Confusion effect in a reptilian and a primate predator

The confusion effect is claimed to be one benefit of group living with resp ect to predator avoidance: it is more difficult for predators to capture pr ey that is surrounded by other conspecifics than to capture an isolated ind ividual. So far, the predictions of the confusion effect have been tested m ainly in aquatic predators. As the confusion effect is seen to be a general problem for predators, terrestrial predators of two different vertebrate c lasses were used to test it. The prey (mealworms and black beetles, Tenebri o molitor) was harmless and had no chance of predator avoidance. Thus, conf ounding effects of group defence and enhanced vigilance were controlled. Bo th leopard geckos (Eublepharis macularius) and common marmosets (Callithrix jacchus) took longer to catch one out of several prey compared to one sing le prey. Leopard geckos showed more fixations (changing of head position) w hen confronted with 20 mealworms than when confronted with only one mealwor m, thus showing indications of being 'confused'.