Author: Marie Dade

Publisher:

Published: 2013

Total Pages:

ISBN-13:

Declining rainfall under current climatic trends is reducing the suitability of the current habitat of the Critically Endangered Western Swamp Tortoise (Pseudemydura umbrina) on the Swan Coastal Plain in Western Australia. Assisted colonisation, a conservation translocation of a species to an area outside its current or historical range, has been proposed for this species. To ensure that suitable sites for assisted colonisation are identified, key habitat criteria must be present and the site must possess a suitable hydrological regime under current and future climatic trends. Therefore the aim of this study was to identify a suitable assisted colonisation site for P. umbrina by combining the outputs of hydrological modelling under a median future climate scenario with other habitat criteria, using a multiple criteria analysis.Habitat and hydrological criteria were mapped using geographical information systems to create a suitability index highlighting potentially suitable areas for P. umbrina under a median future climate scenario. Eight potentially suitable wetland sites were then selected to conduct ground-truthing for each of the criteria and to subsequently be ranked based on a weighted summation method, with criterion weights calculated using both pairwise comparisons and expert opinion.This study shows that sites closest to P. umbrina's current habitat are more suitable than those further away. However, it is recommended that a larger number of criteria and sites are assessed and sampled before a final decision can be made on the optimal assisted colonisation site for P. umbrina. Expert opinion was a highly accurate approach for identifying criterion weights for P. umbrina, however for other species it is recommended that the pairwise comparisons approach be used to reduce the risk of bias. Overall, this study showed suitable sites for assisted colonisation are likely to be within the same biogeographical region as P. umbrina's current habitat and suggests extensive ground-truthing should be conducted to determine the level of inaccuracy in the spatial data used to identify suitable habitat.