The challenge of designing meaningful performance measures for evaluating the success of conservation translocations

Conservation translocation is a valuable management tool for conserving and restoring biodiversity. Conservation managers and researchers strive for translocation success and spend considerable time and energy planning for a positive outcome. However, many translocations fail. Defining what makes a translocation ‘successful’ can be challenging. Criteria for success must be relevant to the objectives of the translocation, should be measurable and have realistic timeframes for achievement. How we evaluate these criteria is highly dependent on our ability to monitor a species effectively, which may be complicated by its behaviour, the release methods used, or the release environment, including sympatric species. Well-planned, but ultimately ineffective, monitoring strategies may render some criteria difficult or impossible to evaluate. Finally, poorly defined success criteria may result in apparently successful translocations failing to achieve their stated goals, or translocations that meet their success criteria but ultimately fail. Here, we discuss the challenges faced when defining and evaluating the success of a fauna reconstruction program on Dirk Hartog Island in Western Australia. Our achievement of success criteria within prescribed timeframes has been mixed, highlighting ways to better define and measure success. We discuss how we have adapted to new knowledge as the translocations progressed and propose frameworks for defining performance measures and guiding decision-making in response to failures in achieving success criteria.