Meeting Abstract

P3.25  Wednesday, Jan. 6  Effects of predator diversity and density on prey behavior: inter-population differences of side-blotched lizards (Uta stansburiana) exposed to snakes, lizards and birds TILLMAN, Jennifer L.*; ZANI, Peter A.; Lafayette College; Gonzaga University zani@gonzaga.edu

Animals in high-predation environments tend to react more quickly and effectively in the presence of predators when compared to populations experiencing low predation pressure. Yet, habitat differences among populations confound many previous studies. We studied a common prey species, side-blotched lizards (Uta stansburiana), in Oregon and Nevada to test for behavioral differences among populations that varied in types and numbers of predators, but that occupied similar habitat. We measured several traits associated with predator exposure: time spent moving and displaying, distance moved, and perch height. We also quantified potential predators (snakes, lizards, birds) at each site. Four study populations varied in predator diversity from eight potential predators (three snakes, three lizards, two birds) to as few as one (a snake). Predator density among populations ranged from as many as 20 per ha to as few as one. The two populations exposed to the highest predation potential spent less time displaying, moved less often, and moved shorter distances. Comparison among populations suggests that predator density is as important as predator diversity. A high-predation population exposed to a high density of one major predator (leopard lizards, Gambelia wislizenii), but lacking collared (Crotaphytus bicinctores) and whiptail (Aspidoscelis tigris) lizards, exhibited more visibility-reducing behavior (fewer movements and displays) than a high-predation population exposed to similar predator density, but consisting of all three predator species. We suggest that the higher lizard diversity gives potential predators more prey to choose from and reduces the risk to common prey species, such as Uta.