Do lizards (Podarcis siculus) react to whip snake (Hierophis viridiflavus) scents? A comparative test on odour stimuli recognition

Abstract

Abstract We tested the ability in the ruin lizard (Podarcis siculus) to discriminate between odour of a predator (the whip snake Hierophis viridiflavus) and those from harmless sources. We analysed two lizard populations: one (PP) predated by snakes and another (PNP) where no snakes occur. We tested the rate of tongue flick directed to cotton-tips impregnated with odours, and the rate of tongue flick, the time spent in immobility, escaping and exploring the terrarium containing a diffuse odour. We used the smell of the snake as dangerous stimulus, water as blank control, and cologne as complex control. Both populations did not discriminate snake cue from complex odour in both the experiments. PP individuals were more active and prone to analysing and exploring the stimuli and the environment than PNP lizards. In PP, the higher interest towards cologne and snake scents could be triggered just by their complexity that requires more tongue flicks to be ‘analysed’, with no apparent adaptive anti-predatory value. Overall, we observed a total responsiveness and activity pattern higher in the PP respect to PNP.