The Risks of Assisted Colonization

There is a growing debate over whether species should be translocated outside their historic ranges to deal with extinction risks as habitats shift due to climate change. This idea of taking preemptive action to avert predicted extinction risks has been given emphasis by the recent International Union for Conservation of Nature (IUCN) assessment of species susceptibility to climate-change impacts (Foden et al. 2008), prompting suggestions that “more aggressive measures, such as so-called ‘assisted migration’” be considered (Marris 2008). Hoegh-Guldberg et al. (2008) provide a decision framework for identifying scenarios in which what they term “assisted colonization” (AC) is justified. We see problems with the impact of these articles, despite their conservative approach. First, there are current international translocation guidelines (IUCN 1998) that provide a strong rationale against the early adoption of AC as a conservation tool. The Reintroduction Specialist Group (RSG) was created in 1988 to address the proliferation of ill-conceived translocations that had been taking place, including many releases of species outside historic ranges (Stanley Price & Soorae 2003). The RSG formulated the guidelines for translocation planning to ensure that conservation benefits accrue. “Benign introduction” (BI)—the translocation of species to suitable habitat outside their historic range as a conservation measure—was considered appropriate only when there was no habitat left within the original species range (IUCN 1998). Although AC appears to fall within the definition of BI, the two differ in that AC aims proactively to establish species outside their historic range to preempt predicted climate-driven changes in habitat suitability. Calls to take proactive conservation measures need to consider that there are currently huge uncertainties involved, not only in climatechange predictions and consequent species responses (Araújo et al. 2005; Hulme 2005; Sekercioglu et al. 2008) but also in our understanding of the habitat requirements of species (Stamps & Swaisgood 2007) and the effects of translocations on ecosystem function (Armstrong & Seddon 2008). At a recent conference (First International Wildlife Reintroduction Conference, Lincoln Park Zoo, Chicago, Illinois,April2008, http://www. reintroduction.org/), RSG members discussed climate-change implications for translocations, acknowledging the need for the integration of reintroduction biology and restoration ecology, and the updating of translocation guidelines to consider issues such as the mitigation of climate-driven habitat change and overcoming barriers to natural dispersal of species. Given current uncertainty, however, there is substantial risk that prematurely embracing the undeniably sexy AC concept will initiate a new era of ill-conceived species translocations. Philip J. Seddon,∗ Doug P. Armstrong,† Pritpal Soorae,‡ Frederic Launay,§ Sally Walker,∗∗ Carlos R. Ruiz-Miranda,†† Sanjay Molur,∗∗ Heather Koldewey,‡‡ and Devra G. Kleiman§§ ∗RSG Bird Section Chair, Department of Zoology, University of Otago, Dunedin, New Zealand, email philip.seddon@stonebow. otago.ac. nz †RSG Australasia Chair, Massey University, Palmerston North, New Zealand ‡RSG Programme Officer, Environment Agency, Abu Dhabi, United Arab Emirates §RSG Chair, Environment Agency, Abu Dhabi, United Arab Emirates ∗∗RSG South Asia co-Chair, Zoo Outreach, Coimbatore, India ††RSG Meso-South America Chair, Environmental Sciences Laboratory, Universidade Estadual do Norte Fluminense, Rio de Janeiro, Brazil ‡‡RSG Fish Section Chair, Zoological Society of London, London, United Kingdom §§RSG North America Chair, Zoo-Logic, Chevy Chase, MD 20815, U.S.A.