Eradication of feral pigs from the Northern Channel Islands, California

Nonnative ungulates can be highly destructive to island ecosystems and eradication is often necessary to abate threats they pose to native species. A number of feral animal removal programs have been undertaken in past decades on the five northern Channel Islands of California that comprise the Channel Islands National Park. Here, we focus on the recent program to eradicate feral pigs (Sus scrofa) from Santa Cruz Island. We outline the scientific underpinnings that led to a conclusion that eradication was the necessary and preferred action, and discuss the strategic and operational plan for conducting eradication on the large (243 km²) and complex island with two landowners. We contrast that plan with the approach used to eradicate feral pigs from neighboring Santa Rosa Island, which although comparable in size, differs dramatically in terrain and vegetation cover. The Santa Rosa program also occurred prior to the general availability of many tools (e.g., GPS, GIS, and telemetry technologies) that were integral to the Santa Cruz program. We describe how we used such technologies not only to enhance efficiency and reduce uncertainty (and so risk of failure) in the program, but also to help reduce risk of perverse effect of the eradication on non-target species, specifically the Santa Cruz Island fox. The approach we used on Santa Cruz Island enabled us to achieve eradication, with a quantified degree of certainty, in a rapid timeframe for an island of its size. We suggest that this approach can be generalized as a model for island eradication efforts elsewhere, and that if used, could reduce many of the risks inherent in eradication programs and enable more ambitious goals to be set for protection and restoration of unique island biota.