Reducing Risk and Enhancing Efficiency in Non-native Vertebrate Removal Efforts on Islands: a 25 Year Multi-taxa Retrospective from Santa Cruz Island, California

Effective conservation of native biodiversity on islands often requires the eradication of destructive non-native vertebrates. There are risks in conducting an eradication project, however, including the risk that the effort will fail to remove all the individuals, and the risk that the removal of the species will trigger ecological cascades with unanticipated and undesired consequences. Managers must plan to reduce such risks, and also maximize the return on investment of the limited conservation resources available for restoration programs. I discuss four vertebrate removal projects implemented on Santa Cruz Island, CA, over the past 25 years: sheep, golden eagles, pigs, and wild turkey. Collectively, these projects illustrate general principles for reducing risks inherent in eradication projects and for enhancing efficiencies in delivering conservation outcomes. Lessons from this case study – such as the value of disciplined engagement of the target population, strategic sequencing of restoration projects, and intensification of effort through the application of advanced technologies – can be applied to help accelerate the restoration of island ecosystems elsewhere and so the conservation of highly imperiled island biota.