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Many species with restricted ranges or poor dispersal ability will occupy suboptimal habitats under climate change. The practice of translocating populations to more suitable areas outside the known historical range (assisted colonization) has been advanced as a solution to reduce the risk of extinction in the wild. Due to the high-risk and bureaucratic complexities of assisted colonization, it is imperative that a systematic process is used to select release sites that have a reduced likelihood of translocation failure. Here we demonstrate how a spatially explicit, three-stage multiple criteria analysis ( MCA) can be used to identify potentially suitable sites for assisted colonization of an endangered species. We employ this method as an initial screening process, prior to final selection of sites for assisted colonization of the critically endangered western swamp tortoise ( P seudemydura umbrina). This species occurs naturally in two small reserves in southwestern Australia, and is currently threatened by a shift to a drier climate and consequent changes to hydrological regimes. A literature review, characteristics of remnant P . umbrina habitat, and expert knowledge were used to create a composite index of habitat suitability, mapped across the entire south-west bioregion of Australia. The most suitable sites were 150 to 250 km south of the known range of P . umbrina, in areas of high landscape connectivity and low human population density. A subset of sites were examined in further detail and ranked using weighted summation. Careful use of MCA, taking into account data uncertainties and differences in expert opinion, can be a valuable tool when evaluating novel habitats for threatened species. [ABSTRACT FROM AUTHOR]

Understanding the factors that drive the dynamics of remnant populations of long-lived species presents a unique challenge for conservation management. The long-lived Brothers Island tuatara Sphenodon guntheri is represented by one natural, self-sustaining population on 4-ha North Brother Island, New Zealand, and two small, translocated populations. The North Brother Island population was almost driven to extinction by extreme habitat modification and collecting in the late 19th century. Analysis of a long-term (1957–2001) dataset, following the population's recovery, reveals a significant decline in tuatara body condition over time, which is more pronounced in females. Declining body condition, coupled with very low reproductive output, may be symptomatic of a density-dependent response to elevated population size exacerbated by resource limitation. Sex-specific effects that disadvantage females could compromise this small population, particularly as it exhibits a male-biased sex ratio. We recommend removal of infrequently used structures and habitat restoration to alleviate intense resource competition. Population-level manipulation should be considered if future monitoring indicates an increasingly male-biased sex ratio and continued decline of female body condition. [ABSTRACT FROM AUTHOR]

Conservation reintroductions play a vital role in the recovery of threatened species, and clear goals and objectives are essential for evaluating their effectiveness. In this study, we assessed short‐term success (<18 months) of trial reintroductions of the Extinct in the Wild blue‐tailed skink (Cryptoblepharus egeriae) and Lister's gecko (Lepidodactylus listeri) on Christmas Island. Our evaluation criteria focused on body condition, reproduction, habitat suitability, survival and population growth. In 2018 and 2019, 170 C. egeriae and 160 L. listeri were translocated from a local captive breeding facility to a 2600 m2 outdoor fenced enclosure designed to exclude a predatory snake. Despite body condition declining immediately following release for both species, it had improved by 6 months post‐release. We also detected successful reproduction in both species. Apparent survival was high for C. egeriae but low for L. listeri, and population growth was only evident in C. egeriae. We were unable to determine whether low survival of L. listeri in the release site was due to high post‐release dispersal (beyond the exclosure) or mortality. Both species selected habitats that contained high rock and log cover and avoided areas with low ground cover. Appropriate assessment criteria, as utilized in this study, enable objective and timely evaluations of reintroduction success, thereby facilitating the improvement and refinement of reintroduction protocols. Our study showed that C. egeriae can establish (in the short‐ to medium‐term) in a site from which a principal threat has been excluded and undergo rapid population growth, whereas under current conditions L. listeri cannot. However, we also demonstrate that such medium‐term success may not lead to long‐term success, as the rapid increase in C. egeriae population was reversed between 29 and 31 months after release because the barrier used to exclude an invasive predator, the wolf snake (Lycodon capucinus), was breached. [ABSTRACT FROM AUTHOR]