A great part of the Earth's biodiversity occurs on islands, to which humans have brought a legion of invasive species that have caused population declines and even extinctions. The domestic cat is one of the most damaging species introduced to islands, being a primary extinction driver for at least 33 insular endemic vertebrates. Here, we examine the role of feral cats in the context of the island biodiversity crisis, by combining data from reviews of trophic studies, species conservation status reports, and eradication campaigns. The integration of these reviews permits us to identify priority islands where feral cat eradications are likely to be feasible and where cats are predicted to cause the next vertebrate extinctions. Funding agencies and global conservation organizations can use these results to prioritize scarce conservation funds, and national and regional natural resource management agencies can rank their islands in need of feral cat eradication within a global context. © 2013 by American Institute of Biological Sciences. All rights reserved.

Due to its unique biodiversity and extreme endemism rates, New Caledonia archipelago is listed as one of Earth’s 35 biodiversity hotspots. New Caledonian biota is now threatened by invasive species, with introduced rats considered to be particularly damaging. At the initiative of local institutions and NGOs, an innovative scientific experiment has been launched to quantify the Response of Forest Ecosystems to Rodent and Cat Control (REFCOR) and to test the relevance of such control at a large spatial scale (200 ha) on a dense evergreen rainforest (Mont Panié Wilderness Nature Reserve). Rat control will begin mid-2014 with a short toxin knockdown, and will thereafter involve intensive trapping sessions over the next 6 years, together with biodiversity monitoring and experiments. Rat impact studies initiated in early 2013 also aim to identify possible biodiversity indicators that could be used for a rapid assessment of rat control efficiency and effects. One of the major impacts of invasive rats is the disruption caused to plant and bird reproduction processes, placing them at high risk. Pre-and post-control experiments include the assessment of palm fruit consumption rates and of predation risk to artificial bird nests. Initial surveys of both rat populations and palm fruits (2 species), as well as artificial bird nest predation experiments, were conducted in 2013. Rat abundance was high, fluctuating among study areas and seasons, with more individual reproducers in December than in May. Fruit predation was high for one of the two species, in line with the rat abundance pattern. Surprisingly, artificial bird nest predation by rats was far lower than expected. These first results corroborate the influence of rats on some taxa. Monitoring and experiments will be repeated after and throughout rat control. This “before-after-control-impact” project, conducted in close collaboration with local stakeholders (Dayu Biik NGO), offers a unique opportunity to evaluate 1) the feasibility of controlling rat populations in the New Caledonian rainforest by trapping as an alternative to long-term poisoning, and 2) the benefits of rat control for native biodiversity and rainforest ecosystem functioning.

Invasive alien species are a major threat to native insular species. Eradicating invasive mammals from islands is a feasible and proven approach to prevent biodiversity loss. We developed a conceptual framework to identify globally important islands for invasive mammal eradications to prevent imminent extinctions of highly threatened species using biogeographic and technical factors, plus a novel approach to consider socio-political feasibility. We applied this framework using a comprehensive dataset describing the distribution of 1,184 highly threatened native vertebrate species (i.e. those listed as Critically Endangered or Endangered on the IUCN Red List) and 184 non-native mammals on 1,279 islands worldwide. Based on extinction risk, irreplaceability, severity of impact from invasive species, and technical feasibility of eradication, we identified and ranked 292 of the most important islands where eradicating invasive mammals would benefit highly threatened vertebrates. When socio-political feasibility was considered, we identified 169 of these islands where eradication planning or operation could be initiated by 2020 or 2030 and would improve the survival prospects of 9.4% of the Earths most highly threatened terrestrial insular vertebrates (111 of 1,184 species). Of these, 107 islands were in 34 countries and territories and could have eradication projects initiated by 2020. Concentrating efforts to eradicate invasive mammals on these 107 islands would benefit 151 populations of 80 highly threatened vertebrates and make a major contribution towards achieving global conservation targets adopted by the worlds nations.

Plastic pollution is distributed patchily around the worlds oceans. Likewise, marine organisms that are vulnerable to plastic ingestion or entanglement have uneven distributions. Understanding where wildlife encounters plastic is crucial for targeting research and mitigation. Oceanic seabirds, particularly petrels, frequently ingest plastic, are highly threatened, and cover vast distances during foraging and migration. However, the spatial overlap between petrels and plastics is poorly understood. Here we combine marine plastic density estimates with individual movement data for 7137 birds of 77 petrel species to estimate relative exposure risk. We identify high exposure risk areas in the Mediterranean and Black seas, and the northeast Pacific, northwest Pacific, South Atlantic and southwest Indian oceans. Plastic exposure risk varies greatly among species and populations, and between breeding and non-breeding seasons. Exposure risk is disproportionately high for Threatened species. Outside the Mediterranean and Black seas, exposure risk is highest in the high seas and Exclusive Economic Zones (EEZs) of the USA, Japan, and the UK. Birds generally had higher plastic exposure risk outside the EEZ of the country where they breed. We identify conservation and research priorities, and highlight that international collaboration is key to addressing the impacts of marine plastic on wide-ranging species.