Globally important islands where eradicating invasive mammals will benefit highly threatened vertebrates

Abstract

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 Earth’s 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 world’s nations.

7,000 years of turnover: historical contingency and human niche construction shape the Caribbean’s Anthropocene biota

“…Invasive species represent one of the greatest management challenges facing insular biota globally [57, 58]. Our synthesis builds on a body of literature showing that the presence of non-native species in the context of altered landscapes and growing human populations is not a new phenomenon; rather, the predisposition of certain insular ecosystems to the effects of modern invasive species may be undergirded by their unique accumulated histories of Indigenous and colonial activity, demanding inclusion of paleontological and archaeological knowledge in conservation planning [56].…”

“…If the goal is to maintain the status quo of insular biodiversity and protect still-surviving endemic species, eradication of non-native species represents the most significant gain for island endemics [57]. A global analysis of insular systems indicated that the Caribbean has a large proportion of biologically important islands (45 of 292, or 15.4%) where eradication would be beneficial [58]. Ongoing eradications of Rattus from small islands used heavily by seabirds may have positive ecological effects on nutrient cycling [59].…”

A review of mammal eradications on Mediterranean islands

“…An important future output is a priority list, ranking Mediterranean islands in terms of cost‐effectiveness of invasive mammal eradication and comparing benefits to the monetary costs, as has already been done for other contexts on a different scale (e.g. Brooke et al , Capizzi et al , Holmes et al ). Prioritising conservation actions can be a strategic tool and a useful guide for managers, conservationists, and politicians, allowing them to convey limited resources to the worthiest restoration projects (Wilson et al , Helmstedt et al ).…”

Stuck amongst introduced species: Trophic ecology reveals complex relationships between the critically endangered Niau kingfisher and introduced predators, competitors and prey

“…Considering the critical size of the sole existing population of Niau kingfishers, it is important to avoid any additional mortality due to key prey rarefaction (or even direct preda-tion). For these reasons, Niau Island was recently listed amongst islands worldwide where introduced mammal eradications are required to prevent imminent extinction of endemic vertebrates (Holmes et al 2019).…”