Differential habitat use and recruitment facilitate coexistence in a community with intraguild predation

Theory predicts that species engaged in intraguild predation (IGP) can only coexist under limited conditions, yet IGP is common in nature. Habitat complexity can promote co-existence by reducing encounter rates, but little is known about the contribution of differential habitat use. We hypothesized that differential use of alternative habitats promotes coexistence of an IG predator and prey. We evaluated predictions of this hypothesis with an experimental introduction of an IG predator fish into four natural stream communities that previously contained only the IG prey fish. We monitored the development of this IGP over the course of four years to determine how each species used alternative stream habitats. The introduced species prefers pool habitats while the resident species was more evenly distributed across pools and riffles. The density of the resident decreased in the pool habitat preferred by the invader, accompanied by a local increase in the mean of the resident size distribut...