Invasive species are a major driver of native species declines, frequently resulting in a reduction of ecosystem function. Though control of invasive species is often beneficial, it can create other ecological issues. However, studying the results can give insight into the benefits of removal and most effective management techniques. A model invasive species to test the effects of removal is the red‐imported fire ant (Solenopsis invicta, hereafter RIFA), which depredates and competes with native species. We hypothesized that following removal, RIFA would recolonize treated areas from untreated borders, resulting in reinvasion and higher densities due to elimination of competition from native species that would also be extirpated by treatments. To test our hypothesis, we compared RIFA relative abundance on large sites (>400 ha) treated with a granular insecticide (Extinguish Plus, Central Life Sciences, Schaumburg, IL) in southwest Georgia, USA. Extinguish Plus effectively removed RIFA, but the treated sites were reinvaded approximately 14 months after treatment with higher densities of RIFA than on untreated areas, potentially reflecting release from competition from native ants removed by treatments. Invasive species removal may elicit a rapid recolonization via a density‐dependent response mechanism and potentially increase abundance of the target species. Management strategies integrating temporal and spatial replication of control measures and multiple management techniques will be most successful in controlling invasive species.

Efforts to remove invasive species may benefit native species, but the effects can be complex and unpredictable. Thus, studies of invasive-species removal provide important information for guiding management and providing insight about variation in post-removal impacts within the community. Using southern pine-grassland ecosystems as a model system, we hypothesized that removal of the long-established red-imported fire ant (Solenopsis invicta, hereafter RIFA) would positively influence altricial Peromyscus species, due to increased survival of young in the nest and thus increased recruitment to the population, but would not impact semi-precocial hispid cotton rats (Sigmodon hispidus), which are mobile more quickly after birth and thus at less risk of depredation by RIFA. We compared small mammal populations on sites treated with a granular insecticide (Extinguish Plus) to remove RIFA in southwestern Georgia, United States, from April 2018 to December 2019. As expected, we detected no difference in cotton rat recruitment. However, contrary to our prediction, the same was true for cotton mice (Peromyscus gossypinus) and oldfield mice (Peromyscus polionotus). We found RIFA removal increased survival both of cotton rats and cotton mice, increasing average population rate of change (λ) on treated sites during the study period. In contrast, we observed lower survival of oldfield mice, with similar λ estimates on treated and untreated sites, but low sample sizes were problematic for this species. Our results show that removal of invasive species can have positive impacts for native species, but both the magnitude of RIFA effects on small mammals and mechanisms by which impacts occur are complex.