From reintroduction to assisted colonization: Moving along the conservation translocation spectrum

Translocation, the intentional movement of living organisms from one area to another is increasingly being used as a conservation tool to overcome barriers to dispersal. A dichotomy exists for conservation-oriented translocations: on one hand, there are those that release plants or animals into known historic ranges and on the other hand, there are releases outside historic distributions. Misuse of or attempts to redefine established terms and a proliferation of variants of new terms such as assisted colonization, confuse and hamper communication. The aim of this opinion article is to describe and define a conservation translocation spectrum, from species reintroductions to assisted colonization, and beyond, and in so doing provide a standard framework and terminology for discussing translocation options. I suggest that we are moving along this spectrum, away from the dictates of historical species distribution records, toward the inclusion of more risky interventions that will be required to respond to habitat shifts due to anthropogenic impacts. To some extent rapid climate change changes everything, including how we should view introductions versus reintroductions. We need to seriously consider adding other approaches to our conservation toolbox. Assisted colonization will start us along this path, acknowledging as it does the accelerated rate of habitat change and the problems of attempting to preserve dynamic systems. The next step along the conservation translocation spectrum may be for reintroduction biology and restoration ecology to more comprehensively join forces on carefully selected projects to use species introductions to create novel ecosystems through active ecological community construction.