A local eradication pilot study of methods for feral pig eradication on Auckland Island

Since their liberation in 1807, feral pigs (Sus scrofa) have negatively impacted ecosystem health and processes on subantarctic Auckland Island, New Zealand. Eradication of invasive alien species is often critical to restoration programmes and preventing species extinctions. Eradication programmes utilising multiple techniques have allowed feral pig eradications on large islands. Protracted eradication programmes can have a higher risk of failure due to factors such as biological, logistical, social, and funding support. A temporary local pig eradication pilot study was successfully implemented on a densely vegetated fenced 951 ha peninsula on Auckland Island, emulating the principles set out during the Santa Cruz Island (California, USA) eradication. We applied multiple techniques, each delivered at the appropriate pig population density and within a finite period, to reduce the inherent risk of eradication failure. Aerial hunting was used to reduce the pig population before systematic ground hunting by a team using specially trained dogs removed survivors and validated eradication success. The deployment of a high specification thermal or forward-looking infrared (FLIR) camera in a particular manner greatly improved the efficiency of aerial hunting during this pilot study. The use of passive trapping, Judas pigs and division of the island into smaller fenced units are supplementary methods proposed for the Auckland Island eradication to enhance eradication efficiency as the methods implemented here are scaled up.