Abstract
Biological invasions threaten native species and ecosystems worldwide. Estimating the level of risk that an invasive alien species poses to native species across landscapes is important for prioritizing mitigation efforts. We describe a risk assessment approach that incorporates spatial heterogeneity in effects and illustrate this method by considering the risk that the red imported fire ant (Solenopsis invicta) presents to two native birds. The common ground-dove (Columbina passerina), an oviparous, ground-nesting species with altricial young that prefers open habitats, is more susceptible to impacts from fire ants than the swallow-tailed kite (Elanoides forficatus), which occupies closed-canopy forests, nests high in trees, is oviparous and has altricial young. Risk approaches that consider land scapes and that are spatially explicit are of particular relevance as remaining un-developed lands become increasingly un common, disjointed and more important for the management and recovery of native species and ecosystems.