The influence of climate on past, present, and future conservation translocations

Abstract

A large proportion of conservation translocations fail to establish viable populations. Managers often attribute translocation failure to environmental conditions at recipient sites, however, no study has attempted to quantify the importance of environmental conditions, such as climate, in determining past translocation outcomes. In this thesis, I investigate the potential effects of recent and future climatic conditions on translocated populations of ectothermic vertebrate and invertebrate taxa across the globe. Using species distribution modelling techniques, I contrast predicted climate suitability between sites of successful and unsuccessful translocation programmes. I find that the probability of translocation success increases as predicted climate suitability increases. Furthermore, when contrasting the effect of climate suitability against five other variables often considered in the peer-reviewed literature as important to translocation outcome, climate suitability exerted the strongest effect and explained the most variation in translocation outcome. While these results highlight the potential of predicted climate suitability to inform translocation management, the rapidly changing climate means that matching species climatic preferences to existing conditions will be insufficient to secure the long-term viability of translocated populations. I demonstrate this by projecting species distribution models (SDMs) onto scenarios of future climate change for species that have been successfully established through translocation. SDMs project that at least 74% of recipient sites will decline in suitability in the future, and alarmingly, this percentage is based on an optimistic scenario of greenhouse-gas emissions for the near-future (2021-2040). The final data-chapter of this thesis applies the findings and methodologies of the preceding chapters to support conservation decision-making in an ongoing translocation programme in the North West of England, by using SDM outputs to facilitate the prioritisation of translocation efforts towards species with the greatest likelihood of establishing long-term populations under climate change. My findings call for greater integration of the spatiotemporal properties of climate into translocation management planning and suggest that SDMs offer an effective tool for achieving this.