Forest owl community response following the removal of an intraguild invader

Invasive predators can reshape native predator assemblages, triggering cascading changes in broader wildlife communities. In western North America, the barred owl (Strix varia) is an invasive apex predator with well-documented negative impacts on congeneric northern spotted owls (Strix occidentalis caurina), but impacts on other native forest owls are poorly understood. We coupled a large-scale removal experiment with a passive acoustic monitoring network to quantify species-specific and community-level responses of a five-species assemblage of native forest owls to the lethal removal of invasive barred owls. Our results supported predictions of intraguild predation theory, where smaller bodied, nocturnal species most susceptible to predation and resource competition from larger barred owls benefitted from removal, whereas a diurnally active owl species and a larger bodied species showed little to no response. We conclude that focused management actions limiting the occurrence of barred owls can provide spatial refugia for spotted owls and other sympatric native owl species, thereby promoting forest biodiversity.