Invasive species threaten biodiversity globally, and invasive mammalian predators are particularly damaging, having contributed to considerable species decline and extinction. We provide a global metaanalysis of these impacts and reveal their full extent. Invasive predators are implicated in 87 bird, 45 mammal, and 10 reptile species extinctions-58% of these groups' contemporary extinctions worldwide. These figures are likely underestimated because 23 critically endangered species that we assessed are classed as "possibly extinct." Invasive mammalian predators endanger a further 596 species at risk of extinction, with cats, rodents, dogs, and pigs threatening the most species overall. Species most at risk from predators have high evolutionary distinctiveness and inhabit insular environments. Invasive mammalian predators are therefore important drivers of irreversible loss of phylogenetic diversity worldwide. That most impacted species are insular indicates that management of invasive predators on islands should be a global conservation priority. Understanding and mitigating the impact of invasive mammalian predators is essential for reducing the rate of global biodiversity loss.I nvasive mammalian predators ("invasive predators" hereafter) are arguably the most damaging group of alien animal species for global biodiversity (1-3). Species such as cats (Felis catus), rats (Rattus rattus), mongoose (Herpestes auropunctatus), and stoats (Mustela erminea) threaten biodiversity through predation (4, 5), competition (6), disease transmission (7), and facilitation with other invasive species (8). The decline and extinction of native species due to invasive predators can have impacts that cascade throughout entire ecosystems (9). For example, predation by feral cats and red foxes (Vulpes vulpes) has led to the decline or extinction of two thirds of Australia's digging mammal species over the past 200 y (10, 11). Reduced disturbance to topsoil in the absence of digging mammals has led to impoverished landscapes where little organic matter accumulates and rates of seed germination are low (10). In the Aleutian archipelago, predation of seabirds by introduced Arctic foxes (Alopex lagopus) has lowered nutrient input and soil fertility, ultimately causing vegetation to transform from grasslands to dwarf shrub/forb-dominated systems (12).Mitigating the negative impacts of invasive mammalian predators is a primary goal of conservation agencies worldwide (1,13,14). Regardless, there remains no global synthesis of the role of invasive predators in species declines and extinctions (but see refs. 3 and 15). Here, we quantify the number of bird, mammal, and reptile species threatened by, or thought to have become extinct (since AD 1500) due to, invasive mammalian predators. We use metaanalysis to examine taxonomic and geographic trends in these impacts and show how the severity of predator impacts varies according to species endemicity and evolutionary distinctiveness.
Results and DiscussionIn total, 596 threatened and 142 extinc...
