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On Aotea/Great Barrier Island, New Zealand, two invasive rat species (Pacific rats and ship rats) pose risks to the ecosystems and challenge the management in two sanctuaries. At Glenfern Sanctuary (83 ha) an eradication has successfully removed ship rats and a predator-proof fence prevents reinvasion. However, Pacific rats persist in low abundance. At Windy Hill Sanctuary (770 ha) intensive rodent control maintains both species at low abundance despite ongoing reinvasion. A capture-mark-recapture study was conducted between February and April in 2016 and repeated between July and September 2017 to determine population densities, confirm species composition, and analyse the effects of time, population density, and interspecific competition on rat behaviour. Live traps were monitored with camera traps to analyse behaviour of rats around traps. Population density and detection probability of Pacific rats varied between times reflecting seasonality in food abundance and rat reproduction. The detection probability of Pacific rats also differed between sites, being higher at Glenfern Sanctuary than at Windy Hill Sanctuary, presumably due to interspecific competition with ship rats. Where Pacific rats were the sole species they were captured in traps in the first night. However, in coexistence with ship rats, Pacific rat detection was delayed by at least ten days. Population density influenced the number of trap encounters and interactions but did not significantly influence the capture rate. Interspecific competition was identified as problematic for monitoring, controlling, and eradicating Pacific rats.

The approximately 320 atolls of the world, scattered across the tropical oceanic basins, constitute a unique type of ecosystem in that they are each an integrated unit consisting of island, coral reef, and lagoon components. Atolls have a complex geology, ecology, and biogeography, which can be fully appreciated only by transcending the classic boundary thinking of marine and terrestrial realms. The atolls we observe today were shaped by Quaternary sea-level fluctuations, which imposed strong environmental filters on their communities. As entirely biogenic, reef-borne structures, the islands of atolls depend upon marine productivity, which catalyzes island community assembly. Island species communities exist in complex dynamic equilibria with the surrounding oceanographic conditions. Energy fluxes and element cycles of the atoll system readily cross habitat boundaries and create a productive, diverse, and biomass-rich ecosystem on land and underwater. Past human disturbances and future global change put atolls at the forefront of conservation and ecological restoration. [ABSTRACT FROM AUTHOR]

Residential green spaces in cities can make a significant contribution to urban conservation. To engage urban residents in conservation, we need to understand what influences participation. We interviewed leaders of community conservation groups and surveyed members of the public in Auckland, New Zealand using an anonymous questionnaire. We investigated whether environmental attitudes differ between those who do and do not participate in conservation actions (volunteering in a community conservation group and/or controlling pest mammals), and the motivations and barriers to participating in conservation actions. We found that conservation leaders often founded their conservation groups with a biodiversity motivation, whereas many of their group members subsequently joined and continued to participate for social reasons. Conservation group members were more likely to be in favor of pest control and had more positive environmental attitudes than non-participants. They found group work more motivating and productive than working alone. For people already participating in conservation (controlling pests, leading a group, or volunteering), the most common barrier to increasing participation was opportunity, most notably a lack of time. We found that people tended to control pest mammals for self-interested reasons, such as preventing damage to their homes (67%; n = 358), whilst biodiversity motivations (protecting native species) were secondary (53%; n = 283). For people not participating in pest control, the primary barrier was a lack of interest in participating (26%; n = 109). Although people were supportive of conservation, biodiversity motivations alone are unlikely to be a sufficient motivator for participation. Given the range of different motivations and barriers, targeted messaging (e.g., promoting social connections) could increase participation in urban conservation. [ABSTRACT FROM AUTHOR]

More than US$21 billion is spent annually on biodiversity conservation. Despite their importance for preventing or slowing extinctions and preserving biodiversity, conservation interventions are rarely assessed systematically for their global impact. Islands house a disproportionately higher amount of biodiversity compared with mainlands, much of which is highly threatened with extinction. Indeed, island species make up nearly two-thirds of recent extinctions. Islands therefore are critical targets of conservation. We used an extensive literature and database review paired with expert interviews to estimate the global benefits of an increasingly used conservation action to stem biodiversity loss: eradication of invasive mammals on islands. We found 236 native terrestrial insular faunal species (596 populations) that benefitted through positive demographic and/or distributional responses from 251 eradications of invasive mammals on 181 islands. Seven native species (eight populations) were negatively impacted by invasive mammal eradication. Four threatened species had their International Union for the Conservation of Nature (IUCN) Red List extinction-risk categories reduced as a direct result of invasive mammal eradication, and no species moved to a higher extinction-risk category. We predict that 107 highly threatened birds, mammals, and reptiles on the IUCN Red List-6% of all these highly threatened species-likely have benefitted from invasive mammal eradications on islands. Because monitoring of eradication outcomes is sporadic and limited, the impacts of global eradications are likely greater than we report here. Our results highlight the importance of invasive mammal eradication on islands for protecting the world's most imperiled fauna.

Central to the growing field of island ecological restoration is the removal of invasive rodents. The lack of information on rodent tropical ecology is a limiting factor for the success of such eradication attempts on tropical islands worldwide. In Mexico, 14 successful rodent eradications have occurred, 6 of them on dry and wet tropical islands, and the others on temperate islands. All recent projects included research components in order to inform management strategies. Here we summarize the main research findings and management recommendations, using the case of Isabel Island to illustrate how efficacy and efficiency of conservation initiatives can be improved when informed by directed research.

When new individuals from a pest species are detected following eradication, identifying whether the new individuals are survivors from the eradication attempt, or reinvaders from another population, is important for management practices. Pearl Island (512 ha) in New Zealand was the first island in the world on which simultaneous eradication of all three invasive rat species was attempted. Rats were detected again 9 months after the eradication operation. We use genetic assignment methods to discriminate between survivor and reinvader hypotheses. All rats found on Pearl Island after eradication were likely to be reinvaders from an adjacent population on much larger Stewart Island (174,600 ha), suggesting that rats were swimming to the island at a rate much greater than anticipated, but that the original eradication was successful. Adequate genetic signal was obtained from opportunistically collected samples, making the method feasible for conservation managers with limited time and resources.