Poor Display Repertoire, Tolerance and Kleptobiosis: Results of Specialization in an Ant-Eating Spider (Araneae, Zodariidae)

The agonistic display repertoire of myrmecophagous Zodarion rubidum has five displays. This is fewer than in other spiders, which is a result of the short time spent in contests (4 s). Such a short duration seems to be an adaptation to living among foraging ants, which are dangerous to spiders. The interaction procedure was markedly affected by the presence of preyimmobilized ant. Contests between individuals without prey, or each holding prey, were usually resolved by leg waving. But contests between an individual without and an individual with prey escalated to more aggressive levels. Nevertheless, spiders were never observed to harm or cannibalize one another. Absence of cannibalism is explained as a result of diet specialization: only ants elicit a predatory behavior and provide Zodarion spiders with optimal nutrients. Some spiders used kleptobiosis to gain ants. They first tried to gain immobilized prey aggressively and if failed they adopted a stealthy tactic and shared the prey with the owner. Kleptobiosis is an alternative foraging strategy for Zodarion spiders as it reduces risks associated with hunting dangerous ants.