Giving predators a wide berth: quantifying behavioral predator shadows in colonizing aquatic beetles.

The perceived quality of habitat patches in complex landscapes is highly context dependent. Characteristics of neighboring patches in such complex landscapes can influence perceived habitat quality, altering colonization dynamics and community structure. Spatial contagion of predation risk across patches has been observed over smaller spatial scales in aquatic systems. Naturally colonizing aquatic beetles were used to examine the spatial dynamics of risk contagion by quantifying the size of predator shadows around fish patches across spatial scales potentially involving numerous patches in natural landscapes. These consisted of fish free, replicate experimental mesocosm arrays radiating from larger central mesocosms containing fish, and allowed examination of the effect of distance to fish on beetle abundance, rarified species richness, and variation in species responses. Overall, beetles avoided pools closer to fish, but species varied in colonization pattern, resulting in species-specific predator shadows and potential behavioral species sorting. The spatial and phylogenetic extent of contagion and other context-dependent effects has implications for the role of complex behavior in the dynamics of communities and metacommunities.