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Invasive alien mammals are the major driver of biodiversity loss and ecosystem degradation on islands. Over the past three decades, invasive mammal eradication from islands has become one of society's most powerful tools for preventing extinction of insular endemics and restoring insular ecosystems. As practitioners tackle larger islands for restoration, three factors will heavily influence success and outcomes: the degree of local support, the ability to mitigate for non-target impacts, and the ability to eradicate non-native species more cost-effectively. Investments in removing invasive species, however, must be weighed against the risk of reintroduction. One way to reduce reintroduction risks is to eradicate the target invasive species from an entire archipelago, and thus eliminate readily available sources. We illustrate the costs and benefits of this approach with the efforts to remove invasive goats from the Galápagos Islands. Project Isabela, the world's largest island restoration effort to date, removed >140,000 goats from >500,000 ha for a cost of US$10.5 million. Leveraging the capacity built during Project Isabela, and given that goat reintroductions have been common over the past decade, we implemented an archipelago-wide goat eradication strategy. Feral goats remain on three islands in the archipelago, and removal efforts are underway. Efforts on the Galápagos Islands demonstrate that for some species, island size is no longer the limiting factor with respect to eradication. Rather, bureaucratic processes, financing, political will, and stakeholder approval appear to be the new challenges. Eradication efforts have delivered a suite of biodiversity benefits that are in the process of revealing themselves. The costs of rectifying intentional reintroductions are high in terms of financial and human resources. Reducing the archipelago-wide goat density to low levels is a technical approach to reducing reintroduction risk in the short-term, and is being complemented with a longer-term social approach focused on education and governance. [ABSTRACT FROM AUTHOR]

Rails (family Rallidae) are vulnerable to the impacts of invasive mammals, and this is particularly true for species on oceanic islands. The endemic Galápagos rail (Laterallus spilonotus) is no exception; previous studies suggested that Galápagos rail populations were heavily impacted due to predation by pigs (Sus scrofa) and habitat degradation by goats (Capra hircus). Following recent conservation actions that have eradicated pigs and goats from Santiago Island, changes in rail abundance were observed. Estimated densities have increased by over an order of magnitude between 1986/1987 and 2004/2005. Limited data on rail densities from two additional islands over the same time period provide further support to the notion that the eradications spurred recovery. On Fernandina Island, where there is no history of invasive mammals, rail density increased slightly between 1986/1987 and 2004/2005. In contrast, on Isabela Island where invasive mammals were present both in 1986/1987 and 2004/2005, rail densities declined at one site between those two time periods. While the Galápagos rail is vulnerable to invasive mammals, the observed changes following goat and pig removal are encouraging for Rallidae conservation. [Copyright &y& Elsevier]