Abstract
Competitive displacement is a form of interspecific competition. Here, we explore the potential for competitive displacement in refuges of the endangered katipō spider (Latrodectus katipo) by the invasive false katipō (Steatoda capensis) (Araneae, Theridiidae). We conducted experimental assays using artificial refuges to test individual preferences for refuge shape, surface, and height. We also tested how refuge type affects the number of web trap lines used for prey capture. Both species preferred triangular refuges over rectangular refuges, with no evidence of a preference for other refuge types. For reasons which remain unclear, individuals varied in their preferences for surface and height. Katipō spiders showed site fidelity in all three assays, while false katipō spiders only showed site fidelity in the shape and surface assays. However, there was also evidence of individual variation in site fidelity in the shape assay. Spiders constructed more web trap lines beneath the triangular refuges, potentially due to their preference for triangular refuges. We suggest that overlapping refuge preferences, but not web structure, may contribute to competition and the potential for competitive displacement of the katipō by false katipō. Although not exclusively preferred by katipō, introducing artificial triangular refuges in katipō habitats should be tested as a means of supporting the persistence and expansion of katipō populations.