, 20 years to eradicate non-native ungulates in conservation fences at Pohakuloa Training Area, Hawaii

Presented by Rogelio Ernesto Doratt (CEMML) at the National Military Fish and Wildlife Association’s 2019 annual meeting and training workshop. Non-native ungulates (sheep, goats, and pigs) are a serious threat to native species and ecosystems in Hawaii. At Pohakuloa Training Area (PTA) on Hawaii Island, dryland habitats support 26 threatened and endangered species, some exceedingly rare and most of which are negatively affected by non-native ungulates. In 1998, the U. S. Army Garrison – Pohakuloa began constructing conservation fence units and removing ungulates to protect the threatened and endangered species and their habitat. By 2013, 14 conservation fence units were completed to encompass 15,094 ha of dryland native habitat. Ungulate removal efforts were ongoing throughout construction and early eradication efforts (public hunting programs, professional ungulate removal contractors, and coordinated ungulate drives) failed to remove the ungulates inside the fence units. The lack of political support, inappropriate removal methods, and failure to remove the final animals at low densities allowed the ungulate populations to rebound to high densities. In 2014 a new ungulate control plan was created and implemented without interruption to reduce ungulate populations and prevent rebounding. The control plan was broken into 5 phases: Phase 1- removal of all ungulates detected in the fence units (search and remove), Phase 2- introduction of radio collared “Judas” ungulates followed by removal of all un-collared ungulates accompanying the Judas animals, Phase 3- removal of Judas ungulates, Phase 4- ground and aerial surveys to verify all ungulates were removed, and Phase 5- ungulate ingress monitoring. From 1998 to 2017, roughly 5,624 ungulates were removed and all 14 conservation fence units are considered ungulate-free. To keep the fence units ungulate-free, 4 types of monitoring projects were established: fence line inspections, camera surveillance, ungulate sighting reporting, and aerial surveys. Since 2017, monitoring efforts detected 5 ingress events. All ungulates were subsequently removed and PTA fence units remain ungulate-free.