UC Santa Cruz

Seabirds are the most threatened group of marine animals, with 29% of species at some risk of extinction. Significant threats to seabirds occur on islands where they breed, but in many cases, effective island conservation can mitigate these threats. To guide island-based seabird conservation actions, we identified all islands with extant or extirpated populations of the 98 globally threatened seabird species recognized by the IUCN Red List and quantified the presence and extent of threatening invasive alien species, protected areas and human populations. We used these data to highlight feasible island conservation opportunities. We identified 1,362 threatened seabird breeding populations on 968 islands. Threatening invasive species and/or lack of adequate protection was identified on 803 of these islands (580 (59.9%) and 609 (63%) islands, respectively). Most identified islands were small (57% were <1km2), uninhabited (74%), and occurred in countries designated as high or middle income (96%). Collectively, these attributes make threatened seabird islands ideal for successful island conservation action. As a result, globally threatened seabirds are in a rare situation whereby some of the most intense threats are feasible to mitigate, providing a significant opportunity for important and effective seabird conservation.