Responses of naive lizards to predator chemical cues

The ability to recognize chemical cues from predatory snakes is congenital in the common lizard Lacerta vivipara. This conclusion follows from a series of experiments in which we observed the behavior of naive lab-born lizards in terraria that had previously been inhabited by predatory snakes. Chemicals from both the viper Vipera berus (a sympatric predator) and the smooth snake Coronella austriaca (an allopatric saurophagic snake) elicited a sharp increase in tongue-flick rates. The lizards, when confronted with snake chemicals, exhibited an increased number of foot shakes, tail vibrations and starts, and moved about in a strange, jerky way. In these aspects, the behavioral response of juvenile lizards resembled that of adults. The only quantitative age-related difference concerned thermoregularoty behavior: whereas juveniles refrained almost completely from basking in the presence of snake chemicals, adult lizards basked equally long in snake and control experiments.