Balancing development and biodiversity conservation presents significant challenges. One approach, biodiversity offsetting, represents “measurable conservation outcomes resulting from actions designed to compensate for significant residual adverse biodiversity impacts resulting from project development” and is a final step in a mitigation hierarchy following steps of avoidance, minimization, rehabilitation, and restoration. In the journal Conservation Biology, Josh Donlan and colleagues at Island Conservation recently presented an argument for the potential for biodiversity offsetting to fund invasive species eradications on islands. Islands have disproportionately higher levels of biodiversity, threatened species, and extinctions than mainlands.
The eradication of invasive species from islands is a conservation intervention proven to protect biodiversity, with more than 1200 successful vertebrate eradications implemented globally. The demand for eradication projects is increasing and practitioners are planning projects on increasingly larger, more remote and more technically challenging islands. Undertaking strategic planning for conservation requires information on both the cost and benefit of proposed actions, to determine the trade-off in selecting one project over another. To date the cost of eradication projects is disparately reported in the literature, an artefact of different reporting requirements based on where the eradication was undertaken, the scale of the project, the implementing agency and its accountabilities, and inconsistency in reporting all project component costs. Eradication projects have characteristics that allow more refined cost forecasting relative to other conservation initiatives, including a narrow set of major eradication techniques being used, a defined beginning and end point, and distinct project components. Here we present the major cost centres for eradication projects, including a dataset for a suite of rodent, ungulate and predator eradications, using a dataset of 46 eradications primarily from New Zealand, Ecuador and the USA. We found cost increased with island size for all eradication types except ground based rodent eradications. Using these standards to report project costs will improve the ability to evaluate and predict the cost of removing invasive animals from islands to protect native insular biodiversity.
Conservation practitioners are increasingly embracing evidence-based and re- turn on investment (ROI) approaches. Much evidence now exists that docu- ments island biodiversity impacts by invasive mammals. The technical ability to eradicate invasive mammals from islands has increased exponentially; con- sequently, strategic planning focused on maximizing the ROI is now a limiting factor for island restoration. We use a regional ROI approach to prioritize erad- ications 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 un- der 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 interven- tions were nested with increasing thresholds, and (3) helped justify larger in- vestments 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.