Proactive conservation or planned invasions? Past, current and future use of assisted colonisation

Assisted colonisation, the translocation of organisms with release in areas outside their indigenous range in response to threats such as climate change, was presented in the scientific literature only a few years ago as a new tool for species conservation. The idea of planned introductions for conservation is a controversial issue, prompting vigorous and sometimes ill-informed debate in the scientific literature. The broad consensus was that this represented a bold new direction that had merit but carried great risk. Unacknowledged by most commentators, assisted colonisation, by other names, was already taking place, and in Australasia was even a long-accepted part of the conservation management tool kit. In 2013 the IUCN recognised assisted colonisation as a legitimate, if inherently risky, conservation translocation, and set out a comprehensive set of guidelines for its application. We review the history of assisted colonisation, with a focus on Australasian projects moving species in response to threats within the indigenous range. We review the current status of assisted colonisation in Australasia and present two case studies to illustrate the application of new approaches for assisted colonisation planning: western swamp turtle (Australia), and hihi (New Zealand stitchbird). We conclude by considering future directions in the specific application of translocations for climate change mitigation in the region.