Abundance Redistribution Increases Predator-Prey Interaction Potentials Among North American Birds

Species are shifting their geographical ranges, yet the consequences of these spatial redistributions for species interactions have not been examined at broad spatial and temporal scales. Here, we characterize shifts in the potential for predator-prey interactions among North American birds over the past 50 years. We first predict potential predator-prey interactions based on existing data, then construct a novel, abundance-weighted metric of interaction potential for each pair of predator and prey species in local communities. We found nearly universal increases in predator-prey interaction potentials across North America that are mostly driven by increases in predator abundances. The spatial redistributions of predators and prey lead to turnover of interactions within local communities that are less associated with changes in climate than with human-induced land use changes. Our results highlight the importance of considering traits, abundances, and species interactions-including known and potential interactions-when studying the ecological consequences of range shifts.