Assisted colonization is a techno-fix

In a recent Opinion article in Trends in Ecology & Evolution, Ricciardi and Simberloff argue that species translocations are not a viable conservation strategy to deal with threats such as climate change, because conservation biologists lack sufficient understanding of the associated risks. We agree with the basic tenet of their argument that the attention and credibility given to such schemes is worrying and that it might send an overly optimistic message about assisted colonization to policymakers and the public. Here we propose three important additional considerations which lend further support to the view that the widespread implementation of assisted colonization will be inappropriate, especially when the broader social-ecological context of threatened species conservation is taken into account. First, assisted colonization does not address the root causes of extinction (i.e. in this context, human-induced climate change and habitat fragmentation). Instead, it is a ‘techno-fix’ restricted to treating the symptom of biodiversity loss, implying that no fundamental change in human activities is required. Second, widespread adoption of assisted colonization would divert resources, effort and expertise away from ambitious large-scale restoration and innovative management strategies in production landscapes. Third, without sufficient emphasis on reversing fragmentation, ongoing intensification of production landscapes will lead to even fewer species being able to move through them. Left with a yet more inhospitable matrix, both human and ecological response options to climate change will be further reduced, thereby potentially increasing dependence on assisted colonization. This reinforcing feedback could contribute to an undesirable path dependency similar to others documented in natural resource management, where technological solutions, once adopted, are the only viable options left. On this basis, assisted colonization is, at best, a band-aid to buy time for some species, but not a technological cure to the extinction crisis. Unforeseen risks, as highlighted by Ricciardi and Simberloff, need to be considered. Perhaps more importantly, we need to ask whether we want to build momentum for yet another techno-fix in natural resource management or try to build momentum to foster large-scale restoration, integration of conservation and commodity production, and reduction of greenhouse gas emissions. A mix of strategies will always be required for uncertain situations, and assisted colonization might have a place in biodiversity conservation if the risks of introducing species to new areas have been adequately assessed. The role of assisted colonization, however, needs to be carefully considered and will be small relative to other strategies that address the root causes of biodiversity decline.