Maximizing return on investment for island restoration and species conservation

Conservation practitioners are increasingly embracing evidence-based and return on investment (ROI) approaches. Much evidence now exists that documents island biodiversity impacts by invasive mammals. The technical ability to eradicate invasive mammals from islands has increased exponentially; consequently, strategic planning focused on maximizing the ROI is now a limiting factor for island restoration. We use a regional ROI approach to prioritize eradications on islands for seabird conservation in British Columbia, Canada. We do so by integrating economic costs of interventions and applying a resource allocation approach. We estimate the optimal set of islands for eradication under two conservation objectives each with a series of increasing thresholds of population sizes and breeding locations. Our approach (1) identified the most cost-effective interventions, (2) determined whether or not those interventions were nested with increasing thresholds, and (3) helped justify larger investments when appropriate. More often than not, conservation decisions are made at a regional scale, and decision-makers often must make choices on how to allocate funds across a number of potential conservation actions. A regional, ROI framework can serve as a decision-support tool for organizations engaging in discrete interventions in order to maximize benefits for the minimum cost.