CONICET | Buscador de Institutos y Recursos Humanos

Abstract: The introduction of exotic plant species may generate habitat modifications that in turn increase the predation risk for preys, either by making them more conspicuous, by offering perches to predators or by limiting suitable refuges. We compared predation pressure and escape behavior of two sympatric lizard species (Liolaemus wiegmannii and L. multimaculatus) inhabiting forested and nonforested grasslands of the pampasic coastal sand dunes of Buenos Aires province, Argentina. Predation pressure was estimated by measuring the abundance of avian predators and calculating the predation rate on lizard plasticine replicas. Escape behavior was studied by searching for lizards in the field. Once a lizard was sighted we recorded flight initiation distance (FID) between the observer and the lizard before it started escaping and the type of microhabitat used as refuge. Both lizard species prefer refuges in native plants, but when they are scarce Acacia longifolia was the alternative refuge. In forested habitats sand-burying behavior is a complementary strategy used by L. multimaculatus. FID of L. wiegmannii was greater in forested habitats than in nonforested ones, confirming the assumptions of theoretical models of escape behavior. By contrast, L. multimaculatus showed a short FID in forested habitats, mostly because sand-burying behavior allows this species to hide ??beneath their feet?? reducing risks typically associated with exposed areas. Plasticity in antipredatory behavior suggests that these lizards could learn to recognize predators and develop a suitable antipredatory behavior. We conclude that increased predation pressure and structural alterations of the habitat generated by exotic trees of A. longifolia affect the decisions that determine how, when and where these lizards flee.